Conductive Hydrogel- and Organohydrogel-Based Stretchable Sensors

Abstract

Conductive hydrogels have drawn significant attention in the field of stretchable/wearable sensors due to their intrinsic stretchability, tunable conductivity, biocompatibility, multistimuli sensitivity, and self-healing ability. Recent advancements in hydrogel- and organohydrogel-based sensors, including a novel sensing mechanism, outstanding performance, and broad application scenarios, suggest the great potential of hydrogels for stretchable electronics. However, a systematic summary of hydrogel- and organohydrogel-based sensors in terms of their working principles, unique properties, and promising applications is still lacking. In this spotlight, we present recent advances in hydrogel- and organohydrogel-based stretchable sensors with four main sections: improved stability of hydrogels, fabrication and characterization of organohydrogel, working principles, and performance of different types of sensors. We particularly highlight our recent work on ultrastretchable and high-performance strain, temperature, humidity, and gas sensors based on polyacrylamide/carrageenan double network hydrogel and ethylene glycol/glycerol modified organohydrogels obtained via a facile solvent displacement strategy. The organohydrogels display higher stability (drying and freezing tolerances) and sensing performances than corresponding hydrogels. The sensing mechanisms, key factors influencing the performance, and application prospects of these sensors are revealed. Especially, we find that the hindering effect of polymer networks on the ionic transport is one of the key mechanisms applicable for all four of these kinds of sensors.

Highly Stretchable, Tough, and Conductive Ag@Cu Nanocomposite Hydrogels for Flexible Wearable Sensors and Bionic Electronic Skins

“…Then, two conductive copper sheets with copper wires were tightly fixed at the two ends of the sample and assembled into a strain sensor. [ 55 ] The hydrogel was sandwiched between two medical PU tapes. [ 56,57 ] The double medical PU tapes were used to prevent evaporation of water and increase the adhesion to human body.…”

Wearable Biofuel Cells: Advances from Fabrication to Application

“…The successful applications of these hydrogels in wearable devices indicate a great potential for hydrogel applications in near-future wearable products. [168] In addition, methods such as elastomer/plastic film wrapping to limit water evaporation can be employed in the meantime.…”

All-in-One High-Power-Density Vibrational Energy Harvester with Impact-Induced Frequency Broadening Mechanisms

“…Figure 5c shows the designed nonlinear piezoelectric power generation module of the bending fixture. The elastic restoring force F r = K eq (u)u(t) is added to the established theoretical general model of the nonlinear piezoelectric power generation module to obtain the theoretical model of the nonlinear piezoelectric power generation module of the bending fixture, as shown in Equation (6).…”

“…Therefore, researchers hope to design some devices to harvest the energy in the environment to power these microelectronic systems autonomously. Meanwhile, these low-power electronic devices pose a challenge to cheap, flexible, portable, and sustainable energy resources [2][3][4][5][6][7][8][9]. Therefore, many researchers are devoted to the demand of these microelectronic systems, among which vibration energy harvesting technology has become a research hotspot [10][11][12][13][14][15][16][17][18][19][20][21].…”