Novel methods for microfluidic mixing and control

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Virginia Tech


Microfluidics is a constantly evolving area of research. The implementation of new technologies and fabrication processes offers novel methodologies to solve existing problems. There are currently a large number of established techniques to address issues associated with microscale mixing and valving. We present mixing and valving techniques that utilize simplified and inexpensive techniques.

The first technique addresses issues associated with microscale mixing. Exercising control over animal locomotion is well known in the macro world but in the micro-scale world, control requires more sophistication. We present a method to artificially magnetize microorganisms and use external permanent magnets to control their motion in a microfluidic device. This effectively tethers the microorganisms to a location in the channel and controls where mixing occurs. We use the bulk and ciliary motion of the microswimmers to generate shear flows, thus enhancing cross-stream mixing by supplementing diffusion. The device is similar to an active mixer but requires no external power sources or artificial actuators.

The second technique examines a methodology involving the integration of electroactive polymers into microfluidic devices. Under the influence of high applied voltages, electroactive polymers with fixed boundary conditions undergo out-of-plane deformation. We use this finding to create a valve capable blocking flow in microchannels. Electrolytic fluid solutions are used as electrodes to carry the voltage signal to the polymer surface. Currently we have demonstrated this methodology as a proof of concept, but aim to optimize our system to develop a robust microvalve technology.



microswimmers, microfluidics, mixing, valving