(713b) Microcantilever Sensors Utilizing Biodegradable, pH-Responsive Hydrogel

Environmentally-responsive hydrogels are well suited for in vivo microsensing applications due to their biocompatibility and ability to be micropatterned via photolithography. Microcantilever transducers offer many advantages including their small size, high sensitivity, and versatility when utilized as arrays. Together, these generate a novel microsensor which utilizes a biodegradable, pH-responsive hydrogel network as its sensing element.

Biodegradable, pH-responsive hydrogel networks composed of poly(methacrylic acid) crosslinked with polycaprolactone diacrylate were synthesized via UV free radical polymerization. These materials were photopolymerized atop silicon microcantilever beams to generate novel microsensors. The hydrogel adhered to the silicon via a self assembled monolayer (SAM) of 3-methacryloxypropyltrimethoxysilane. Both the sensitivity and range of these sensors was varied by altering the percentage crosslinking of the hydrogel. The sensor composed of poly(methacrylic acid) crosslinked with 20 mole percent polycaprolactone diacrylate demonstrated a maximum sensitivity of 1 nm / 1 e-4 pH unit. The sensor performance was optimized by experimenting with microcantilevers of varying geometry and different force constants. This work shows promise towards the development of completely biodegradable sensors which could perform in vivo biosensing.