Department of Applied Physics

Description

Nanoscience and Quantum Engineering

Time-Resolved Tapping Force Near-Field Microscopy - The interaction forces between the tip and sample in Atomic Force Microscopes (AFMs) operated in tapping mode contain information about the topography as well as the chemical and mechanical properties of the sample. Up to now, it has proven difficult to measure these forces with sufficient accuracy to obtain information other than the topography of the sample. We have designed, fabricated, and demonstrated AFM cantilevers with superior high-frequency response to overcome this measurement problem, and we have shown that high-resolution images based on chemical and mechanical contrast mechanisms can be generated. We are now developing this tool, which we call Time-Resolved Tapping Force Near-field Microscopy (TTFN) for the study of biomolecular interactions.

Biophysics

In-Vivo Confocal Microscopy - Confocal microscopy is a promising technique for subsurface in-vivo imaging and early detection of anomalies associated with cancer and other diseases. In collaboration with the research groups of Professors Christopher Contag and Gordon Kino, we are developing MEMS scanners and microoptics for endoscopic implementations of dual-axes confocal microscopes, specifically designed for diagnosis of malignacy in the GI tract and the brain, as well as for in-vivo observations on molecular functions.

Courses Taught

• Micro and Nano Optical Device Design

Selected Publications

• Cantilevers with integrated sensor for time-resolved force measurement in tapping-mode atomic force microscopy
• Controlling uncoupled resonances in photonic crystals through breaking the mirror symmetry
• A Large-Area High-Reflectivity Broadband Monolithic Single-Crystal-Silicon Photonic Crystal MEMS Scanner With Low Dependence on Incident Angle and Polarization
• siRNA silencing of keratinocyte-specific GFP expression in a transgenic mouse skin model
• 3-D Near-Infrared Imaging Using a MEMS-Based Miniature Dual-Axis Confocal Microscope
• Asymmetrical Spectral Response in Fiber Fabry–Pérot Interferometers
• Two-dimensional photonic crystals fabricated in monolithic single-crystal silicon
• Micromirror-scanned dual-Axis confocal microscope utilizing a gradient-index relay lensfor image guidance during brain surgery
• Assessing delivery and quantifying efficacy of small interfering ribonucleic acid therapeutics in the skin using a dual-axis confocal microscope
• Multifunctional Tunable Optical Filter Using MEMS Spatial Light Modulator