fig2

Figure 2. Representative endogenous and exogenous powering strategies for piezoelectric nanogenerator-based systems. (A) In vivo cardiac biomechanical energy harvesting: a flexible piezoelectric energy harvester integrated on the epicardium (between the left-ventricular apex and the right ventricle, and between the atrioventricular groove and the right-ventricular outflow tract) converts cardiac contraction into voltage outputs, adapted from Ref.^[79] under CC BY 4.0 license. (B) Mesoporous PVDF/PDMS piezoelectric nanogenerator with a tissue-matched mechanical modulus for harvesting energy from pulsatile liquid pressure (simulated blood pressure), adapted with permission from Ref.^[82]. Copyright © 2016 Wiley-VCH. (C) In vivo piezoelectric characterization of an electrospun P(VDF-TrFE) nerve conduit bridging the rat sciatic nerve and the outline of the animal experiments, Adapted from Ref.^[73] under CC BY 4.0 license. (D) AI-driven gait monitoring using a P3HB/ZnO piezoelectric nanofiber smart insole: multichannel voltage outputs, plantar-pressure mapping, and gait recognition, adapted from Ref.^[85]. under the CC BY 4.0 license. (E) Ultrasound-driven peripheral neuromodulation using a ferroelectret NeuroRing wrapped around the sciatic nerve, adapted from Ref.^[12] under CC BY 4.0 license.