Comprehensive biocompatibility of nontoxic and high-output flexible energy harvester using lead-free piezoceramic thin film

Abstract

Flexible piezoelectric energy harvesters have been regarded as an overarching candidate for achieving self-powered electronic systems for environmental sensors and biomedical devices using the self-sufficient electrical energy. In this research, we realize a flexible high-output and lead-free piezoelectric energy harvester by using the aerosol deposition method and the laser lift-off process. We also investigated the comprehensive biocompatibility of the lead-free piezoceramic device using ex-vivo ionic elusion and in vivo bioimplantation, as well as in vitro cell proliferation and histologic inspection. The fabricated LiNbO3-doped (K,Na)NbO3 (KNN) thin film-based flexible energy harvester exhibited an outstanding piezoresponse, and average output performance of an open-circuit voltage of ∼130 V and a short-circuit current of ∼1.3 μA under normal bending and release deformation, which is the best record among previously reported flexible lead-free piezoelectric energy harvesters. Although both the KNN and Pb(Zr,Ti)O3 (PZT) devices showed short-term biocompatibility in cellular and histological studies, excessive Pb toxic ions were eluted from the PZT in human serum and tap water. Moreover, the KNN-based flexible energy harvester was implanted into a porcine chest and generated up to ∼5 V and 700 nA from the heartbeat motion, comparable to the output of previously reported lead-based flexible energy harvesters. This work can compellingly serve to advance the development of piezoelectric energy harvesting for actual and practical biocompatible self-powered biomedical applications beyond restrictions of lead-based materials in long-term physiological and clinical aspects.

Implantable Energy‐Harvesting Devices

“…In 2017, Jeong et al used aerosol deposition and a laser lift‐off processing method to fabricate an IVEH based on LiNbO 3 ‐doped (K,Na)NbO 3 (KNN) thin films. They implanted the device into a porcine chest, and about 5 V and 700 nA were generated by the motion from the heartbeat.…”

Potassium‐Sodium‐Niobate‐Based Thin Films: Lead Free for Micro‐Piezoelectrics

“…Compared with PZT film, the KNN‐based film is especially suitable for in vivo medical detection shown in Figure a. Lee's group from Korea Advanced Institute of Science and Technology demonstrates a high‐performance KNN‐based flexibly piezoelectric energy harvester (f‐PEH) used in the in vivo power harvesting shown in Figure b . They fabricated PZT film f‐PEH as a counterpart and made a comparison through a biological testing on porcine heart as shown in Figure b and tap water.…”

“…c) Original porcine electrocardiogram, in vivo generated energy harvesting voltage and current. Reproduced with permission . Copyright 2017, AIP Publishing LLC.…”

Modulation of surface physics and chemistry in triboelectric energy harvesting technologies

“…A piezoelectric energy harvester is one of the ways to harvest mechanical energy, which has been widely investigated by many researchers [18][19][20][21][22][23][24][25][26][27][28][29][30]. When a piezoelectric device is deformed by an external mechanical stress, a dipole moment is changed inside the piezoelectric material, and thereby an electric charge is generated [31][32][33][34][35][36][37].…”