Normally closed plunger-membrane microvalve self-actuated electrically using a shape memory alloy wire
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Various microfluidic architectures designed for in vivo and point-of-care diagnostic applications require larger channels, autonomous actuation, and portability. In this paper, we present a normally closed microvalve design capable of fully autonomous actuation for wide diameter microchannels (tens to hundreds of µm). We fabricated the multilayer plunger-membrane valve architecture using the silicone elastomer, poly-dimethylsiloxane (PDMS) and optimized it to reduce the force required to open the valve. A 50-µm Nitinol (NiTi) shape memory alloy wire is incorporated into the device and can operate the valve when actuated with 100-mA current delivered from a 3-V supply. We characterized the valve for its actuation kinetics using an electrochemical assay and tested its reliability at 1.5-s cycle duration for 1 million cycles during which we observed no operational degradation.
KeywordsValve Point-of-care Nitinol Self-actuated PDMS
We thank Kevin King, Annie Mao, and Scott Sterrett for previous microfluidics work toward safe DC stimulator design. We also acknowledge the funding sources that made this work possible: MedEl Corporate Grant: FK2350 and NIH R01NS092726.