We present an electrostatic actuator fabricated on a flexible polyethylene naphthalate (PEN) substrate, which emits acoustic waves at ultrasonic frequencies. The MEMS actuator has a suspended parylene diaphragm which consists of 2-6 mm diameter and 6 μm gap between the diaphragm and substrate. Driving circuitry consists of voltage controlled oscillator (VCO) and output buffer chain, and was fabricated by Arizona State University's Flexible Display Center-IC process. The fabricated actuator emits ultrasonic waves at 25 kHz, and acoustic sound pressure of 27 dB SPL (sound pressure level) driven by the hydrogenated amorphous silicon (a-Si:H) circuitry.
Kim, S, X Zhang, R Daugherty, E Lee, G Kunnen, DR Allee, E Forsythe, J Chae
Sensors and Actuators A: Physical