Researchers from Penn State's Department of Engineering Science and Mechanics have published ACS Applied Materials & interfaces paper "Strain-Tunable Microfluidic Devices with Crack and Wrinkle Microvalves for Microsphere Screening and Fluidic Logic Gates" highlighting a simple, low-cost, efficient way to fabricate strain-tunable elastomeric micropatterns as microvalves in a microfluidic device.
“The crack microvalves are closed before stretching but open as the tensile strain increases, whereas the wrinkle microvalves exhibit the opposite trend. The microfluidic device with crack and wrinkle microvalves is demonstrated for microparticle screening and fluidic logic operation in a programmable manner. The applied tensile strain changes the width and depth of the crack microvalves to control the selective transport of microparticles of different sizes. When the crack and wrinkle microvalves are integrated into the single microfluidic device, the fluid can be modulated to flow through the microvalves in a manner that represents the operation of the OR or AND logic gates. These controllable valves to adjust the reaction time and volume represent a viable path toward large-scale integration for potential applications in multiliquid, multistep sample preparation, and reagent processing. The programmable microfluidic system demonstrated in this study opens up additional opportunities to complement the prior reports in applications ranging from biomedicine and organ-on-chips to drug delivery and reagent mixing. However, PDMS is prone to swelling in many organic solvents. Although the application of the device with PDMS is limited (aqueous solutions), the concept from this study can be applied to the other soft materials that are stable in the target organic solvent.”
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