Additive manufacturing (AM) capacitive acoustic and ultrasonic transducers using a commercial direct light processing (DLP) printer

In recent years, there has been increasing interest in using additive manufacturing (3D printing) technology to fabricate sensors and actuators due to rapid prototyping, low-cost manufacturing processes, customized features and the ability to create complex geometries at micrometre scale. State of the art additive manufactured acoustic and ultrasonic transducers show limitations in miniaturization, repeatability (defects) and sensitivity. This new work encompasses the development of a capacitive acoustic and ultrasonic transducer, including its fabrication process using a commercial digital light processing printer and output signal characterization with a custom-made amplification circuit. A set of capacitive acoustic and ultrasonic transducers was fabricated and tested using different diaphragm diameters from 1.8 -2.2mm, for comparison, with central operating frequency between 19 -54 kHz, respectively. This capacitive transducer design has a receiving sensitivity of up to 0.4 mV/Pα at its resonant frequency, and a comparison with a commercial reference microphone is provided.