3D Printed Auxetic Structure‐Assisted Piezoelectric Energy Harvesting and Sensing

Abstract

The fast development of wearable electronic systems requires a sustainable energy source that can harvest energy from the ambient environment and does not require frequent charging. Piezoelectric polymer films are a perfect candidate for fabricating piezoelectric nanogenerators (PENGs) to harvest mechanical energy from the environment due to their flexibility, good piezoelectricity, and environmental‐independent stable performance because of their inherent polarization. However, most of their applications are limited to the pressing mode energy harvesting that is based on the 3‐3‐direction piezoelectric effect due to the molecular polarization and nonstretchability. In this work, by 3D printing an auxetic structure on a polymer film‐based PENG, the bending deformation of the PENG can be transformed into the well‐controlled in‐plane stretching deformation, enabling the 3‐1‐direction piezoelectric effect. The synclastic effect of the auxetic structure is applied in flexible energy harvesting device for the first time, which makes the previously untapped bending deformation on a film a valuable device for energy harvesting and increases the bending output voltage of the PENG by 8.3 times. The auxetic structure‐assisted PENG is also demonstrated as a sensor to sense the bending angle and monitor the motion by mounting on different joints of the human body and soft robotic finger.

Age of Flexible Electronics: Emerging Trends in Soft Multifunctional Sensors

“…[ 189 ] This increase is attributed to the ferroelectret effect created by voids around the BTO particles within the PVDF‐TrFE matrix. Similarly, PVDF‐based polymer composites incorporating zinc oxide (ZnO) [ 190 ] and surface‐treated BTO [ 191 ] have demonstrated improved piezoelectric outputs and hence, sensing performance. However, even with these enhancements, the piezoelectric outputs of these composites still lag behind those of commonly used inorganic piezoelectric materials, prompting the need for further advancements in this field.…”

Hydrogel-Based Energy Harvesters and Self-Powered Sensors for Wearable Applications

“…The rapid advancement of wearable electronic systems necessitates a sustainable energy source capable of extracting energy from the surrounding environment without frequent recharging. Piezoelectric nanogenerators (PENGs) offer a potential solution by converting irregular and scattered mechanical energy from the environment into electrical energy, providing a long-term and continuous power supply for mobile distributed electronic devices [63][64][65]. In the realm of piezoelectric materials, polyvinylidene fluoride (PVDF) and its copolymers have garnered attention for their unique electrical properties, high flexibility, excellent mechanical processability, and long-term stability, making them promising materials for PENGs [66][67][68][69].…”