Normally closed plunger-membrane microvalve self-actuated electrically using a shape memory alloy wire

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 mu m). 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-mu m 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.