Low-frequency amplifiers for PVDF film sensors

This paper proposes instrumental ion amplifiers for use with large area Polyvinylidine Diflouride (PVDF) sensors designed to detect rodent motion. The sensor behaves as a pressure-to-voltage converter in series with a parasitic capacitance. Motion signals critical for classifying rodent behavior range from 0.5 Hz to 20 Hz. Amplification on the order of 20 dB is required for the pass-band before digitization. Amplifier A is presently used in art experimental system. This amplifier has slow response time with noticeable drift. Amplifier B is designed to overcome these obstacles. It is more complex but reduces the drift and noise floor, while decreasing the response time. Performance is evaluated with metrics based on low-frequency drift and noise-floor power computed over a 19-hour period and with recovery time from saturation. The comparison shows amplifier B with a faster response and lower drift than amplifier A.