Flexible piezoelectric thin-film energy harvesters and nanosensors for biomedical applications

The use of inorganic-based flexible piezoelectric thin films for biomedical applications has been actively reported due to their advantages of highly piezoelectric, pliable, slim, lightweight, and biocompatible properties. The piezoelectric thin films on plastic substrates can convert ambient mechanical energy into electric signals, even responding to tiny movements on corrugated surfaces of internal organs and nanoscale biomechanical vibrations caused by acoustic waves. These inherent properties of flexible piezoelectric thin films enable to develop not only self-powered energy harvesters for eliminating batteries of bio-implantable medical devices but also sensitive nanosensors for in vivo diagnosis/therapy systems. This paper provides recent progresses of flexible piezoelectric thin-film harvesters and nanosensors for use in biomedical fields. First, developments of flexible piezoelectric energy-harvesting devices by using high-quality perovskite thin film and innovative flexible fabrication processes are addressed. Second, their biomedical applications are investigated, including self-powered cardiac pacemaker, acoustic nanosensor for biomimetic artificial hair cells, in vivo energy harvester driven by organ movements, and mechanical sensor for detecting nanoscale cellular deflections. At the end, future perspective of a self-powered flexible biomedical system is also briefly discussed with relation to the latest advancements of flexible electronics.