A compact impact sensor utilizing elastic piezoelectric films and wide-bandwidth amplifier

This paper presents a new type of impact sensors which employ highly-sensitive piezoelectric polydimethylsiloxane (PDMS) films and voltage amplifiers with low cut-off frequency (f_L) and wide dynamic range. The PDMS films feature cellular structures with controllable, surface-charged micro-voids, which function as dipoles and respond promptly to electromechanical stimulation. To sense the open-loop voltage generated through force impulses, the integrated amplifier employs a 10-GΩ biasing resistor and a DC servo amplifier to realize a 3-dB-bandwidth ranging from 0.35 Hz to 7.5 MHz, and to eliminate its voltage offset as well. In the prototype demonstration, the proposed impact sensors show a sensitivity up to 0.236 V/N and a capacity to track impulses with frequency down to 0.4 Hz. As such, the new impact sensors could potentially accomplish great flexibility, high sensitivity and wide dynamic range, which are desired for a variety of biomechanics and ergonomics applications.