Fabrication of a biodegradable piezoelectric-based wearable sensor for non-invasive monitoring of dynamic human motions and physiological signals

Recent advancements in flexible sensors and piezoelectric materials have facilitated the progress of continuous monitoring systems in the form of wearable and implantable medical devices, enabling the monitoring of human physiological signals. However, the non-degradable nature of these materials has resulted in the accumulation of significant amounts of electronic waste (e-waste) and necessitated subsequent surgeries for device removal. In this study, we introduce a flexible and biodegradable piezoelectric material fabricated specifically for wearable and implantable devices. This material addresses the issues associated with secondary surgeries and e-waste while providing a high-performance platform for the continuous and seamless monitoring of human physiological signals and tactile stimuli. The innovative combination of bioresorbable poly (L-lactic acid) (PLLA) and glycine has resulted in the development of flexible piezoelectric devices capable of non-invasive measurement of artery pulse signals in near-surface arteries and detecting slight muscle movements, including those of the trachea, esophagus, and joints. Furthermore, we demonstrate the complete degradability of the piezoelectric film in a phosphate buffer saline (PBS) solution at a temperature of 37°C. The pressure sensor derived from this material exhibits a high sensitivity of 13.2 mV/kPa, with a response time of 10 ms, and demonstrates excellent mechanical stability. Additionally, this piezoelectric material showcases comparable performance to commonly used non-degradable counterparts for measuring physiological signals. Due to its degradable nature, it can also be employed in temporary implantable medical devices for monitoring purposes.