Reverse electrowetting-on-dielectric (REWOD) human energy harvester towards hybridisation with piezoelectricity for self-powered wearable biosensors

Abstract. Wearable biosensors play a crucial role in modern healthcare, providing continuous monitoring of various physiological parameters. However, the reliance on batteries that require replacement introduces interruptions in the data acquisition process and patient discomfort, and for this reason, energy harvesting methods that convert human body energy into electricity have attracted considerable research interest. In this paper, the concept of an innovative hybrid energy harvester that combines piezoelectric and reverse electrowetting-on-dielectric (REWOD) techniques is introduced. The key working principle revolved around the electrical double layer present in the REWOD component and coupling it with a piezoelectric generator via an electret. By harnessing biomechanical vibrations with a piezoelectric material and the REWOD unit, the overall power output of the harvester was enhanced. The proposed design was evaluated through numerical simulations and a series of experimental tests. In the present work, experimental results on the influence of various design parameters on the amount of generated power through the REWOD process are presented, thus contributing to the advancement of self-powered, sustainable, wearable biosensors, enabling seamless and continuous data acquisition without relying on external batteries.