A bioMEMS sensor platform based on a cantilever with a precisely patterned environmentally sensitive hydrogel

A novel photolithography process was utilized to precisely align and pattern environmentally sensitive hydrogels onto silicon microcantilevers, after microcantilevers were fabricated and released. By patterning environmentally sensitive hydrogels onto silicon microcantilevers, an ultrasensitive pH microsensor was prepared for MEMS and bioMEMS applications. Specifically, a crosslinked poly(methacrylic acid) network containing significant amounts of poly(ethylene glycol) dimethacrylate was studied. This hydrogel exhibits a swelling dependence on pH. Hydrogels were patterned onto the silicon microcantilevers utilizing a mask aligner to allow for precise positioning. Via modification of the silicon surface with γ-methacryloxypropyl trimethoxysilane, covalent adhesion was gained between the polymer and the silicon surface. The micropatterned hydrogels were analyzed using optical microscopy and profilometry. The bending response of patterned cantilevers with a change in environmental pH was observed, providing proof-of-concept for a MEMS/bioMEMS sensor based on microcantilevers patterned with environmentally sensitive hydrogels.