(130c) Wireless Measurement of Enzymatic Degradation Kinetics with a Resonant Antenna Biosensor

This work focuses on the development of a chipless radio frequency biosensor that can be embedded both in or on materials for wireless monitoring of biologic activity. The coil antennas are patterned on copper coated polyimide substrates and etched with a solution containing hydrogen peroxide and hydrochloric acid. The antenna’s initial resonant frequency is designed by the coil length and spiral’s pitch and is tuned for the 1-100MHz range (for better penetration through soil, water, and tissue). The resonant frequency is measured at a distance by a two-loop coil attached to a vector network analyzer monitoring the S21 parameter. The resonant frequency shifts with any change in capacitance between the antenna coil caused by variation in dielectric permittivity of the medium on top of the antenna. In this research effort, we apply this sensor platform to study the activity of protease degradation of gelatin materials. The wireless sensors allow us to measure the effect of gelatin content, plasticizer weight percentage, and enzyme concentration on the overall degradation profile of the gelatin film in a simple, multiplexed experiment. We correlate these results to the mechanical properties of the gelatin films. We also discuss extensions of these sensors in other applications where measuring biologic activity in contexts where lack of optical and electrical connection impede existing tools, such as monitoring the contents of a disposable bioreactor.