Polyurethane rubber as a MEMS material: characterization and demonstration of an all-polymer two-axis artificial hair cell flow sensor

Characterization and utilization of a two-part room temperature curing polyurethane elastomer as a MEMS material is presented. Chemical resistance, thermal degradation, elastic modulus, and adhesion are tested and compared to the performance of polydimethylsiloxane (PDMS). Polyurethane elastomer is found to exhibit excellent elastic and adhesion performance, with reduced solvent resistance when compared to PDMS. A two-axis artificial hair cell (AHC) is fabricated with carbon impregnated polyurethane force sensitive resistors (FSRs) at the base of a vertical polyurethane cantilever hair. The FSRs transduce the motion of the cilium into a change in resistance via a half-bridge. Device sensitivity is found to be 245 ppm resistance change per micron (ppm/um) of tip deflection.