Surface micromachined capacitive ultrasonic transducers

TLDR

Surface microfabricated ultrasonic transducers are a novel technology whose current state is reported. The study presents experiments demonstrating both air and water transmission of these transducers. A theoretical model is proposed that aligns closely with observed transducer behavior. The transducers achieve air‑coupled longitudinal wave transmission through aluminum with a 110 dB dynamic range at 2.3 MHz, deliver 60 dB SNR at 3 MHz across 1–20 MHz in water, and the model shows they are a compelling alternative to piezoelectric transducers.

Abstract

The current state of novel technology, surface microfabricated ultrasonic transducers, is reported. Experiments demonstrating both air and water transmission are presented. Air-coupled longitudinal wave transmission through aluminum is demonstrated, implying a 110 dB dynamic range for transducers at 2.3 MHz in air. Water transmission experiments from 1 to 20 MHz are performed, with a measured 60 dB SNR at 3 MHz. A theoretical model is proposed that agrees well with observed transducer behavior. Most significantly, the model is used to demonstrate that microfabricated ultrasonic transducers constitute an attractive alternative to piezoelectric transducers in many applications.