Transient implantable medical devices based on biodegradable electronics can be used for diagnostic and therapeutic purposes for a desired duration and undergo biodegradation, unlike their conventional counterparts. However, powering transient implants through biodegradable power sources remains under-explored. Here, we report biodegradable piezoelectric transducer fabricated using 0-3 composite film made of barium titanate nanoparticles and poly (L-lactic-co-glycolic) acid polymer (BT-PLGA). The proposed BT-PLGA can be utilized in two different powering schemes; ultrasonic powering and energy harvesting from low frequency acoustic waves. We demonstrated that the power density of the BT-PLGA transducer can reach up to 10 mW/cm2 in ultrasonic powering. The energy harvesting from low frequency acoustic waves could also readily generate sufficient power for small electronics. The fabricated transducers underwent complete biodegradation in physiological conditions within 100 days. The development of the biodegradable piezoelectric transducer potentially provides a reliable power source for transient implants, especially for deeply seated bioelectronics. The output performance, biocompatibility, and tunable biodegradation of BT-PLGA transducer demonstrate its potential as a biodegradable power source for transient implantable devices.

Wireless monitoring of the physio-biochemical information is becoming increasingly important for healthcare. In this work, we present a proof-of-concept hydrogel-based wireless biochemical sensing scheme utilizing ultrasound. The sensing system utilizes silica-nanoparticle embedded hydrogel deposited on a thin glass substrate, which presents two prominent interfaces for ultrasonic backscattering (tissue/glass and hydrogel/glass). To overcome the effect of the varying acoustic properties of the intervening biological tissues between the sensor and the external transducer, we implemented a differential mode of ultrasonic back-scattering. Here, we demonstrate a wireless pH measurement with a resolution of 0.2 pH level change and a wireless sensing range around 10 cm in a water tank.

Park J, et al. Yonsei Med J. 2023 Apr;64(4):233-242. https://doi.org/10.3349/ymj.2022.0422