3D-Printed Air-Coupled Ultrasonic Transducer Based on Conductive Filament

3D-printing holds the potential to revolutionize transducer manufacturing in terms of low-cost and customizability thanks its design flexibility. The transducer can be individually designed to specific applications concerning shape and by tuning performance properties. In this study, we investigate using conductive filament as an electrode in a 3D-printed, air-coupled, capacitive, ultrasonic transducer. The transducer is based on biocompatible and biodegradable polylactide (PLA). We investigate the transducers output sound pressure level (SPL) in an anechoeic chamber compared to a transducer of the same design with an evaporated aluminum electrode at a maximum actuation of 300 VDC and 250 VDC. The transducer shows a maximum SPL of 95.75 dB, slightly exceeding the SPL of the reference transducer at 93.82 dB, proving the functionality of the printed electrode. Additionally, we polarize the transducer with contact charging to evaluate the materials suitability as a ferroelectret without using a DC-bias voltage and track the SPL over a period of 72 hours. However, the sound pressure rapidly dropped, leaving practically no effect of the initial polarizing after 72 hours. Therefore, the used filament is not suitable to form a ferroelectret. The advances presented in this work mark another step toward creating a fully printable ultrasonic transducer increasing the accessibility and simplification of transducer manufacturing and show the suitability of conductive filament to be used as an electrode in an ultrasonic transducer.