Compliance-Based Latchable Microfluidic Actuators Using a Paraffin Wax

This paper presents a novel phase-change actuator that can be potentially used for microvalves in lab-on-a-chip systems where minimal energy consumption is required. The actuator exploits a low melting-point paraffin wax, whose solid-liquid phase changes allow the closing and opening of fluid flow through deformable microchannels. Flow switching is initiated by melting of paraffin using integrated heaters, with an additional pneumatic pressure used for flow switching from open to closed state. After paraffin solidifies the switched flow state is subsequently maintained without further energy consumption. The actuator can be fabricated from PDMS through the multilayer soft lithography technique. Experiments demonstrate that the actuators can switch the flow state within 4-8 seconds, which can be further sped up with improved heater designs.