Dual-Backplate CMUTs With Wide Bandwidth and Low Driving Voltage for Airborne Applications

In this work, novel airborne capacitive micromachined ultrasonic transducers (CMUTs) based on a dual-backplate (DBP) technology are presented. In contrast to conventional CMUTs, these transducers use a three-electrode-based capacitive system, where the membrane is placed between two highly-perforated counter electrodes, enabling enlarged displacement amplitudes in electrostatic actuation and wide and tunable bandwidth (BW) due to a ventilated air cavity. Fabricated DBP-CMUT prototypes therefore show exceptionally high receive and transmit sensitivities of -34.5 dB(V/Pa) and 259 nm/V, respectively, in their 84-kHz resonance. The viscous dissipation introduced by ventilating the cavity results in a wide factional BW (FBW) of 29%. Applicability of the developed CMUT for airborne ranging is demonstrated in pulse-echo-based ranging measurements, where the distance of a sound-reflecting metal plate can be clearly detected by a single CMUT operated in a transceiver mode.

Automated summary

This work presents novel airborne capacitive micromachined ultrasonic transducers (CMUTs) based on dual-backplate (DBP) technology. These transducers, unlike conventional CMUTs, employ a three-electrode capacitive system, enabling larger displacement amplitudes and wide adjustable bandwidth. The fabricated DBP-CMUT prototypes demonstrate high receive and transmit sensitivities, making them suitable for airborne ranging applications.