An individual addressable and latchable actuator array for microfluidic systems

Microfluidic systems and applications are becoming more and more complex and therefore require a lot of individually addressable actuators and valves to guide the fluids inside the systems. In this paper, we present an actuator array based on a latchable phase change actuator, i.e. the solid/liquid phase change of the actuator medium is used to stabilize the two states of the actuator. The design of the actuator allows the individual control of a high number of actuators with only two external pressure lines. This is in contrast to conventional pressure-actuated membrane valves manufactured in soft elastomers such as PDMS (polydimethylsiloxane) which require increasing numbers of external pressure lines for a higher number of valves. First, we describe the general working principle of the actuator. The scalability of the actuator concept as well as the individual addressing is then demonstrated by means of two exemplary set-ups with four and twelve actuators. With the latter, we also show the suitability as a microvalve. We further characterized and optimized the response times of the actuator with respect to the heating power, the choice of the phase change medium as well as the volume of the actuator material used. We achieved switching times between the two stable states of the actuators in the range of 10 s.