Ultra-adhesive Poly(acrylic acid)-Based Hydrogel as a Flexible Sensor for Capturing Human-Motion Signal

Abstract

Conductive hydrogels are widely applied in wearable sensors, soft robotics, and human-interactive devices owing to their unique physicochemical properties. Herein, we prepared an ultra-adhesive poly(acrylic acid)/Fe b /Li 2 SO 4c hydrogel. The maximum peeling forces of the hydrogel with respect to an aluminum substrate and a titanium surface were 1380 and 1619 N•m −1 , respectively. The elongation at break of the hydrogel was 2450%, and the breaking stress was 98 kPa. Owing to the synergistic effect of the −COOH−Fe 3+ complex and H bonds, the prepared hydrogels exhibited self-healing properties. Because of the presence of lithium sulfate, the hydrogel exhibited electrical conductivity (up to 0.0195 S•cm −1 ). The hydrogel could be used as a strain sensor with a gauge factor of 21.12. The high sensitivity of the hydrogel enabled it to quickly respond to changes in the speed and angle of human joint movements. Therefore, the hydrogel sensor could capture signals from lowamplitude movements such as speaking, smiling, and frowning. The simple preparation strategy for an adhesive, self-healing, frostresistant, and conductive hydrogel reported herein can broaden the range of applications of wearable electronic devices.

Ultra-stretchable, fast self-healing, adhesive, and strain-sensitive wearable sensors based on ionic conductive hydrogels

“…Moreover, a large hysteresis loop is observed during the first cycle, indicating greater dissipation of energy during deformation due to the dissociation of hydrogen bonds and coordination bonds in the first loading–unloading test. 55 Hysteresis loops became narrow after the first cycle and remained relatively stable. This is attributed to the internal structure of the hydrogel being able to recover spontaneously within a brief timeframe after the initial cycle.…”

Highly Stretchable, Fast Self-Healing, Self-Adhesive, and Strain-Sensitive Wearable Sensor Based on Ionic Conductive Hydrogels

“…From the second cyclic test, the hysteresis loop and the dissipation energy decrease substantially and exhibit good stability. It may be attributed to some of the hydrogen bonds, and metal coordination within the hydrogel was broken in the first loading–unloading test . Following this, the internal structure of the hydrogel is capable of self-recovery within a brief time frame, coupled with the presence of an energy dissipation mechanism and fatigue resistance after the initial cycle.…”

Multi-role conductive hydrogels for flexible transducers regulated by MOFs for monitoring human activities and electronic skin functions

“…Flexible transducers have garnered significant attention for their broad range of potential applications, including electronic skin, [1][2][3] human movement detection, [4][5][6] health monitoring, [7][8][9] and energy storage. [10][11][12] These transducers can differentiate between biological and mechanical activities, transmitting feedback through changes in their electrical output.…”