A Flexible Piezoelectric Ultrasonic Patch With Low Operating Voltage and Enhanced Safety for Bubble Cavitation

ABSTRACT The ultrasonic cavitation effect plays a critical role in non‐invasive medical treatment. To develop a flexible ultrasonic cavitation patch, it is necessary to enhance the emission intensity of the transducer to reach the threshold sound pressure at low operating voltages, while simultaneously minimizing potential risks to surrounding tissues. This paper presents a piezoelectric ultrasonic micro‐patch with low operating voltage and high safety. The device is fabricated using microfabrication techniques to obtain thin piezoelectric ceramics, which are then embedded in an elastic base layer to ensure optimal adhesion. A ring‐island structure is further designed to integrate both ultrasonic emission and reception functions within a single patch. Sound field simulation and experimental results indicate that, under a driving voltage of 25 Vpp, the emitted ultrasonic intensity reaches 90 kPa, enabling the observation of bubble generation and oscillation in liquids. The mechanical index is only 0.11. To enhance safety, an ultrasonic switch circuit was designed to ensure the temperature remains below 38°C and the spatial‐peak temporal‐average intensity is less than 100 mW/cm ² . This study contributes significantly to the advancement of wearable ultrasound therapy.