Testing Your Device
So now you have designed your microfluidic circuit, received your chip and are ready to start testing your microfluidic device!
Your test set-up will of course be specific to your application, but there are a few techniques outlined here which you may want to use to get started or which you may find useful to integrate into your particular testing set-up.
1) Testing Using Manually Controlled Syringes(parts list included)
2) Testing Using Manually Controlled Manifolds (parts list included)
3) Testing Using Pre-made Controller Box(purchasing info included)
4) Building Your Own Valve Controller (parts list and assembly instructions included)
For most designs, valve functionality can be tested by first filling the control lines with DI water. Due to the gas permeable properties of PDMS, the dead-end control channels will be depleted of air (air will diffuse through the PDMS) if you continue to push liquid into the control channels resulting in a bubble-free liquid filled channel. Once the channels are filled, if you apply further pressure you will be able to close the on-chip valves. The opening and closing can be monitored under a microscope. The figure below shows a typical open and closed valve. Anywhere between 0-30psi may be required to close the on-chip valves.
Top photo shows a control line (horizontal) and a flow line (vertical) crossing at 90° and the valve is open. Bottom photo shows the valve closed when pressure is applied to the control line.
