Autonomous self-repair in piezoelectric molecular crystals

Abstract

Living tissue uses stress-accumulated electrical charge to close wounds. Self-repairing synthetic materials, which are typically soft and amorphous, usually require external stimuli, prolonged physical contact, and long healing times. We overcome many of these limitations in piezoelectric bipyrazole organic crystals, which recombine following mechanical fracture without any external direction, autonomously self-healing in milliseconds with crystallographic precision. Kelvin probe force microscopy, birefringence experiments, and atomic-resolution structural studies reveal that these noncentrosymmetric crystals, with a combination of hydrogen bonds and dispersive interactions, develop large stress-induced opposite electrical charges on fracture surfaces, prompting an electrostatically driven precise recombination of the pieces via diffusionless self-healing.

Performance Assessment and Comparison of Two Piezoelectric Energy Harvesters Developed for Pavement Application: Case Study

“…Figure 5 contains the profiles of the voltage waveform in the half pile-unit-based array and half bridge-unit-based array under the matched load resistance. The output power was calculated by integrating the response time and the measured voltage using (10). Figure 5a illustrates that the output voltage of the half pile-unit-based array was approximately 300 V and the output power generated was 1.7 mW with an optimal resistance of 10.0 MΩ.…”

“…Pavements are subjected to more than millions of vehicles loads, thus generating remarkable mechanical energy during their service life. Based on the positive piezoelectric effect of piezoelectric materials [9,10], piezoelectric energy harvesters (PEHs) can convert this kinetic energy into electrical energy (5). The developed PEHs can be utilized to power low-power sensors for traffic flow monitoring [11], structural health monitoring [8], and vehicle weight estimation [12], as well as to power electronics, such as signals, lights, and Internet of things systems [13,14].…”

An Array of Flag-Type Triboelectric Nanogenerators for Harvesting Wind Energy

“…In addition, some scholars proposed the "all-in-one package" technology containing both TENG and PNG, which have great potential in harvesting energy from water waves (blue energy), airflow (wind energy), sound frequency (acoustic energy), vibrations/mechanical motions (such as body motions activities/sleeping), and in vivo body motions. These harvesting technologies are expected to dominate the future smart world [19][20][21][22].…”

Recent Progress in the Energy Harvesting Technology—From Self-Powered Sensors to Self-Sustained IoT, and New Applications

“…Previously, there has already been an abundance of piezoelectric materials such as single-crystal piezoelectric ceramic lead magnesium niobate-lead zirconate titanate (PMN-PZT), barium titanate (BaTiO3), zinc oxide (ZnO), poly(vinylidene fluoride) (PVDF), and its copolymer, poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) [73,[92][93][94][95]. The piezoelectric technology also has received flourishing development and has shown remarkable performance for energy harvesting in the past few decades [96][97][98][99][100][101]. In 2006, Wang et al firstly used zinc oxide nanowire arrays to develop the PENG for electricity generation from tiny ambient movements [88].…”