Fast Response Paraffin Compound Phase Change Microactuator

S. Movahedian, J. Martinez-Quijada, T. Thundat
University of Alberta, CA

Keywords: phase change, microactuator

Summary:

Control of the fluid flow in microfluidic chemical and biological devices is critical for their efficient operation. Therefore, the development of fast responding microvalves, which can be integrated into a microfluidic platform, is very important. We are presenting a rapid response PC microactuator for use in microvalve applications in lab-on-a-chip (LOC) systems. It is comprised of a reservoir sealed by a flexible membrane and filled with a novel PC material consisting of paraffin loaded with high thermal conductivity particles. The device is made of two pre-patterned photopolymer (SU-8) layers joined by a lamination process on a glass substrate. The actuator can deliver a large range of motion (>20µm on a 1 mm radius, ~15 µm thick membrane) with high pressure (1.5 kPa) and is at least five times faster than similar devices. This faster response is due to the enhanced heat transfer produced by the particles, which macroscopically manifests as a 30% reduction of the melting point of the paraffin. The membrane isolates the PC compound from the fluid, preventing contamination.