Beth L. Pruitt

All Publications

• Multifunctional Integrated Sensors for Multiparameter Monitoring Applications JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Roozeboom, C. L., Hill, B. E., Vu Anh Hong, V. A., Ahn, C. H., Ng, E. J., Yang, Y., Kenny, T. W., Hopcroft, M. A., Pruitt, B. L. 2015; 24 (4): 810-821

  View details for DOI 10.1109/JMEMS.2014.2349894

  View details for Web of Science ID 000358952600007

• Self-sensing cantilevers with integrated conductive coaxial tips for high-resolution electrical scanning probe metrology JOURNAL OF APPLIED PHYSICS Haemmerli, A. J., Harjee, N., Koenig, M., Garcia, A. G., Goldhaber-Gordon, D., Pruitt, B. L. 2015; 118 (3)

  View details for DOI 10.1063/1.4923231

  View details for Web of Science ID 000358429200024

• Spatial distribution of cell-cell and cell-ECM adhesions regulates force balance while maintaining E-cadherin molecular tension in cell pairs MOLECULAR BIOLOGY OF THE CELL Sim, J. Y., Moeller, J., Hart, K. C., Ramallo, D., Vogel, V., Dunn, A. R., Nelson, W. J., Pruitt, B. L. 2015; 26 (13): 2456-2465

  Abstract

  Mechanical linkage between cell-cell and cell-extracellular matrix (ECM) adhesions regulates cell shape changes during embryonic development and tissue homoeostasis. We examined how the force balance between cell-cell and cell-ECM adhesions changes with cell spread area and aspect ratio in pairs of MDCK cells. We used ECM micropatterning to drive different cytoskeleton strain energy states and cell-generated traction forces and used a Förster resonance energy transfer tension biosensor to ask whether changes in forces across cell-cell junctions correlated with E-cadherin molecular tension. We found that continuous peripheral ECM adhesions resulted in increased cell-cell and cell-ECM forces with increasing spread area. In contrast, confining ECM adhesions to the distal ends of cell-cell pairs resulted in shorter junction lengths and constant cell-cell forces. Of interest, each cell within a cell pair generated higher strain energies than isolated single cells of the same spread area. Surprisingly, E-cadherin molecular tension remained constant regardless of changes in cell-cell forces and was evenly distributed along cell-cell junctions independent of cell spread area and total traction forces. Taken together, our results showed that cell pairs maintained constant E-cadherin molecular tension and regulated total forces relative to cell spread area and shape but independently of total focal adhesion area.

  View details for DOI 10.1091/mbc.E14-12-1618

  View details for Web of Science ID 000357053400006

• Mechanical strain induces E-cadherin-dependent Yap1 and beta-catenin activation to drive cell cycle entry SCIENCE Benham-Pyle, B. W., Pruitt, B. L., Nelson, W. J. 2015; 348 (6238): 1024-1027

  View details for DOI 10.1126/science.aaa4559

  View details for Web of Science ID 000355276600046

• Cell adhesion. Mechanical strain induces E-cadherin-dependent Yap1 and ß-catenin activation to drive cell cycle entry. Science Benham-Pyle, B. W., Pruitt, B. L., Nelson, W. J. 2015; 348 (6238): 1024-1027

  Abstract

  Mechanical strain regulates the development, organization, and function of multicellular tissues, but mechanisms linking mechanical strain and cell-cell junction proteins to cellular responses are poorly understood. Here, we showed that mechanical strain applied to quiescent epithelial cells induced rapid cell cycle reentry, mediated by independent nuclear accumulation and transcriptional activity of first Yap1 and then β-catenin. Inhibition of Yap1- and β-catenin-mediated transcription blocked cell cycle reentry and progression through G1 into S phase, respectively. Maintenance of quiescence, Yap1 nuclear exclusion, and β-catenin transcriptional responses to mechanical strain required E-cadherin extracellular engagement. Thus, activation of Yap1 and β-catenin may represent a master regulator of mechanical strain-induced cell proliferation, and cadherins provide signaling centers required for cellular responses to externally applied force.

  View details for DOI 10.1126/science.aaa4559

  View details for PubMedID 26023140

• Mechano-Transduction: From Molecules to Tissues PLOS BIOLOGY Pruitt, B. L., Dunn, A. R., Weis, W. I., Nelson, W. J. 2014; 12 (11)

  View details for DOI 10.1371/journal.pbio.1001996

  View details for Web of Science ID 000345627300009

• Mechano-transduction: from molecules to tissues. PLoS biology Pruitt, B. L., Dunn, A. R., Weis, W. I., Nelson, W. J. 2014; 12 (11)

  Abstract

  External forces play complex roles in cell organization, fate, and homeostasis. Changes in these forces, or how cells respond to them, can result in abnormal embryonic development and diseases in adults. How cells sense and respond to these mechanical stimuli requires an understanding of the biophysical principles that underlie changes in protein conformation and result in alterations in the organization and function of cells and tissues. Here, we discuss mechano-transduction as it applies to protein conformation, cellular organization, and multi-cell (tissue) function.

  View details for DOI 10.1371/journal.pbio.1001996

  View details for PubMedID 25405923

• Stable, Covalent Attachment of Laminin to Microposts Improves the Contractility of Mouse Neonatal Cardiomyocytes ACS APPLIED MATERIALS & INTERFACES Ribeiro, A. J., Zaleta-Rivera, K., Ashley, E. A., Pruitt, B. L. 2014; 6 (17): 15516-15526

  View details for Web of Science ID 000341544200092

• Stable, covalent attachment of laminin to microposts improves the contractility of mouse neonatal cardiomyocytes. ACS applied materials & interfaces Ribeiro, A. J., Zaleta-Rivera, K., Ashley, E. A., Pruitt, B. L. 2014; 6 (17): 15516-15526

  Abstract

  The mechanical output of contracting cardiomyocytes, the muscle cells of the heart, relates to healthy and disease states of the heart. Culturing cardiomyocytes on arrays of elastomeric microposts can enable inexpensive and high-throughput studies of heart disease at the single-cell level. However, cardiomyocytes weakly adhere to these microposts, which limits the possibility of using biomechanical assays of single cardiomyocytes to study heart disease. We hypothesized that a stable covalent attachment of laminin to the surface of microposts improves cardiomyocyte contractility. We cultured cells on polydimethylsiloxane microposts with laminin covalently bonded with the organosilanes 3-glycidoxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane with glutaraldehyde. We measured displacement of microposts induced by the contractility of mouse neonatal cardiomyocytes, which attach better than mature cardiomyocytes to substrates. We observed time-dependent changes in contractile parameters such as micropost deformation, contractility rates, contraction and relaxation speeds, and the times of contractions. These parameters were affected by the density of laminin on microposts and by the stability of laminin binding to micropost surfaces. Organosilane-mediated binding resulted in higher laminin surface density and laminin binding stability. 3-glycidoxypropyltrimethoxysilane provided the highest laminin density but did not provide stable protein binding with time. Higher surface protein binding stability and strength were observed with 3-aminopropyltriethoxysilane with glutaraldehyde. In cultured cardiomyocytes, contractility rate, contraction speeds, and contraction time increased with higher laminin stability. Given these variations in contractile function, we conclude that binding of laminin to microposts via 3-aminopropyltriethoxysilane with glutaraldehyde improves contractility observed by an increase in beating rate and contraction speed as it occurs during the postnatal maturation of cardiomyocytes. This approach is promising for future studies to mimic in vivo tissue environments.

  View details for DOI 10.1021/am5042324

  View details for PubMedID 25133578

• Shielded piezoresistive cantilever probes for nanoscale topography and electrical imaging JOURNAL OF MICROMECHANICS AND MICROENGINEERING Yang, Y., Ma, E. Y., Cui, Y., Haemmerli, A., Lai, K., Kundhikanjana, W., Harjee, N., Pruitt, B. L., Kelly, M., Shen, Z. 2014; 24 (4)

  View details for DOI 10.1088/0960-1317/24/4/045026

  View details for Web of Science ID 000334306100025

• Multifunctional integrated sensor in a 2x2 mm epitaxial sealed chip operating in a wireless sensor node Roozeboom, C., L., Hong, V., A., Ahn, C., H., Ng, E., J., Yang, Y., Hill, B., E., Pruitt, B. 2014
• Planar patterned stretchable electrode arrays based on flexible printed circuits JOURNAL OF MICROMECHANICS AND MICROENGINEERING Taylor, R. E., BOYCE, C. M., Boyce, M. C., Pruitt, B. L. 2013; 23 (10)

  View details for DOI 10.1088/0960-1317/23/10/105004

  View details for Web of Science ID 000324672700005

• MEMS-based shear characterization of soft hydrated samples JOURNAL OF MICROMECHANICS AND MICROENGINEERING Higgs, G. C., Simmons, C. S., Gao, Y., Fried, A. T., Park, S., Chung, C., Pruitt, B. L. 2013; 23 (8)

  View details for DOI 10.1088/0960-1317/23/8/085001

  View details for Web of Science ID 000322221100003

• Nanomechanical Actuation of a Silicon Cantilever Using an Azo Dye, Self-Assembled Monolayer LANGMUIR Rastegar, A. J., Vosgueritchian, M., Doll, J. C., Mallon, J. R., Pruitt, B. L. 2013; 29 (23): 7118-7124

  Abstract

  The emerging fields of nanomotors and optomechanics are based on the harnessing of light to generate force. However, our ability to detect small surface stresses is limited by temperature drift, environmental noise, and low-frequency flicker electronic noise. To address these limitations, we functionalized microfabricated silicon cantilevers with an azo dye, silane-based self-assembled monolayer and modulated the surface stress by exciting the optical switch with a 405-nm laser. Atomic force microscopy, contact angle analysis, ellipsometry, and X-ray photoelectron spectroscopy verified successful assembly of molecules on the cantilever. Ultraviolet and visible spectra demonstrate optical switching of the synthesized molecule in solution. By turning the laser on and off at a specific rate (e.g., 1 Hz), the cantilever deflection can be measured via Fourier techniques, thus separating the signal of interest from the noise. This technique empowers the design of highly sensitive surface stress measurements.

  View details for DOI 10.1021/la3034676

  View details for Web of Science ID 000320485400042

  View details for PubMedID 23663108

• Integrated Multifunctional Environmental Sensors JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Roozeboom, C. L., Hopcroft, M. A., Smith, W. S., Sim, J. Y., Wickeraad, D. A., Hartwell, P. G., Pruitt, B. L. 2013; 22 (3): 779-793

  View details for DOI 10.1109/JMEMS.2013.2245400

  View details for Web of Science ID 000319827700030

• Spatially Resolved Study of Backscattering in the Quantum Spin Hall State PHYSICAL REVIEW X Koenig, M., Baenninger, M., Garcia, A. G., Harjee, N., Pruitt, B. L., Ames, C., Leubner, P., Bruene, C., Buhmann, H., Molenkamp, L. W., Goldhaber-Gordon, D. 2013; 3 (2)

  View details for DOI 10.1103/PhysRevX.3.021003

  View details for Web of Science ID 000317918200001

• Spatial patterning of endothelium modulates cell morphology, adhesiveness and transcriptional signature BIOMATERIALS Huang, N. F., Lai, E. S., Ribeiro, A. J., Pan, S., Pruitt, B. L., Fuller, G. G., Cooke, J. P. 2013; 34 (12): 2928-2937

  Abstract

  Microscale and nanoscale structures can spatially pattern endothelial cells (ECs) into parallel-aligned organization, mimicking their cellular alignment in blood vessels exposed to laminar shear stress. However, the effects of spatial patterning on the function and global transcriptome of ECs are incompletely characterized. We used both parallel-aligned micropatterned and nanopatterned biomaterials to evaluate the effects of spatial patterning on the phenotype of ECs, based on gene expression profiling, functional characterization of monocyte adhesion, and quantification of cellular morphology. We demonstrate that both micropatterned and aligned nanofibrillar biomaterials could effectively guide EC organization along the direction of the micropatterned channels or nanofibrils, respectively. The ability of ECs to sense spatial patterning cues were abrogated in the presence of cytoskeletal disruption agents. Moreover, both micropatterned and aligned nanofibrillar substrates promoted an athero-resistant EC phenotype by reducing endothelial adhesiveness for monocytes and platelets, as well as by downregulating the expression of adhesion proteins and chemokines. We further found that micropatterned ECs have a transcriptional signature that is unique from non-patterned ECs, as well as from ECs aligned by shear stress. These findings highlight the importance of spatial patterning cues in guiding EC organization and function, which may have clinical relevance in the development of vascular grafts that promote patency.

  View details for DOI 10.1016/j.biomaterials.2013.01.017

  View details for Web of Science ID 000316038900008

  View details for PubMedID 23357369

• Sacrificial layer technique for axial force post assay of immature cardiomyocytes BIOMEDICAL MICRODEVICES Taylor, R. E., Kim, K., Sun, N., Park, S., Sim, J. Y., Fajardo, G., Bernstein, D., Wu, J. C., Pruitt, B. L. 2013; 15 (1): 171-181

  Abstract

  Immature primary and stem cell-derived cardiomyocytes provide useful models for fundamental studies of heart development and cardiac disease, and offer potential for patient specific drug testing and differentiation protocols aimed at cardiac grafts. To assess their potential for augmenting heart function, and to gain insight into cardiac growth and disease, tissue engineers must quantify the contractile forces of these single cells. Currently, axial contractile forces of isolated adult heart cells can only be measured by two-point methods such as carbon fiber techniques, which cannot be applied to neonatal and stem cell-derived heart cells because they are more difficult to handle and lack a persistent shape. Here we present a novel axial technique for measuring the contractile forces of isolated immature cardiomyocytes. We overcome cell manipulation and patterning challenges by using a thermoresponsive sacrificial support layer in conjunction with arrays of widely separated elastomeric microposts. Our approach has the potential to be high-throughput, is functionally analogous to current gold-standard axial force assays for adult heart cells, and prescribes elongated cell shapes without protein patterning. Finally, we calibrate these force posts with piezoresistive cantilevers to dramatically reduce measurement error typical for soft polymer-based force assays. We report quantitative measurements of peak contractile forces up to 146 nN with post stiffness standard error (26 nN) far better than that based on geometry and stiffness estimates alone. The addition of sacrificial layers to future 2D and 3D cell culture platforms will enable improved cell placement and the complex suspension of cells across 3D constructs.

  View details for DOI 10.1007/s10544-012-9710-3

  View details for Web of Science ID 000313517800018

• Microactuator device for integrated measurement of epithelium mechanics BIOMEDICAL MICRODEVICES Mukundan, V., Nelson, W. J., Pruitt, B. L. 2013; 15 (1): 117-123

  Abstract

  Mechanical forces are among important factors that drive cellular function and organization. We present a microfabricated device with on-chip actuation for mechanical testing of single cells. An integrated immersible electrostatic actuator system is demonstrated that applies calibrated forces to cells. We conduct stretching experiments by directly applying forces to epithelial cells adhered to device surfaces functionalized with collagen. We measure mechanical properties including stiffness, hysteresis and visco-elasticity of adherent cells.

  View details for DOI 10.1007/s10544-012-9693-0

  View details for Web of Science ID 000313517800012

  View details for PubMedID 22927158

• Characterization of the Biophysical Origins of Mechanical Homeostasis at Cellular Adhesions Mekhdjian, A. H., Morimatsu, M., Borghi, N., Pruitt, B. L., Weis, W. I., Nelson, W. J., Dunn, A. R. CELL PRESS. 2013: 491A-491A

  View details for Web of Science ID 000316074304489

• Abnormal Calcium Handling Properties Underlie Familial Hypertrophic Cardiomyopathy Pathology in Patient-Specific Induced Pluripotent Stem Cells CELL STEM CELL Lan, F., Lee, A. S., Liang, P., Sanchez-Freire, V., Nguyen, P. K., Wang, L., Han, L., Yen, M., Wang, Y., Sun, N., Abilez, O. J., Hu, S., Ebert, A. D., Navarrete, E. G., Simmons, C. S., Wheeler, M., Pruitt, B., Lewis, R., Yamaguchi, Y., Ashley, E. A., Bers, D. M., Robbins, R. C., Longaker, M. T., Wu, J. C. 2013; 12 (1): 101-113

  Abstract

  Familial hypertrophic cardiomyopathy (HCM) is a prevalent hereditary cardiac disorder linked to arrhythmia and sudden cardiac death. While the causes of HCM have been identified as genetic mutations in the cardiac sarcomere, the pathways by which sarcomeric mutations engender myocyte hypertrophy and electrophysiological abnormalities are not understood. To elucidate the mechanisms underlying HCM development, we generated patient-specific induced pluripotent stem cell cardiomyocytes (iPSC-CMs) from a ten-member family cohort carrying a hereditary HCM missense mutation (Arg663His) in the MYH7 gene. Diseased iPSC-CMs recapitulated numerous aspects of the HCM phenotype including cellular enlargement and contractile arrhythmia at the single-cell level. Calcium (Ca(2+)) imaging indicated dysregulation of Ca(2+) cycling and elevation in intracellular Ca(2+) ([Ca(2+)](i)) are central mechanisms for disease pathogenesis. Pharmacological restoration of Ca(2+) homeostasis prevented development of hypertrophy and electrophysiological irregularities. We anticipate that these findings will help elucidate the mechanisms underlying HCM development and identify novel therapies for the disease.

  View details for DOI 10.1016/j.stem.2012.10.010

  View details for Web of Science ID 000313839500014

• MEMS-based force-clamp analysis of the role of body stiffness in C. elegans touch sensation INTEGRATIVE BIOLOGY Petzold, B. C., Park, S., Mazzochette, E. A., Goodman, M. B., Pruitt, B. L. 2013; 5 (6): 853-864

  Abstract

  Touch is enabled by mechanoreceptor neurons in the skin and plays an essential role in our everyday lives, but is among the least understood of our five basic senses. Force applied to the skin deforms these neurons and activates ion channels within them. Despite the importance of the mechanics of the skin in determining mechanoreceptor neuron deformation and ultimately touch sensation, the role of mechanics in touch sensitivity is poorly understood. Here, we use the model organism Caenorhabditis elegans to directly test the hypothesis that body mechanics modulate touch sensitivity. We demonstrate a microelectromechanical system (MEMS)-based force clamp that can apply calibrated forces to freely crawling C. elegans worms and measure touch-evoked avoidance responses. This approach reveals that wild-type animals sense forces <1 μN and indentation depths <1 μm. We use both genetic manipulation of the skin and optogenetic modulation of body wall muscles to alter body mechanics. We find that small changes in body stiffness dramatically affect force sensitivity, while having only modest effects on indentation sensitivity. We investigate the theoretical body deformation predicted under applied force and conclude that local mechanical loads induce inward bending deformation of the skin to drive touch sensation in C. elegans.

  View details for DOI 10.1039/c3ib20293c

  View details for Web of Science ID 000319571600002

• Spontaneous cardiomyocyte differentiation of mouse embryoid bodies regulated by hydrogel crosslink density Biomaterials Science Chung, C., Pruitt, B., L., Heilshorn, S., C. 2013; 10 (1): 1082 - 1090

  View details for DOI 10.1039/C3BM60139K

• The Yin-Yang of Rigidity Sensing: How Forces and Mechanical Properties Regulate the Cellular Response to Materials ANNUAL REVIEW OF MATERIALS RESEARCH, VOL 43 Schoen, I., Pruitt, B. L., Vogel, V. 2013; 43: 589-618

  View details for DOI 10.1146/annurev-matsci-062910-100407

  View details for Web of Science ID 000323892700023

• Microsystems AND Functional Assay for Mechanobiology Pruitt, B., L., Doll, J., C., Park, S., J., Harjee, N., Petzold, B., C. 2013
• Spatial patterning of endothelium modulates cell morphology, adhesiveness and transcriptional signature Biomaterials Huang, N., F., Lai, E., S., Ribeiro, A., J., Pan, S., Pruitt, B., L., Fuller, G., G. 2013; 34 (12): 2928-37

  View details for DOI 10.1016/j.biomaterials.2013.01.017

• Spatially Resolved Study of Backscattering in the Quantum Spin Hall State Physical Review X Koenig, M., Baenninger, M., Garcia, A., G. F., Harjee, N., Pruitt, B., L., Ames, C. 2013; 3: 21003

  View details for DOI 10.1103/PhysRevX.3.021003

• A Real Time Imaging System for Tracking Freely Moving C. elegans in Touch Assays Mazzochette, E., A., Yen, C., Fang, Goodman, M., B., Pruitt, B., L. 2013
• Ultra-Thin Atomic Layer Deposition Films for Corrosion Resistance Haemmerli, A., J., Doll, J., C., Provine, J., Howe, R., T., Pruitt, B., L. 2013
• Inducing variations in the shortening of single cardiomyocytes with localized mechanical stimulation Higgs, G., C., Ribeiro, A., J. S., Zaleta, K., Ashley, E., A., Pruitt, B., L. 2013
• The Yin-Yang of Rigidity Sensing: How Forces and Mechanical Properties Regulate the Cellular Response to Materials Annual Review of Materials Research Schoen, I., Pruitt, B., L., Vogel, V. 2013

  View details for DOI 10.1146/annurev-matsci-062910-100407

• MEMS-based force-clamp analysis of the role of body stiffness in C. elegans touch sensation Integrative Biology Petzold, B., C., Park, S. -J., Mazzochette, E., A., Goodman, M., B., Pruitt, B., L. 2013; 5 (6): 853-64

  View details for DOI 10.1039/C3IB20293C

• MEMS-based shear characterization of soft hydrated samples Journal of Micromechanics and Microengineering Higgs, G., C., Simmons, C., S., Gao, Y., Fried, A., T., Park, S., J., Chung, C., Pruitt, B. 2013; 8 (23): 85001

  View details for DOI 10.1088/0960-1317/23/8/085001

• Planar patterned stretchable electrode arrays based on flexible printed circuits Journal of Micromechanics and Microengineering, 23, 105004 (2013) *Article chosen for IOP Select Distribution due to its novelty, significance and potential impact on future research Taylor, R., E., Boyce, C., M., Boyce, M., C., Pruitt, B., L. 2013; 23: 105004
• Nanomechanical Actuation of a Silicon Cantilever Using an Azo Dye, Self-Assembled Monolayer Langmuir Rastegar, A., Joseph, Vosgueritchian, M., Doll, J., C., Mallon, J., R., Pruitt, B., L. 2013; 23 (29): 6779-7178

  View details for DOI 10.1021/la3034676

• Spontaneous cardiomyocyte differentiation of mouse embryoid bodies regulated by hydrogel crosslink density BIOMATERIALS SCIENCE Chung, C., Pruitt, B. L., Heilshorn, S. C. 2013; 1 (10): 1082-1090

  View details for DOI 10.1039/c3bm60139k

  View details for Web of Science ID 000330137700009

• Integrated Sensor Cross-Sensitivity Analysis Roozeboom, C., L., Salgado, J., F., Hopcroft, M., A., Pruitt, B., L. 2013
• Piezoresistor Design and Applications Doll, J. C., Pruitt, B. L. Springer. 2013
• PIEZORESISTIVE CANTILEVER PROBES FOR SIMULTANEOUS NANOSCALE TOPOGRAPHY AND CONDUCTIVITY IMAGING 26TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2013) Yang, Y., Ma, Y., Haemmerli, A., Lai, K., Kundhikanjana, W., Harjee, N., Pruitt, B., Li, X., Kelly, M., Shen, Z. 2013: 323-326

  View details for Web of Science ID 000320549200083

• Formation of composite polyacrylamide and silicone substrates for independent control of stiffness and strain LAB ON A CHIP Simmons, C. S., Ribeiro, A. J., Pruitt, B. L. 2013; 13 (4): 646-649

  Abstract

  Cells that line major tissues in the body such as blood vessels, lungs and gastrointestinal tract experience deformation from mechanical strain with our heartbeat, breathing, and other daily activities. Tissues also remodel in both development and disease, changing their mechanical properties. Taken together, cells can experience vastly different mechanical cues resulting from the combination of these interdependent stimuli. To date, most studies of cellular mechanotransduction have been limited to assays in which variations in substrate stiffness and strain were not combined. Here, we address this technological gap by implementing a method that can simultaneously tune both substrate stiffness and mechanical strain. Substrate stiffness is controlled with different monomer and crosslinker ratios during polyacrylamide gel polymerization, and strain is transferred from the underlying silicone platform when stretched. We demonstrate this platform with polyacrylamide gels with elastic moduli at 6 kPa and 20 kPa in combination with two different silicone formulations. The gels remain attached with up to 50% applied strains. To validate strain transfer through the gels into cells, we employ particle-tracking methods and observe strain transmission via cell morphological changes.

  View details for DOI 10.1039/c2lc41110e

  View details for Web of Science ID 000313971300019

  View details for PubMedID 23287818

• Faster than the Speed of Hearing: Nanomechanical Force Probes Enable the Electromechanical Observation of Cochlear Hair Cells NANO LETTERS Doll, J. C., Peng, A. W., Ricci, A. J., Pruitt, B. L. 2012; 12 (12): 6107-6111

  Abstract

  Understanding the mechanisms responsible for our sense of hearing requires new tools for unprecedented stimulation and monitoring of sensory cell mechanotransduction at frequencies yet to be explored. We describe nanomechanical force probes designed to evoke mechanotransduction currents at up to 100 kHz in living cells. High-speed force and displacement metrology is enabled by integrating piezoresistive sensors and piezoelectric actuators onto nanoscale cantilevers. The design, fabrication process, actuator performance, and actuator-sensor crosstalk compensation results are presented. We demonstrate the measurement of mammalian cochlear hair cell mechanotransduction with simultaneous patch clamp recordings at unprecedented speeds. The probes can deliver mechanical stimuli with sub-10 ?s rise times in water and are compatible with standard upright and inverted microscopes.

  View details for DOI 10.1021/nl3036349

  View details for Web of Science ID 000312122100012

  View details for PubMedID 23181721

• High-bandwidth piezoresistive force probes with integrated thermal actuation Doll, J. C., Pruitt, B. L. IOP PUBLISHING LTD. 2012

  View details for DOI 10.1088/0960-1317/22/9/095012

  View details for Web of Science ID 000308210600022

• E-cadherin is under constitutive actomyosin-generated tension that is increased at cell-cell contacts upon externally applied stretch PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Borghi, N., Sorokina, M., Shcherbakova, O. G., Weis, W. I., Pruitt, B. L., Nelson, W. J., Dunn, A. R. 2012; 109 (31): 12568-12573

  Abstract

  Classical cadherins are transmembrane proteins at the core of intercellular adhesion complexes in cohesive metazoan tissues. The extracellular domain of classical cadherins forms intercellular bonds with cadherins on neighboring cells, whereas the cytoplasmic domain recruits catenins, which in turn associate with additional cytoskeleton binding and regulatory proteins. Cadherin/catenin complexes are hypothesized to play a role in the transduction of mechanical forces that shape cells and tissues during development, regeneration, and disease. Whether mechanical forces are transduced directly through cadherins is unknown. To address this question, we used a Förster resonance energy transfer (FRET)-based molecular tension sensor to test the origin and magnitude of tensile forces transmitted through the cytoplasmic domain of E-cadherin in epithelial cells. We show that the actomyosin cytoskeleton exerts pN-tensile force on E-cadherin, and that this tension requires the catenin-binding domain of E-cadherin and ?E-catenin. Surprisingly, the actomyosin cytoskeleton constitutively exerts tension on E-cadherin at the plasma membrane regardless of whether or not E-cadherin is recruited to cell-cell contacts, although tension is further increased at cell-cell contacts when adhering cells are stretched. Our findings thus point to a constitutive role of E-cadherin in transducing mechanical forces between the actomyosin cytoskeleton and the plasma membrane, not only at cell-cell junctions but throughout the cell surface.

  View details for DOI 10.1073/pnas.1204390109

  View details for Web of Science ID 000307538200062

  View details for PubMedID 22802638

• Low-impedance shielded tip piezoresistive probe enables portable microwave impedance microscopy MICRO & NANO LETTERS Haemmerli, A. J., Nielsen, R. T., Kundhikanjana, W., HARJEE, N., Goldhaber-Gordon, D., Shen, Z. X., Pruitt, B. L. 2012; 7 (4): 321-324

  View details for DOI 10.1049/mnl.2011.0679

  View details for Web of Science ID 000303341600008

• SPECIAL SECTION: MICRO AND NANO TECHNOLOGIES FOR PROBE-BASED MICROSCOPY MICRO & NANO LETTERS Curri, L., Fedder, G., Pruitt, B. L. 2012; 7 (4): 296-296

  View details for DOI 10.1049/mnl.2012.0244

  View details for Web of Science ID 000303341600001

• Hydrogel crosslinking density regulates temporal contractility of human embryonic stem cell-derived cardiomyocytes in 3D cultures SOFT MATTER Chung, C., Anderson, E., Pera, R. R., Pruitt, B. L., Heilshorn, S. C. 2012; 8 (39): 10141-10148

  Abstract

  Systematically tunable in vitro platforms are invaluable in gaining insight to stem cell-microenvironment interactions in three-dimensional cultures. Utilizing recombinant protein technology, we independently tune hydrogel properties to systematically isolate the effects of matrix crosslinking density on cardiomyocyte differentiation, maturation, and function. We show that contracting human embryonic stem cell-derived cardiomyocytes (hESC-CMs) remain viable within four engineered elastin-like hydrogels of varying crosslinking densities with elastic moduli ranging from 0.45 to 2.4 kPa. Cardiomyocyte phenotype and function was maintained within hESC embryoid bodies for up to 2 weeks. Interestingly, increased crosslinking density was shown to transiently suspend spontaneous contractility. While encapsulated cells began spontaneous contractions at day 1 in hydrogels of the lowest crosslinking density, onset of contraction was increasingly delayed at higher crosslinking densities up to 6 days. However, once spontaneous contraction was restored, the rate of contraction was similar within all materials (71 ± 8 beats/min). Additionally, all groups successfully responded to electrical pacing at both 1 and 2 Hz. This study demonstrates that encapsulated hESC-CMs respond to 3D matrix crosslinking density within elastin-like hydrogels and stresses the importance of investigating temporal cellular responses in 3D cultures.

  View details for DOI 10.1039/c2sm26082d

  View details for Web of Science ID 000308882800024

• Influence of body mechanics on force thresholds for touch sensation in C. elegans Petzold, B., C., Park, S. -J., Ponce, P., Roozeboom, C., Powell, C., Goodman, M., B., Pruitt, B. 2012
• Body mechanics regulate the force threshold for gentle touch sensation in the nematode C. elegans Petzold, B., C., Park, S. -J., Goodman, M., B., Pruitt, B., L. 2012
• Low-Impedance Shielded Tip Piezoresistive Probe Enables Portable Microwave Impedance Microscopy Micro & Nano Letters Haemmerli, A., J., Nielsen, R., T., Kundhikanjana, W., Harjee, N., Goldhaber-Gordon, D., Shen, Z., X., Pruitt, B. 2012; 7 (4): 321–324

  View details for DOI 10.1049/mnl.2011.0679

• Sacrificial layer technique for axial force post assay of immature cardiomyocytes Biomedical Microdevices Taylor, R., Kim, K., Sun, N., Park, S-j., Sim, J., Y., Fajardo, G., Pruitt, B. 2012; 15 (1): 171-181

  View details for DOI 10.1007/s10544-012-9710-3

• Covalent Attachment of Bioactive Molecules to PDMS for Cardiomyocyte Adhesion Ribeiro, A., J.S., Rastegar, A., J., Zaleta, K., Ashley, E., A., Pruitt, B., L. 2012
• Effects of substrate mechanics on contractility of cardiomyocytes generated from human pluripotent stem cells International Journal of Cell Biology Hazeltine, L., Simmons, C., S., Salick, M., Lian, X., Badur, M., Han, W., Pruitt, B. 2012: 508294
• High bandwidth piezoresistive force probes with integrated thermal actuation Journal of Micromechanics and Microengineering Doll, J., C., Pruitt, B., L. 2012; 22 (9): 95012
• Formation of composite polyacrylamide and silicone substrates for independent control of stiffness and strain Lab Chip Simmons, C., S., Ribeiro, A., J.S., Pruitt, B., L. 2012; 13: 646-649

  View details for DOI 10.1039/C2LC41110E

• Piezoresistive Cantilevers for Biological Force Measurements Doll, J., C., Park, S. -J., Harjee, N., Petzold, B., C., Pruitt, B., L. 2012
• MEMS force probes for cell mechanobiology at the microsecond scale Doll, J., C., Pruitt, B., L. 2012
• Changes in Cell Traction Forces in Response to Uniaxial Loading Sim, J., Y., Borghi, N., Kim, K., Simmons, C., S., Ribeiro, A., J.S., Pruitt, B., L. 2012
• MULTI-FUNCTIONAL INTEGRATED SENSORS FOR THE ENVIRONMENT 2012 IEEE 25TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS) Roozeboom, C. L., Sim, J. Y., Wickeraad, D., Dura, B., Smith, W. S., Hopcroft, M. A., Hartwell, P. G., Williams, R. S., Pruitt, B. L. 2012

  View details for Web of Science ID 000312912800038

• UNIAXIAL CELL STRETCHER ENABLES HIGH RESOLUTION LIVE CELL IMAGING 2012 IEEE 25TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS) Sim, J. Y., Borghi, N., RIBEIRO, A., Sorokina, M., Shcherbakova, O., Ramallo, D., Dunn, A., NELSON, W. J., Pruitt, B. L. 2012

  View details for Web of Science ID 000312912800215

• LOW-IMPEDANCE SHIELDED TIP PIEZORESISTIVE PROBE ENABLES PORTABLE MICROWAVE IMPEDANCE MICROSCOPY Haemmerli, A. J., Nielsen, R. T., Kundhikanjana, W., HARJEE, N., Lai, K., Yang, Y. L., Goldhaber-Gordon, D., Shen, Z. X., Pruitt, B. L. IEEE. 2012

  View details for Web of Science ID 000312912800070

• High bandwidth piezoresistive force probes with integrated thermal actuation. Journal of micromechanics and microengineering : structures, devices, and systems Doll, J. C., Pruitt, B. L. 2012; 22 (9)

  Abstract

  We present high-speed force probes with on-chip actuation and sensing for the measurement of pN-scale forces at the microsecond time scale. We achieve a high resonant frequency in water (1-100 kHz) with requisite low spring constants (0.3-40 pN/nm) and low integrated force noise (1-100 pN) by targeting probe dimensions on the order of 300 nm thick, 1-2 ?m wide and 30-200 ?m long. Forces are measured using silicon piezoresistors while the probes are actuated thermally with an aluminum unimorph and silicon heater. The piezoresistive sensors are designed using open source numerical optimization code that incorporates constraints on operating temperature. Parylene passivation enables operation in ionic media and we demonstrate simultaneous actuation and sensing. The improved design and fabrication techniques that we describe enable a 10-20 fold improvement in force resolution or measurement bandwidth over prior piezoresistive cantilevers of comparable thickness.

  View details for PubMedID 23175616

• Low-Impedance Shielded Tip Piezoresistive Probe Enables Portable Microwave Impedance Microscopy Micro Nano Letters A.J. Haemmerli, R.T. Nielsen, W. Kundhikanjana, N. Harjee, D. Goldhaber-Gordon, Z.X. Shen, B.L. Pruitt 2012; 7 (4): 321?324
• Effects of substrate mechanics on contractility of cardiomyocytes generated from human pluripotent stem cells. International journal of cell biology Hazeltine, L. B., Simmons, C. S., Salick, M. R., Lian, X., Badur, M. G., Han, W., Delgado, S. M., Wakatsuki, T., Crone, W. C., Pruitt, B. L., Palecek, S. P. 2012; 2012: 508294-?

  Abstract

  Human pluripotent stem cell (hPSC-) derived cardiomyocytes have potential applications in drug discovery, toxicity testing, developmental studies, and regenerative medicine. Before these cells can be reliably utilized, characterization of their functionality is required to establish their similarity to native cardiomyocytes. We tracked fluorescent beads embedded in 4.4-99.7?kPa polyacrylamide hydrogels beneath contracting neonatal rat cardiomyocytes and cardiomyocytes generated from hPSCs via growth-factor-induced directed differentiation to measure contractile output in response to changes in substrate mechanics. Contraction stress was determined using traction force microscopy, and morphology was characterized by immunocytochemistry for ?-actinin and subsequent image analysis. We found that contraction stress of all types of cardiomyocytes increased with substrate stiffness. This effect was not linked to beating rate or morphology. We demonstrated that hPSC-derived cardiomyocyte contractility responded appropriately to isoprenaline and remained stable in culture over a period of 2 months. This study demonstrates that hPSC-derived cardiomyocytes have appropriate functional responses to substrate stiffness and to a pharmaceutical agent, which motivates their use in further applications such as drug evaluation and cardiac therapies.

  View details for DOI 10.1155/2012/508294

  View details for PubMedID 22649451

• Microsystems for biomimetic stimulation of cardiac cells LAB ON A CHIP Simmons, C. S., Petzold, B. C., Pruitt, B. L. 2012; 12 (18): 3235-3248

  Abstract

  The heart is a complex integrated system that leverages mechanoelectrical signals to synchronize cardiomyocyte contraction and push blood throughout the body. The correct magnitude, timing, and distribution of these signals is critical for proper functioning of the heart; aberrant signals can lead to acute incidents, long-term pathologies, and even death. Due to the heart's limited regenerative capacity and the wide variety of pathologies, heart disease is often studied in vitro. However, it is difficult to accurately replicate the cardiac environment outside of the body. Studying the biophysiology of the heart in vitro typically consists of studying single cells in a tightly controlled static environment or whole tissues in a complex dynamic environment. Micro-electromechanical systems (MEMS) allow us to bridge these two extremes by providing increasing complexity for cell culture without having to use a whole tissue. Here, we carefully describe the electromechanical environment of the heart and discuss MEMS specifically designed to replicate these stimulation modes. Strengths, limitations and future directions of various designs are discussed for a variety of applications.

  View details for DOI 10.1039/c2lc40308k

  View details for Web of Science ID 000307583400002

  View details for PubMedID 22782590

• DEG/ENaC but Not TRP Channels Are the Major Mechanoelectrical Transduction Channels in a C. elegans Nociceptor NEURON Geffeney, S. L., Cueva, J. G., Glauser, D. A., Doll, J. C., Lee, T. H., Montoya, M., Karania, S., Garakani, A. M., Pruitt, B. L., Goodman, M. B. 2011; 71 (5): 845-857

  Abstract

  Many nociceptors detect mechanical cues, but the ion channels responsible for mechanotransduction in these sensory neurons remain obscure. Using in vivo recordings and genetic dissection, we identified the DEG/ENaC protein, DEG-1, as the major mechanotransduction channel in ASH, a polymodal nociceptor in Caenorhabditis elegans. But DEG-1 is not the only mechanotransduction channel in ASH: loss of deg-1 revealed a minor current whose properties differ from those expected of DEG/ENaC channels. This current was independent of two TRPV channels expressed in ASH. Although loss of these TRPV channels inhibits behavioral responses to noxious stimuli, we found that both mechanoreceptor currents and potentials were essentially wild-type in TRPV mutants. We propose that ASH nociceptors rely on two genetically distinct mechanotransduction channels and that TRPV channels contribute to encoding and transmitting information. Because mammalian and insect nociceptors also coexpress DEG/ENaCs and TRPVs, the cellular functions elaborated here for these ion channels may be conserved.

  View details for DOI 10.1016/j.neuron.2011.06.038

  View details for Web of Science ID 000294877900010

  View details for PubMedID 21903078

• Patterned cracks improve yield in the release of compliant microdevices from silicon-on-insulator wafers JOURNAL OF MICROMECHANICS AND MICROENGINEERING Hill, G. C., Padovani, J. I., Doll, J. C., Chui, B. W., Rugar, D., Mamin, H. J., HARJEE, N., Pruitt, B. L. 2011; 21 (8)

  View details for DOI 10.1088/0960-1317/21/8/087001

  View details for Web of Science ID 000293163700038

• Self-heating in piezoresistive cantilevers APPLIED PHYSICS LETTERS Doll, J. C., Corbin, E. A., King, W. P., Pruitt, B. L. 2011; 98 (22)

  View details for DOI 10.1063/1.3595485

  View details for Web of Science ID 000291405700053

• Stretchable microelectrode array using room-temperature liquid alloy interconnects JOURNAL OF MICROMECHANICS AND MICROENGINEERING Wei, P., Taylor, R., Ding, Z., Chung, C., Abilez, O. J., Higgs, G., Pruitt, B. L., Ziaie, B. 2011; 21 (5)

  View details for DOI 10.1088/0960-1317/21/5/054015

  View details for Web of Science ID 000289986600016

• Integrated strain array for cellular mechanobiology studies JOURNAL OF MICROMECHANICS AND MICROENGINEERING Simmons, C. S., Sim, J. Y., Baechtold, P., Gonzalez, A., Chung, C., Borghi, N., Pruitt, B. L. 2011; 21 (5)

  View details for DOI 10.1088/0960-1317/21/5/054016

  View details for Web of Science ID 000289986600017

• Calibrated micropost arrays for biomechanical characterisation of cardiomyocytes MICRO & NANO LETTERS Kim, K., Taylor, R., Sim, J. Y., Park, S., Norman, J., Fajardo, G., Bernstein, D., Pruitt, B. L. 2011; 6 (5): 317-322

  View details for DOI 10.1049/mnl.2011.0031

  View details for Web of Science ID 000290764000007

• MEMS in biology and medicine JOURNAL OF MICROMECHANICS AND MICROENGINEERING Pruitt, B. L., Herr, A. E. 2011; 21 (5)

  View details for DOI 10.1088/0960-1317/21/5/050201

  View details for Web of Science ID 000289986600001

• Caenorhabditis elegans Body Mechanics Are Regulated by Body Wall Muscle Tone BIOPHYSICAL JOURNAL Petzold, B. C., Park, S., Ponce, P., Roozeboom, C., Powell, C., Goodman, M. B., Pruitt, B. L. 2011; 100 (8): 1977-1985

  Abstract

  Body mechanics in the nematode Caenorhabditis elegans are central to both mechanosensation and locomotion. Previous work revealed that the mechanics of the outer shell, rather than internal hydrostatic pressure, dominates stiffness. This shell is comprised of the cuticle and the body wall muscles, either of which could contribute to the body mechanics. Here, we tested the hypothesis that the muscles are an important contributor by modulating muscle tone using optogenetic and pharmacological tools, and measuring animal stiffness using piezoresistive microcantilevers. As a proxy for muscle tone, we measured changes in animal length under the same treatments. We found that treatments that induce muscle contraction generally resulted in body shortening and stiffening. Conversely, methods to relax the muscles more modestly increased length and decreased stiffness. The results support the idea that body wall muscle activation contributes significantly to and can modulate C. elegans body mechanics. Modulation of body stiffness would enable nematodes to tune locomotion or swimming gaits and may have implications in touch sensation.

  View details for DOI 10.1016/j.bpj.2011.02.035

  View details for Web of Science ID 000289864100017

  View details for PubMedID 21504734

• Piezoresistive cantilever force-clamp system REVIEW OF SCIENTIFIC INSTRUMENTS Park, S., Petzold, B. C., Goodman, M. B., Pruitt, B. L. 2011; 82 (4)

  Abstract

  We present a microelectromechanical device-based tool, namely, a force-clamp system that sets or "clamps" the scaled force and can apply designed loading profiles (e.g., constant, sinusoidal) of a desired magnitude. The system implements a piezoresistive cantilever as a force sensor and the built-in capacitive sensor of a piezoelectric actuator as a displacement sensor, such that sample indentation depth can be directly calculated from the force and displacement signals. A programmable real-time controller operating at 100 kHz feedback calculates the driving voltage of the actuator. The system has two distinct modes: a force-clamp mode that controls the force applied to a sample and a displacement-clamp mode that controls the moving distance of the actuator. We demonstrate that the system has a large dynamic range (sub-nN up to tens of ?N force and nm up to tens of ?m displacement) in both air and water, and excellent dynamic response (fast response time, <2 ms and large bandwidth, 1 Hz up to 1 kHz). In addition, the system has been specifically designed to be integrated with other instruments such as a microscope with patch-clamp electronics. We demonstrate the capabilities of the system by using it to calibrate the stiffness and sensitivity of an electrostatic actuator and to measure the mechanics of a living, freely moving Caenorhabditis elegans nematode.

  View details for DOI 10.1063/1.3574362

  View details for Web of Science ID 000290051500022

  View details for PubMedID 21529009

• Effects of substrate mechanics on yield and contractility of cardiomyocytes generated from pluripotent stem cells Hazeltine, L., Simmons, C., Salick, M., Crone, W., Pruitt, B., Palecek, S. AMER CHEMICAL SOC. 2011

  View details for Web of Science ID 000291982801875

• Self-heating in piezoresistive cantilevers. Applied physics letters Doll, J. C., Corbin, E. A., King, W. P., Pruitt, B. L. 2011; 98 (22): 223103

  Abstract

  We report experiments and models of self-heating in piezoresistive microcantilevers that show how cantilever measurement resolution depends on the thermal properties of the surrounding fluid. The predicted cantilever temperature rise from a finite difference model is compared with detailed temperature measurements on fabricated devices. Increasing the fluid thermal conductivity allows for lower temperature operation for a given power dissipation, leading to lower force and displacement noise. The force noise in air is 76% greater than in water for the same increase in piezoresistor temperature.

  View details for PubMedID 21731884

• Stretchable microelectrode array using room-temperature-liquid alloy interconnects JMM Wei, P., Taylor, R., Ding, Z., Chung, C., Abilez, O., J., Higgs, G., Pruitt, B. 2011; 5 (21): 54015
• The functional importance of the MEC-4 transmembrane domain in force activation of the channel Eastwood, A., L., Petzold, B., C., Park, S. -J., Pruitt, B., L., Goodman, M., B. 2011
• Micropost-based Functional Assay of Adult Heart Cells: Does Mechanosensing Limit Force Production? Taylor, R., E., Ribeiro, A., Fajardo, G., Razavi, H., Bernstein, D., Pruitt, B., L. 2011
• Integrated strain array for cellular mechanobiology studies Integrated strain array for cellular mechanobiology studies JMM Simmons, C., S., Sim, J., Y., Baechtold, P., Gonzalez, A., Chung, C., Borghi, N., Pruitt, B. 2011; 5 (21): 54016
• Calibrated micropost arrays for biomechanical characterization of cardiomyocytes Micro and Nano Letters Kim, K., Taylor, R., Sim, J., Y., Park, S. -J., Norman, J., J., Fajardo, G., Pruitt, B. 2011; 5 (6): 317-322
• Parametric Analysis of Strain Effects on Cell-Cell Junctions Sim, J., Y., Simmons, C., Borghi, N., Baechtold, P., Pruitt, B., L. 2011
• Adhesion Proteins for Mechanotransduction Assays Martin, E., F., Chung, C., Sim, J., Y., Pruitt, B., L. 2011
• Tools for studying biomechanical interactions in cells in Mechanobiology of Cell-Cell and Cell-Matrix Interactions Handbook Taylor, R., E., Mukundan, V., Pruitt, B., L. Springer. 2011
• The MEMS Design Process in Handbook of MEMS Materials and Processes Lamers, K., L., Pruitt, B., L. Springer. 2011
• Piezoresistive cantilever force-clamp system Review of Scientific Instruments Park, S. -J., Petzold, B., C., Goodman, M., B., Pruitt, B., L. 2011; 82 (4): 43703
• Characterization of Adhesion Proteins for Cell Mechanotransduction Assays Martin, E., F., Chung, C., Pruitt, B., L. 2011
• An Electrically-Addressable, Liquid Release Well Array for a Hand-held, Scent Dispense System Micro Nano Lett. Lamers, K., L., Chiang, P., Ruby, R., Pruitt, B., L. 2011; 6 (1): 37–38
• Media:Hill_2011_JMM.pdf|Patterned cracks improve yield in the release of compliant microdevices from silicon-on-insulator wafers Journal of Micromechanics and Microengineering Hill, G., C., Padovani, J., I., Doll, J., C., Chui, B., W., Rugar, D., Mamin, H., J., Pruitt, B. 2011; 21
• Self-sensing, coaxial-tip piezoresistive probes for scanning gate and microwave microscopy Harjee, N., Haemmerli, A., König, M., Goldhaber-Gordon, D., Pruitt, B., L. 2011
• DEG/ENaC but not TRP Channels are the major mechanoelectrical transduction channels in a C. elegans nociceptor Neuron Geffeney, S., L., Cueva, J., G., Glauser, D., A., Doll, J., C., Lee, T., H. C., Montoya, M., Pruitt, B. 2011; 71 (5)
• Effects of crosslinking density on viability and maintenance of human embryonic stem cell-derived cardiomyocytes in elastin-like hydrogels Chung, C., Marchand, M., Pruitt, B., Heilshorn, S. 2011
• Self-heating in piezoresistive cantilevers Applied Physics Letters Doll, J., C., Corbin, E., A., King, W., P., Pruitt, B., L. 2011; 98 (22)
• PATTERNED CRACKS IN THE BURIED OXIDE LAYER IMPROVE YIELD IN DEVICE RELEASE FROM SOI WAFERS 2011 IEEE 24TH INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS) Hill, G. C., Padovani, J. I., Chui, B. W., Mamin, H. J., Rugar, D., HARJEE, N., Doll, J. C., Pruitt, B. L. 2011: 300-303

  View details for Web of Science ID 000295841200075

• New Devices for Investigating Hair Cell Mechanical Properties WHAT FIRE IS IN MINE EARS: PROGRESS IN AUDITORY BIOMECHANICS Doll, J. C., Peng, A., Ricci, A., Pruitt, B. L. 2011; 1403

  View details for DOI 10.1063/1.3658054

  View details for Web of Science ID 000301945200003

• Electrically addressable, liquid release well array for a hand-held, scent-dispense system MICRO & NANO LETTERS Lamers, T., Chiang, P., Ruby, R., Pruitt, B. 2011; 6 (1): 37-38

  View details for DOI 10.1049/mnl.2010.0144

  View details for Web of Science ID 000285921300010

• Integrated strain array for cellular mechanobiology studies. Journal of micromechanics and microengineering : structures, devices, and systems Simmons, C. S., Sim, J. Y., Baechtold, P., Gonzalez, A., Chung, C., Borghi, N., Pruitt, B. L. 2011; 21 (5): 54016-54025

  Abstract

  We have developed an integrated strain array for cell culture enabling high-throughput mechano-transduction studies. Biocompatible cell culture chambers were integrated with an acrylic pneumatic compartment and microprocessor-based control system. Each element of the array consists of a deformable membrane supported by a cylindrical pillar within a well. For user-prescribed waveforms, the annular region of the deformable membrane is pulled into the well around the pillar under vacuum, causing the pillar-supported region with cultured cells to be stretched biaxially. The optically clear device and pillar-based mechanism of operation enables imaging on standard laboratory microscopes. Straightforward fabrication utilizes off-the-shelf components, soft lithography techniques in polydimethylsiloxane, and laser ablation of acrylic sheets. Proof of compatibility with basic biological assays and standard imaging equipment were accomplished by straining C2C12 skeletal myoblast cells on the device for 6 hours. At higher strains, cells and actin stress fibers realign with a circumferential preference.

  View details for PubMedID 21857773

• Design of piezoresistive versus piezoelectric contact mode scanning probes JOURNAL OF MICROMECHANICS AND MICROENGINEERING Doll, J. C., Pruitt, B. L. 2010; 20 (9)

  View details for DOI 10.1088/0960-1317/20/9/095023

  View details for Web of Science ID 000281398800023

• Strain array for cell culture: cyclic strain affects epithelial cell spreading Simmons, C., Sim, J. Y., Baechtold, P., Pruitt, B. FEDERATION AMER SOC EXP BIOL. 2010

  View details for Web of Science ID 000208675501606

• Aluminum nitride on titanium for CMOS compatible piezoelectric transducers JOURNAL OF MICROMECHANICS AND MICROENGINEERING Doll, J. C., Petzold, B. C., Ninan, B., Mullapudi, R., Pruitt, B. L. 2010; 20 (2)

  View details for DOI 10.1088/0960-1317/20/2/025008

  View details for Web of Science ID 000275331200010

• Role of surface roughness in hysteresis during adhesive elastic contact PHILOSOPHICAL MAGAZINE LETTERS Kesari, H., Doll, J. C., Pruitt, B. L., Cai, W., Lew, A. J. 2010; 90 (12): 891-902

  Abstract

  In experiments that involve contact with adhesion between two surfaces, as found in atomic force microscopy or nanoindentation, two distinct contact force (P) vs. indentation-depth (h) curves are often measured depending on whether the indenter moves towards or away from the sample. The origin of this hysteresis is not well understood and is often attributed to moisture, plasticity or viscoelasticity. Here we report experiments that show that hysteresis can exist in the absence of these effects, and that its magnitude depends on surface roughness. We develop a theoretical model in which the hysteresis appears as the result of a series of surface instabilities, in which the contact area grows or recedes by a finite amount. The model can be used to estimate material properties from contact experiments even when the measured P-h curves are not unique.

  View details for DOI 10.1080/09500839.2010.521204

  View details for Web of Science ID 000283319100005

  View details for PubMedID 21152108

• Force sensing optimization and applications book chapter in Advanced Materials and Technologies for Micro/Nano-Devices, Sensors and Actuators Doll, J., C., Park, S. -J., Rastegar, A., J., Harjee, N., Mallon Jr., J., R., Hill, G., Pruitt, B. Springer. 2010
• Microfabricated calibration tool for direct shear stiffness measurements with applications in cell mechanics Higgs, G., C., Simmons, C., S., Fried, A., F., Pruitt, B., L. 2010
• Parametric Analysis of Cyclic Strain Effects on Cell-cell Adhesions Sim, J., Simmons, C., Baechtold, P., Borghi, N., Pruitt, B., L. 2010
• Parametric analysis of cyclic strain effects on cell-cell adhesions Sim, J., Y., Simmons, C., Baechtold, P., Borghi, N., Pruitt, B., L. 2010
• Piezoresistive cantilevers optimized for kilohertz force sensing in aqueous solutions Doll, J., C., Petzold, B., C., Goodman, M., B., Pruitt, B., L. 2010
• Development of 3-dimesional Test Beds to Investigate Cell Matrix Interactions in vitro Chung, C., Sim, J.-Y., Heilshorn, S., Pruitt, B., L. 2010
• Micromechanical Environments for Imaging Mechanobiology Pruitt, B., L., Taylor, R., Simmmons, C., Sim, J., Y., Higgs, G., Chung, C. 2010
• Behavioral Thresholds for Force-sensation Determined by an Integrated Video Tracking and Force-clamp System Park, S. -J., Petzold, B., C., Fung, J., Pruitt, B., L., Goodman, M., B. 2010
• Piezoresistive cantilever performance, part II: optimization Journal of Microelectromechanical Systems Park, S. -J., Doll, J., C., Rastegar, A., J., Pruitt, B., L. 2010; 19 (1): 149 - 161
• Role of surface roughness in hysteresis during adhesive elastic contact Philosophical Magazine Letters Kesari, H., Doll, J., C., Pruitt, B., L., Cai, W., Lew, A., J. 2010
• The Contribution of Body Wall Muscles to C. Elegans Body Mechanics Determined Using Piezoresistive Microcantilevers Petzold, B., C., Park, S. -J., Ponce, P., Goodman, M., B., Pruitt, B., L. 2010
• Self-Assembling Single Cells Across Microposts: First Axial Force Measurements in Immature Cardiomyocytes Taylor, R., E., Kim, K., Pruitt, B., L. 2010
• Design of Piezoresistive vs. Piezoelectric Contact Mode Scanning Probes Journal of Micromechanics and Microengineering, Doll, J., C., Pruitt, B., L. 2010
• Microcantilever Force-Clamp and Optogenetics to Evaluate the Role of Body Mechanics in C. elegans Touch Sensation Park, S. -J., Petzold, B., Fung, J., Goodman, M., Pruitt, B., L. 2010
• Cardiomyocyte Suspension Bridges: First Measurements of Axial Force-Generation in Single Immature Heart Cells Taylor, R., E., Kim, K., Pruitt, B., L. 2010
• Aluminum Nitride on Titanium for CMOS Compatible Piezoelectric Transducers Journal of Micromechanics and Microengineering Doll, J., C., Petzold, B., C., Ninan, B., Mullapudi, R., Pruitt, B., L. 2010; 20: 25008
• Novel MEMS System for Calibrating Traction Force Substrates for Cell Culture Higgs, G., Simmons, C., Fried, A., Pruitt, B., L. 2010
• Piezoresistive cantilever performance, part I: analytical model for sensitivity Journal of Microelectromechanical Systems Park, S. -J., Doll, J., C., Pruitt, B., L. 2010; 19 (1): 137 - 148
• FORCE SENSING OPTIMIZATION AND APPLICATIONS ADVANCED MATERIALS AND TECHNOLOGIES FOR MICRO/NANO-DEVICES, SENSORS AND ACTUATORS Doll, J. C., Park, S., Rastegar, A. J., Harjee, N., Mallon, J. R., Hill, G. C., Barlian, A. A., Pruitt, B. L. 2010: 287-298

  View details for DOI 10.1007/978-90-481-3807-4_23

  View details for Web of Science ID 000280184600023

• COAXIAL TIP PIEZORESISTIVE SCANNING PROBES FOR HIGH-RESOLUTION ELECTRICAL IMAGING HARJEE, N., Garcia, A. G., Koenig, M., Doll, J. C., Goldhaber-Gordon, D., Pruitt, B. L. IEEE. 2010: 344-347

  View details for Web of Science ID 000278416400084

• Optimization with Process Limits and Application Requirements for Force Sensors 2010 IEEE SENSORS Park, S., Doll, J. C., Harjee, N., Pruitt, B. L. 2010: 1946-1949

  View details for Web of Science ID 000287982100427

• Coaxial Tip Piezoresistive Scanning Probes with Sub-Nanometer Vertical Displacement Resolution Harjee, N., Haemmerli, A., Goldhaber-Gordon, D., Pruitt, B. L. IEEE. 2010: 1962-1966

  View details for Web of Science ID 000287982100431

• Piezoresistive Cantilever Performance-Part I: Analytical Model for Sensitivity. Journal of microelectromechanical systems : a joint IEEE and ASME publication on microstructures, microactuators, microsensors, and microsystems Park, S. J., Doll, J. C., Pruitt, B. L. 2010; 19 (1): 137-148

  Abstract

  An accurate analytical model for the change in resistance of a piezoresistor is necessary for the design of silicon piezoresistive transducers. Ion implantation requires a high-temperature oxidation or annealing process to activate the dopant atoms, and this treatment results in a distorted dopant profile due to diffusion. Existing analytical models do not account for the concentration dependence of piezoresistance and are not accurate for nonuniform dopant profiles. We extend previous analytical work by introducing two nondimensional factors, namely, the efficiency and geometry factors. A practical benefit of this efficiency factor is that it separates the process parameters from the design parameters; thus, designers may address requirements for cantilever geometry and fabrication process independently. To facilitate the design process, we provide a lookup table for the efficiency factor over an extensive range of process conditions. The model was validated by comparing simulation results with the experimentally determined sensitivities of piezoresistive cantilevers. We performed 9200 TSUPREM4 simulations and fabricated 50 devices from six unique process flows; we systematically explored the design space relating process parameters and cantilever sensitivity. Our treatment focuses on piezoresistive cantilevers, but the analytical sensitivity model is extensible to other piezoresistive transducers such as membrane pressure sensors.

  View details for PubMedID 20336183

• Piezoresistive Cantilever Performance-Part II: Optimization. Journal of microelectromechanical systems : a joint IEEE and ASME publication on microstructures, microactuators, microsensors, and microsystems Park, S. J., Doll, J. C., Rastegar, A. J., Pruitt, B. L. 2010; 19 (1): 149-161

  Abstract

  Piezoresistive silicon cantilevers fabricated by ion implantation are frequently used for force, displacement, and chemical sensors due to their low cost and electronic readout. However, the design of piezoresistive cantilevers is not a straightforward problem due to coupling between the design parameters, constraints, process conditions, and performance. We systematically analyzed the effect of design and process parameters on force resolution and then developed an optimization approach to improve force resolution while satisfying various design constraints using simulation results. The combined simulation and optimization approach is extensible to other doping methods beyond ion implantation in principle. The optimization results were validated by fabricating cantilevers with the optimized conditions and characterizing their performance. The measurement results demonstrate that the analytical model accurately predicts force and displacement resolution, and sensitivity and noise tradeoff in optimal cantilever performance. We also performed a comparison between our optimization technique and existing models and demonstrated eight times improvement in force resolution over simplified models.

  View details for PubMedID 20333323

• Aluminum nitride on titanium for CMOS compatible piezoelectric transducers. Journal of micromechanics and microengineering : structures, devices, and systems Doll, J. C., Petzold, B. C., Ninan, B., Mullapudi, R., Pruitt, B. L. 2010; 20 (2): 25008

  Abstract

  Piezoelectric materials are widely used for microscale sensors and actuators but can pose material compatibility challenges. This paper reports a post-CMOS compatible fabrication process for piezoelectric sensors and actuators on silicon using only standard CMOS metals. The piezoelectric properties of aluminum nitride (AlN) deposited on titanium (Ti) by reactive sputtering are characterized and microcantilever actuators are demonstrated. The film texture of the polycrystalline Ti and AlN films is improved by removing the native oxide from the silicon substrate in situ and sequentially depositing the films under vacuum to provide a uniform growth surface. The piezoelectric properties for several AlN film thicknesses are measured using laser doppler vibrometry on unpatterned wafers and released cantilever beams. The film structure and properties are shown to vary with thickness, with values of d(33f), d(31) and d(33) of up to 2.9, -1.9 and 6.5 pm V(-1), respectively. These values are comparable with AlN deposited on a Pt metal electrode, but with the benefit of a fabrication process that uses only standard CMOS metals.

  View details for PubMedID 20333316

• Sidewall epitaxial piezoresistor process and characterisation for in-plane force sensing applications MICRO & NANO LETTERS Barlian, A. A., HARJEE, N., Pruitt, B. L. 2009; 4 (4): 204-209

  View details for DOI 10.1049/mnl.2009.0075

  View details for Web of Science ID 000273047200005

• Design optimization of piezoresistive cantilevers for force sensing in air and water JOURNAL OF APPLIED PHYSICS Doll, J. C., Park, S., Pruitt, B. L. 2009; 106 (6)

  View details for DOI 10.1063/1.3224965

  View details for Web of Science ID 000270378100128

• Modeling and characterization of electrostatic comb-drive actuators in conducting liquid media JOURNAL OF MICROMECHANICS AND MICROENGINEERING Mukundan, V., Ponce, P., Butterfield, H. E., Pruitt, B. L. 2009; 19 (6)

  View details for DOI 10.1088/0960-1317/19/6/065008

  View details for Web of Science ID 000266287200008

• SU-8 force sensing pillar arrays for biological measurements LAB ON A CHIP Doll, J. C., Harjee, N., Klejwa, N., Kwon, R., Coulthard, S. M., Petzold, B., Goodman, M. B., Pruitt, B. L. 2009; 9 (10): 1449-1454

  Abstract

  The generation and sensation of mechanical force plays a role in many dynamic biological processes, including touch sensation. This paper presents a two-axis micro strain gauge force sensor constructed from multiple layers of SU-8 and metal on quartz substrates. The sensor was designed to meet requirements for measuring tactile sensitivity and interaction forces exerted during locomotion by small organisms such as the nematode Caenorhabditis elegans. The device is transparent and compatible with light microscopes, allowing behavioral experiments to be combined with quantitative force measurements. For the first time, we have characterized the scale of interaction forces generated in wild-type C. elegans in probing and responding to their environment during locomotion. The device features sub-microN force resolution from 1 Hz to 1 kHz, >25 microN range, kHz acquisition rates and biocompatibility.

  View details for DOI 10.1039/b818622g

  View details for Web of Science ID 000268227400019

  View details for PubMedID 19417913

• MEMS Electrostatic Actuation in Conducting Biological Media JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Mukundan, V., Pruitt, B. L. 2009; 18 (2): 405-413

  Abstract

  We present design and experimental implementation of electrostatic comb-drive actuators in solutions of high conductivity relevant for biological cells. The actuators are operated in the frequency range 1-10 MHz in ionic and biological cell culture media, with ionic strengths up to 150 mMoles/L. Typical displacement is 3.5 ?m at an applied peak-to-peak signal of 5V. Two different actuation schemes are presented and tested for performance at high frequency. A differential drive design is demonstrated to overcome the attenuation due to losses in parasitic impedances. The frequency dependence of the electrostatic force has been characterized in media of different ionic strengths. Circuit models for the electric double layer phenomena are used to understand and predict the actuator behavior. The actuator is integrated into a planar force sensing system to measure the stiffness of cells cultured on suspended structures.

  View details for DOI 10.1109/JMEMS.2009.2013398

  View details for Web of Science ID 000265090300018

  View details for PubMedID 20161046

• Review: Semiconductor Piezoresistance for Microsystems PROCEEDINGS OF THE IEEE Barlian, A. A., Park, W., Mallon, J. R., Rastegar, A. J., Pruitt, B. L. 2009; 97 (3): 513-552

  Abstract

  Piezoresistive sensors are among the earliest micromachined silicon devices. The need for smaller, less expensive, higher performance sensors helped drive early micromachining technology, a precursor to microsystems or microelectromechanical systems (MEMS). The effect of stress on doped silicon and germanium has been known since the work of Smith at Bell Laboratories in 1954. Since then, researchers have extensively reported on microscale, piezoresistive strain gauges, pressure sensors, accelerometers, and cantilever force/displacement sensors, including many commercially successful devices. In this paper, we review the history of piezoresistance, its physics and related fabrication techniques. We also discuss electrical noise in piezoresistors, device examples and design considerations, and alternative materials. This paper provides a comprehensive overview of integrated piezoresistor technology with an introduction to the physics of piezoresistivity, process and material selection and design guidance useful to researchers and device engineers.

  View details for DOI 10.1109/JPROC.2009.2013612

  View details for Web of Science ID 000265092700006

  View details for PubMedID 20198118

• Design optimization of piezoresistive cantilevers for force sensing in air and water. Journal of applied physics Doll, J. C., Park, S. J., Pruitt, B. L. 2009; 106 (6): 64310

  Abstract

  Piezoresistive cantilevers fabricated from doped silicon or metal films are commonly used for force, topography, and chemical sensing at the micro- and macroscales. Proper design is required to optimize the achievable resolution by maximizing sensitivity while simultaneously minimizing the integrated noise over the bandwidth of interest. Existing analytical design methods are insufficient for modeling complex dopant profiles, design constraints, and nonlinear phenomena such as damping in fluid. Here we present an optimization method based on an analytical piezoresistive cantilever model. We use an existing iterative optimizer to minimimize a performance goal, such as minimum detectable force. The design tool is available as open source software. Optimal cantilever design and performance are found to strongly depend on the measurement bandwidth and the constraints applied. We discuss results for silicon piezoresistors fabricated by epitaxy and diffusion, but the method can be applied to any dopant profile or material which can be modeled in a similar fashion or extended to other microelectromechanical systems.

  View details for PubMedID 19865512

• A STRETCHABLE CELL CULTURE PLATFORM WITH EMBEDDED ELECTRODE ARRAY IEEE 22ND INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2009) Wei, P., Taylor, R., Ding, Z., Higgs, G., Norman, J. J., Pruitt, B. L., Ziaie, B. 2009: 407-410

  View details for Web of Science ID 000341431500102

• PIEZORESISTIVE CANTILEVER-BASED FORCE-CLAMP SYSTEM FOR THE STUDY OF MECHANOTRANSDUCTION IN C. ELEGANS IEEE 22ND INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2009) Park, S., Petzold, B., Goodman, M. B., Pruitt, B. L. 2009: 188-191

  View details for Web of Science ID 000341431500047

• A Stretchable Cell Culture Platform with Embedded Electrode Array Wei, P., Taylor, R., Ding, Z., Higgs, G., Norman, J., J., Pruitt, B., L. 2009
• MEMS Electrostatic Actuation in Conducting Biological Media Journal of Microelectromechanical Systems Mukundan, V., Pruitt, B., L. 2009; 18 (2): 405 - 413
• Modeling and Characterization of Electrostatic Comb-drive Actuators in Conducting Liquid Media Journal Micromechanics and Microengineering Mukundan, V., Ponce, P., Butterfield, H., E., Pruitt, B., L. 2009; 19: 65008
• Piezoresistive Cantilever Optimization and Applications invited paper, Materials Research Society Fall Meeting Doll, J., C., Park, S., J., Harjee, N., Rastegar, A., J., Mallon, J., R., Petzold, B., C., Pruitt, B. 2009
• Design optimization of piezoresistive cantilevers for force sensing in air and water Journal of Applied Physics Doll, J., C., Park, S. -J., Pruitt, B., L. 2009; 106 (6): 64310
• The Contribution of Body Wall Muscles to C. elegans Body Mechanics Determined Using Piezoresistive Microcantilevers Petzold, B., C., Park, S. -J., Ponce, P., Goodman, M., B., Pruitt, B., L. 2009
• Synchronized Mechanical and Electrical Stimulation of Primary Heart Cells with a Stretchable Microelectrode Array Taylor, R., Lue, S., J., Gumerlock, K., Fajardo, G., Higgs, G., Norman, J., J., Pruitt, B. 2009
• Strain Array for Cell Culture Bächtold, P., Simmons, C., S., Sim, J., Y., Haniff, S., Pruitt, B., L. 2009
• Semiconductor Piezoresistance for Microsystems Barlian, A., A., Park, W. -T., Mallon Jr., J., R., Rastegar, A., J., Pruitt, B., L. 2009
• Piezoresistive Cantilever-based Force clamp System for the Study of Mechanotransduction in C. elegans Park, S. -J., Petzold, B., Goodman, M., B., Pruitt, B., L. 2009
• On-chip Micromechanical Testing System for Studying Cell Mechanics Mukundan, V., Pruitt, B., L. 2009
• Measuring Thresholds for Touch Sensation in C. elegans Doll, J., C., Muntwyler, S., Beyeler, F., Geffeney, S., Goodman, M., B., Nelson, B., J., Pruitt, B. 2009
• A High d33 CMOS Compatible Process for Aluminum Nitride on Titanium Doll, J., C., Petzold, B., C., Ninan, B., Mullapudi, R., Pruitt, B., L. 2009
• Sidewall epitaxial piezoresistor process and characterization for in-plane force sensing applications Micro and Nano Letters Barlian, A., A., Harjee, N., Pruitt, B., L. 2009; 4 (4): 204-209
• High Frequency Force Sensing with Piezoresistive Cantilevers Doll, J., C., Petzold, B., C., Ghale, P., Goodman, M., B., Pruitt, B., L. 2009
• Nano and the Future of Endovascular Medicine Endovascular Today, supp. Taylor, R., Norman, J., J., Simmons, C., Abilez, O., J., Zarins, C., K., Pruitt, B., L. 2009: 27-31
• Modeling and Characterization of Electrostatic Comb-drive Actuators in Conducting Liquid Media. Journal of micromechanics and microengineering : structures, devices, and systems Mukundan, V., Ponce, P., Butterfield, H. E., Pruitt, B. L. 2009; 19 (6): 1-9

  Abstract

  Operation of electrostatic actuators in liquid media has various proposed applications, especially in biological environments. The devices are operated by modulating at a frequency higher than the relaxation rate of the ions in solution. We present circuit models based on electric double layer theories to obtain analytical expression for the frequency-dependent force response of electrostatic actuators in ionic media. The model has been compared with experimental measurements of actuation in media of conductivity spanning five orders of magnitude. Further, impedance spectroscopy is used to measure the values of the circuit models, which are compared with the experiments. These measurements also quantify the parasitic impedances in the devices. A conformal layer of Parylene-C is demonstrated as a passivation scheme for the electrodes in corrosive media. The heating effects due to parasitic impedances are also quantified by temperature measurements of devices in fluids.

  View details for PubMedID 20160927

• Artificial dirt: Microfluidic substrates for nematode neurobiology and behavior JOURNAL OF NEUROPHYSIOLOGY Lockery, S. R., Lawton, K. J., Doll, J. C., Faumont, S., COULTHARD, S. M., Thiele, T. R., Chronis, N., McCormick, K. E., Goodman, M. B., Pruitt, B. L. 2008; 99 (6): 3136-3143

  Abstract

  With a nervous system of only 302 neurons, the free-living nematode Caenorhabditis elegans is a powerful experimental organism for neurobiology. However, the laboratory substrate commonly used in C. elegans research, a planar agarose surface, fails to reflect the complexity of this organism's natural environment, complicates stimulus delivery, and is incompatible with high-resolution optophysiology experiments. Here we present a new class of microfluidic devices for C. elegans neurobiology and behavior: agarose-free, micron-scale chambers and channels that allow the animals to crawl as they would on agarose. One such device mimics a moist soil matrix and facilitates rapid delivery of fluid-borne stimuli. A second device consists of sinusoidal channels that can be used to regulate the waveform and trajectory of crawling worms. Both devices are thin and transparent, rendering them compatible with high-resolution microscope objectives for neuronal imaging and optical recording. Together, the new devices are likely to accelerate studies of the neuronal basis of behavior in C. elegans.

  View details for Web of Science ID 000256632600035

  View details for PubMedID 18337372

• Suspension of nanoparticles in SU-8: Processing and characterization of nanocomposite polymers Chiamori, H. C., Brown, J. W., Adhiprakasha, E. V., Hantsoo, E. T., Straalsund, J. B., Melosh, N. A., Pruitt, B. L. ELSEVIER SCI LTD. 2008: 228-236

  View details for DOI 10.1016/j.mejo.2007.05.012

  View details for Web of Science ID 000253562400010

• Low 1/f noise, full bridge, microcantilever with longitudinal and transverse piezoresistors APPLIED PHYSICS LETTERS Mallon, J. R., Rastegar, A. J., Barlian, A. A., Meyer, M. T., Fung, T. H., Pruitt, B. L. 2008; 92 (3)

  View details for DOI 10.1063/1.2825466

  View details for Web of Science ID 000252718600076

• Sidewall epitaxial piezoresistor process for in-plane sensing applications MEMS 2008: 21ST IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, TECHNICAL DIGEST Barlian, A. A., HARJEE, N., Mukundan, V., Fung, T. H., Park, S., Pruitt, B. L. 2008: 331-334

  View details for Web of Science ID 000253356900083

• Application of a modified quality function deployment method for MEMS INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION 2007, VOL 11 PT A AND PT B: MICRO AND NANO SYSTEMS Lamers, T. L., David, M., Goodson, K., Ishii, K., Pruitt, B. L. 2008: 159-168

  View details for Web of Science ID 000254834900023

• Vapor-venting, micromachined heat exchanger for electronics cooling PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION 2007, VOL 8, PTS A AND B David, M. P., Khurana, T., Hidrovo, C., Pruitt, B. L., Goodson, K. E. 2008: 951-960

  View details for Web of Science ID 000254515300105

• Ion Implanted Piezoresistive Cantilever Design and Performance Park, S. -J., Rastegar, A., J., Mallon, J., R. J., Barlian, A., A., Fung, T., H., Pruitt, B., L. 2008
• Microsystems for biomechanical measurements Pediatr Res Norman, J., J., Mukundan, V., Bernstein, D., Pruitt, B., L. 2008; 63 (5): 576-83
• Mechanical Strain Promotes Organization and Contractility of Human Embryonic-Derived Cardiomyocytes in Engineered Myocardial Tissue Blundo, J., Abilez, O., Cao, F., Zarins, C., Wu, J., Pruitt, B., L. 2008
• Molecular Imaging of Cardiac Constructs Derived from Human Embryonic Stem Cell Blundo, J., Abilez, O., Cao, F., Zarins, C., Wu, J., Pruitt, Beth. 2008
• Artificial dirt: Microfluidic substrates for nematode neurobiology and behavior J Neurophysiol Lockery, S., R., Lawton, K., J., Doll, J., C., Faumont, S., Coulthard, S., M., Thiele, T., R., Pruitt, B. 2008; 99 (6): 3136-43
• Suspension of nanoparticles in SU-8 and characterization of nanocomposite polymers Microelectronics Journal Chiamori, H., C., Brown, J., W., Adhiprakasha, E., V., Hantsoo, E., T., Straalsund, J., B., Melosh, N., A., Pruitt, B. 2008; 39: 228-236
• Modeling and Experimental Validation of Electrostatic Actuation in Aqueous Ionic Media Mukundan, V., Ponce, P., Butterfield, H., E., Pruitt, B., L. 2008
• Modeling and validation of electrostatic actuation in aqueous ionic media MEMS 2008: 21ST IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, TECHNICAL DIGEST Mukundan, V., Ponce, P., Butterfield, H. E., Pruitt, B. L. 2008: 467-470

  View details for Web of Science ID 000253356900117

• In vivo imaging and evaluation of different biomatrices for improvement of stem cell survival JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE Cao, F., Rafie, A. H., Abilez, O. J., Wang, H., Blundo, J. T., Pruitt, B., Zarins, C., Wu, J. C. 2007; 1 (6): 465-468

  Abstract

  Therapeutic effects from injection of stem cells are often hampered by acute donor cell death as well as migration away from damaged areas. This is likely due to the fact that injected cells do not have the physical and biochemical cues for ordered engrafment. Here we evaluate 3 common biomatrices (Matrigel, Collagen I, Purmatrix) that has the potential of providing suitable scaffolds needed to enhance stem cell survival. The longitudinal fate of transplanted stem cells was monitored by reporter imaging techniques.

  View details for DOI 10.1002/term.55

  View details for Web of Science ID 000256520300008

  View details for PubMedID 18163533

• Analysis of nematode mechanics by piezoresistive displacement clamp PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Park, S., Goodman, M. B., Pruitt, B. L. 2007; 104 (44): 17376-17381

  Abstract

  Studying animal mechanics is critical for understanding how signals in the neuromuscular system give rise to behavior and how force-sensing organs and sensory neurons work. Few techniques exist to provide forces and displacements appropriate for such studies. To address this technological gap, we developed a metrology using piezoresistive cantilevers as force-displacement sensors coupled to a feedback system to apply and maintain defined load profiles to micrometer-scale animals. We show that this system can deliver forces between 10(-8) and 10(-3) N across distances of up to 100 mum with a resolution of 12 nN between 0.1 Hz and 100 kHz. We use this new metrology to show that force-displacement curves of wild-type nematodes (Caenorhabditis elegans) are linear. Because nematodes have approximately cylindrical bodies, this finding demonstrates that nematode body mechanics can be modeled as a cylindrical shell under pressure. Little is known about the relative importance of hydrostatic pressure and shell mechanics, however. We show that dissipating pressure by cuticle puncture or decreasing it by hyperosmotic shock has only a modest effect on stiffness, whereas defects in the dpy-5 and lon-2 genes, which alter body shape and cuticle proteins, decrease and increase stiffness by 25% and 50%, respectively. This initial analysis of C. elegans body mechanics suggests that shell mechanics dominates stiffness and is a first step in understanding how body mechanics affect locomotion and force sensing.

  View details for DOI 10.1073/pnas.0702138104

  View details for Web of Science ID 000250638400028

  View details for PubMedID 17962419

• SU-8 MEMS Fabry-Perot pressure sensor SENSORS AND ACTUATORS A-PHYSICAL Hill, G. C., Melamud, R., Declercq, F. E., Davenport, A. A., Chan, I. H., Hartwell, P. G., Pruitt, B. L. 2007; 138 (1): 52-62

  View details for DOI 10.1016/j.sna.2007.04.047

  View details for Web of Science ID 000248296900008

• Biocompatible coatings for CMUTs in a harsh, aqueous environment JOURNAL OF MICROMECHANICS AND MICROENGINEERING Zhuang, X., Nikoozadeh, A., Beasley, M. A., Yaralioglu, G. G., Khuri-Yakub, B. T., Pruitt, B. L. 2007; 17 (5): 994-1001

  View details for DOI 10.1088/0960-1317/17/5/020

  View details for Web of Science ID 000246551600022

• Design and characterization of microfabricated piezoresistive floating element-based shear stress sensors Barlian, A. A., Park, S., Mukundan, V., Pruitt, B. L. ELSEVIER SCIENCE SA. 2007: 77-87

  View details for DOI 10.1016/j.sna.2006.04.035

  View details for Web of Science ID 000245066000010

• Transparent SU-8 three-axis micro strain gauge force sensing pillar arrays for biological applications TRANSDUCERS '07 & EUROSENSORS XXI, DIGEST OF TECHNICAL PAPERS, VOLS 1 AND 2 Klejwa, N., Harjee, N., Kwon, R., COULTHARD, S. M., Pruitt, B. L. 2007

  View details for Web of Science ID 000249603700562

• Characteristics of Parylene Coatings for CMUTs in a Harsh, Aqueous Environment Journal of Micromechanics and Microengineering Zhuang, X., Nikoozadeh, A., Beasley, M., A., G, Y., Khuri-Yakub, B., T., Pruitt, B., L. 2007; 17: 994-1001
• Biological measurements of C. Elegans touch sensitivity with microfabricated force sensors Doll, J., C., Harjee, N., Klejwa, N., Kwon, R., Coulthard, S., M., Pruitt, B., L. 2007
• Application of a modified quality function deployment method for MEMS Lamers, T., L., David, M., Goodson, K., Ishii, K., Pruitt, B., L. 2007
• Characterization of the DRIE Process for ETWI for Piezoresistive Inertial Sensors NNIN REU Research Accomplishments Suggs, M., Barlian, A., Harjee, N., Pruitt, B., L. 2007: 88-89
• In vivo imaging and evaluation of different biomatrices for improvement of stem cell survival J Tissue Eng Regen Med. Cao, F., Rafie, A., H. Sadrzadeh, Abilez, O., J., Wang, H., Blundo, J., T., Pruitt, B., L. 2007; 1 (6): 465-8
• A Vapor-venting, micromachined heat exchanger for electronics cooling David, M., P., Khurana, T., Hidrovo, C., Pruitt, B., L., Goodson, K., E. 2007
• Differential electrode design for electrostatic actuator in conducting media TRANSDUCERS '07 & EUROSENSORS XXI, DIGEST OF TECHNICAL PAPERS, VOLS 1 AND 2 Mukundan, V., Pruitt, B. 2007

  View details for Web of Science ID 000249603700281

• Biomems platform for electromechanical stimulation of cell culture PROCEEDING OF THE ASME SUMMER BIOENGINEERING CONFERENCE - 2007 Blundo, J., Chua, G., Abilez, O., Park, Y., Rastegar, A., Cao, F., Zairins, C., Wu, J., Pruitt, B. 2007: 63-64

  View details for Web of Science ID 000252105700032

• Pulsatile pressure system for cellular mechanical stimulation PROCEEDING OF THE ASME SUMMER BIOENGINEERING CONFERENCE - 2007 Taylor, R., Abilez, O., Cao, F., Wu, J., Xu, C., Zarins, C., Pruitt, B. 2007: 1009-1010

  View details for Web of Science ID 000252105700505

• Special Issue on Life Science Automation IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING Zhang, M. J., Felder, R. A., Kim, E. S., Nelson, B., Zurich, E., Pruitt, B. L., Zheng, Y. F., Meldrum, D. 2006; 3 (2): 137-140

  View details for DOI 10.1109/TASE.2006.871475

  View details for Web of Science ID 000236673600001

• Piezoresistive MEMS underwater shear stress sensors MEMS 2006: 19TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, TECHNICAL DIGEST Barlian, A. A., Narain, R., Li, J. T., Quance, C. E., Ho, A. C., Mukundan, V., Pruitt, B. L. 2006: 626-629

  View details for Web of Science ID 000236994500157

• Experimental Characterization of Frequency Dependent Electrostatic Actuator for Aqueous Media Mukundan, V., Pruitt, B., L. 2006
• A Biocompatible Coating for Capactive Micromachined Ultrasonic Transducers Beasley, M., A., Zhuang, X., Nikoozadeh, A., Khuri-Yakub, B., T., Pruitt, B., L. 2006
• Development of an Imaging System for On-Line Assessment of Human Embryonic Stem-Cell Derived Cardiomyocytes Abilez, O., J., Cao, F., Blundo, J., T., Wu, J., C., Pruitt, B., L., Zarins, C., K. 2006
• NSF/NASA-GSFC MEMS Education Workshop Outcomes Pruitt, B., L., Saif, M., T. A., Ghodssi, R., Turner, K., L., Judy, J., W., Schmidt, M., A. 2006
• Micro and Nano Scale Education at Stanford University Barlian, A., A., Kovacs, G., T. A., Howe, R., T., Pruitt, B., L. 2006
• Mechanical Properties of Wild Type and Mutant Caenorhabditis Elegans using a Closed Loop Piezoresistive Cantilever Indentation System Park, S. -J., Goodman, M., B., Pruitt, B., L. 2006
• Design of BioMEMS device for electromechanical stimulation of hESC Blundo, J., T., Abilez, O., J., Zarins, C., K., Wu, J., C., Pruitt, B., L. 2006
• Design of a Low Noise, Temperature Compensated, Piezoresistive Cantilever Mallon Jr., J., R., Barlian, A., A., Davenport, A., A., Lim, P., Pruitt, B., L. 2006
• A microfabricated direct methanol fuel cell with integrated electroosmotic pump MEMS 2006: 19TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS, TECHNICAL DIGEST Buie, C. R., BANIN, Y., Tang, C. Y., Santiago, J. G., Prinz, F. B., Pruitt, B. L. 2006: 938-941

  View details for Web of Science ID 000236994500235

• Development of an SU-8 Fabry Perot blood pressure sensor MEMS 2005 MIAMI: TECHNICAL DIGEST Melamud, R., Davenport, A. A., Hill, G. C., Chan, I. H., Declercq, F., Hartwell, P. G., Pruitt, B. L. 2005: 810-813

  View details for Web of Science ID 000228430000201

• Noise studies in implanted piezoresistors MICRO-ELECTRO-MECHANICAL SYSTEMS - 2005 Davenport, A. A., Pruitt, B., Lim, P. 2005; 7: 87-93

  View details for Web of Science ID 000243038100014

• Measurement of mechanical properties of Caenorhabditis elegans with a piezoresistive microcantilever system 2005 3RD IEEE/EMBS SPECIAL TOPIC CONFERENCE ON MICROTECHNOLOGY IN MEDICINE AND BIOLOGY Park, S. J., Goodman, M. B., Pruitt, B. L. 2005: 400-403

  View details for Web of Science ID 000234204800125

• Integration of K-12 Outreach with Design Projects in an Introductory Mechanical Engineering Course Bailey, T., L., Tung, A., T., Pruitt, B., L. 2005
• Noise Studies in Implanted Piezoresistors Davenport, A., Lim, P., Pruitt, B., L. 2005
• Characterization of modified polymers for high elongation strain sensing Hantsoo, E., T., Zhao, Y., Chial, V., Chan, K., Wu, K., Rose, K., A., Pruitt, B. 2005
• Measurement of mechanical properties of Caenorhabditis elegans with a piezoresistive microcantilever system Park, S., J., Goodman, M., B., Pruitt, B., L. 2005
• Design, fabrication, and characterization of piezoresistive MEMS shear stress sensors MICRO-ELECTRO-MECHANICAL SYSTEMS - 2005 Barlian, A. A., Park, S., Mukundan, V., Pruitt, B. L. 2005; 7: 531-536

  View details for Web of Science ID 000243038100083

• Strain transduction in conductor-modified polymers MICRO- AND NANOSYSTEMS-MATERIALS AND DEVICES Hantsoo, E. T., Chial, V. B., Zhao, Y., Chan, K. C., Rose, K. A., Wu, K. S., Pruitt, B. L. 2005; 872: 49-54

  View details for Web of Science ID 000234461000008

• Measurement system for low force and small displacement contacts JOURNAL OF MICROELECTROMECHANICAL SYSTEMS Pruitt, B. L., Park, W. T., Kenny, T. W. 2004; 13 (2): 220-229

  View details for Web of Science ID 000220759300008

• presentation: Piezoresistive MEMS Underwater Shear Stress Sensor Barlian, A., A., Badi, M., H., Mukundan, V., Park, S. -J., Davenport, A., A., Pruitt, B., L. 2004
• Fundamental noise in MEMS force sensors NOISE AND INFORMATION IN NANOELECTRONICS, SENSORS, AND STANDARDS II Kenny, T. W., Liang, Y. C., Pruitt, B. L., Harley, J. A. 2004; 5472: 143-151

  View details for DOI 10.1117/12.549814

  View details for Web of Science ID 000223225600017

• Piezoresistive cantilevers and measurement system for characterizing low force electrical contacts SENSORS AND ACTUATORS A-PHYSICAL Pruitt, B. L., Kenny, T. W. 2003; 104 (1): 68-77

  View details for DOI 10.1016/S0924-4247(02)00485-5

  View details for Web of Science ID 000181236100011

• Piezoresistive Cantilevers and Measurement System for Characterizing Low Force Electrical Contacts Sens. Actuators A, Phys., Sensors and Actuators A (Physical) Pruitt, B., L., Kenny, T., W. 2003; 104 (1): 68 - 77
• Low Force Contact Resistance Measurements of Thin Film Gold Using Micromachined Piezoresistive Cantilevers Pruitt, B., L., Park, W. -T., Choi, D. -H., Nix, W., D., Kenny, T., W. 2001
• Low force electrical contact measurements using piezoresistive MEMS cantilevers to characterize thin-film metallization TRANSDUCERS '01: EUROSENSORS XV, DIGEST OF TECHNICAL PAPERS, VOLS 1 AND 2 Pruitt, B., Choi, D. H., Florando, J., Martens, R., Wenzel, S., Reynolds, C., Nix, W., Kenny, T. 2001: 1032-1035

  View details for Web of Science ID 000172547800237

• Low force electrical contact measurements using piezoresistive cantilevers to characterize thin-film metallization Pruitt, B., L., Choi, D., H., Florando, J., Martens, R., Wenzel, S., Reynolds, C. 2001
• A Three-Axis Micromachined Force Sensor for Studying Cockroach Biomechanics Bartsch, M., Partridge, A., Pruitt, B., L., Full, R., Kenny, T. 2000
• Design of piezoresistive cantilevers for low force electrical contact measurements Pruitt, B., L., Partridge, A., Bartsch, M., Liang, Y., Kenny, T., W., Wenzel, S. 2000
• Layered Manufacturing with Embedded Components: Process Planning Considerations Cham, J., G., Pruitt, B., L., Cutkosky, M., R., Binnard, M., Weiss, L., E., Neplotnik, G. 1999
• Velocity Measurements in the Flow Around an Rotating End Mill Flack, K., Pruitt, B., L., Callari, M. 1998
• Monitoring End Mill Contact Using Acoustic Emission Pruitt, B., L., Dornfeld, D., A. 1996
• IMPROVEMENT OF SYMPTOMS IN TOURETTE SYNDROME BY PIQUINDONE, A NOVEL DOPAMINE-2 RECEPTOR ANTAGONIST INTERNATIONAL CLINICAL PSYCHOPHARMACOLOGY UHR, S. B., Pruitt, B., Berger, P. A., Stahl, S. M. 1986; 1 (3): 216-220

  Abstract

  We have hypothesized that symptoms of Tourette Syndrome (TS) may represent D2 (dopamine-2) receptor hyperactivity. We treated 4 TS patients with piquindone, a novel D2 receptor antagonist designed via a 3-dimensional model of dopamine receptors. All 4 patients experienced a clinically obvious reduction of tics. Sedation that decreased over time was the only adverse effect. Haloperidol, the current treatment of choice of TS, is limited primarily by its extrapyramidal side-effects. However, piquindone produced therapeutic effects without disabling side-effects. Motor tics responded at lower doses than vocal tics. All patients expressed a strong subjective preference for piquindone over haloperidol. Our results suggest that therapeutic efficacy of a D2 receptor antagonist in TS can be achieved without production of disabling extrapyramidal-side effects. These results also support the proposal that TS may be mediated by hyperactive D2 receptors.

  View details for Web of Science ID A1986F845600004

  View details for PubMedID 3549873

• CASE-REPORT OF 4 PATIENTS WITH TOURETTE SYNDROME TREATED WITH PIQUINDONE, A D2 RECEPTOR ANTAGONIST JOURNAL OF CLINICAL PSYCHOPHARMACOLOGY UHR, S. B., Pruitt, B., Berger, P. A., Stahl, S. M. 1986; 6 (2): 128-130

  View details for Web of Science ID A1986A703800022

  View details for PubMedID 2871057

• TREATMENT OF TOURETTES SYNDROME WITH RO22-1319, A D-2-RECEPTOR ANTAGONIST NEW ENGLAND JOURNAL OF MEDICINE UHR, S. B., Berger, P. A., Pruitt, B., Stahl, S. M. 1984; 311 (15): 989-989

  View details for Web of Science ID A1984TM02000020

  View details for PubMedID 6147753