Fully Degradable, Highly Sensitive Pressure Sensor Based on Bipolar Electret for Biomechanical Signal Monitoring

In view of the global ecosystem crisis resulting from the ubiquitous electronic waste (e- and plastic waste), the engineering of advanced electronic devices from sustainable materials is gaining considerable attention. Nevertheless, the development of advanced, maybe even degradable electronics with comparable or even improved functionality remains a great challenge. In this article a fabrication process for a fully degradable, highly sensitive pressure sensor based on electrets is proposed enabling the creation of a universal platform for monitoring various biomechanical signals. The high sensitivity of the proposed biomechanical electret-based sensor utilizes electrostatic induction of highly deformable cellular polylactic acid (PLA) films with a serrated ripple structure and an improved bipolar charge storage capability. This biodegradable pressure sensor possesses competitive mechanical signal detection performance, obtaining a high pressure sensitivity (10 V/kPa), robust working stability (∼30,000 continuous cycles), short electromechanical response/recovery time (∼17 ms), and satisfactory heat resistance up to 60 °C. By tailoring the thickness of the encapsulation layer, the functional lifetime of the biomechanical sensor in physiological environment can be controlled effectively, facilitating adaptability to various implantable application scenarios. Altogether, the present work not only proposes an effective fabrication process for high-performance pressure sensors, but also provides new insight into the design of sustainable electronics with controllable lifetime thereby minimizing their environmental footprint. The developed sensor promises great potential in monitoring multiple biomechanical signals inside and outside the human body (e.g., body movements and physiological activities) as well as an environment-friendly realization of green electronics.