J. Zachary Hilt

Ultrasensitive Biomems Sensors Based on Microcantilevers Patterned with Environmentally Responsive Hydrogels

An innovative platform was developed for ultrasensitive microsensors based on microcantilevers patterned with crosslinked copolymeric hydrogels. A novel UV free-radical photolithography process was utilized to precisely align and pattern environmentally responsive hydrogels onto silicon microcantilevers, after microcantilevers were fabricated and released. Specifically, a crosslinked poly(methacrylic acid) network containing high amounts of poly(ethylene glycol) dimethacrylate was prepared and investigated. Hydrogels were patterned onto the silicon microcantilevers utilizing a mask aligner to allow for precise positioning. The silicon surface was modified with γ-methacryloxypropyl trimethoxysilane to gain covalent adhesion between the polymer and the silicon. The hydrogels sensed and responded to changes in environmental pH resulting in a variation in surface stress that deflected the microcantilever. The bending response of patterned cantilevers with a change in environmental pH was observed, showing the possibility to construct MEMS/BioMEMS sensors based on microcantilevers patterned with environmentally responsive hydrogels. An extraordinary maximum sensitivity of 1 nm/5×10−5ΔpH was observed, demonstrating the ultrasensitivity of this microsensor platform.

Intelligent Polymeric Networks in Biomolecular Sensing

Since the development of the first biological sensor over 40 years ago [1], the biosensor field has continuously evolved. Today, biosensors are applied in a wide range of uses, including environmental analysis, medical diagnostics, bioprocess monitoring, and biowarfare agent detection. The success of the biosensor is dependent on the ability to rapidly, sensitively, and selectively recognize various biomolecules, with relative importance dependent on the application.