Antibacterial, Self-Adhesive, Recyclable, and Tough Conductive Composite Hydrogels for Ultrasensitive Strain Sensing

Abstract

Owing to the characteristics of mimicking human skin's function and transmitting sensory signals, electronic skin (eskin), as an emerging and exciting research field, has inspired tremendous efforts in the biomedical field. However, it is frustrating that most e-skins are prone to bacterial infections, resulting a serious threat to human health. Therefore, the construction of e-skin with an integrated perceptual signal and antibacterial properties is highly desirable. Herein, the dynamic supramolecular hydrogel was prepared through a freezing/thawing method by cross-linking the conductive graphene (G), biocompatible polyvinyl alcohol (PVA), self-adhesive polydopamine (PDA), and in situ formation antibacterial silver nanoparticles (AgNPs). Having fabricated the hierarchical network structure, the PVA−G−PDA−AgNPs composite hydrogel with a tensile strength of 1.174 MPa and an elongation of 331% paves way for flexible e-skins. Notably, the PVA−G−PDA−AgNPs hydrogel exhibits outstanding antibacterial activity to typical pathogenic microbes (e.g., Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus), which effectively prevents bacterial infections that harm human health. With self-adhesiveness to various surfaces and excellent conductivity, the PVA−G−PDA−AgNPs composite hydrogel was used as strain sensors to detect a variety of macroscale and microscale human motions successfully. Meanwhile, the excellent rehealing property allows the hydrogel to recycle as a new sensor to detect large-scale human activities or tiny movement. Based on these remarkable features, the antibacterial, self-adhesive, recyclable, and tough conductive composite hydrogels possess the great promising application in biomedical materials.

Review of Materials and Fabrication Methods for Flexible Nano and Micro-Scale Physical and Chemical Property Sensors

“…Recyclability remains an issue in the fabrication of flexible electronic skins. Hydrogels are often used in the construction of these skins due to their ability to self-heal, however most of these skins can be re-used up to 3-5 times [94]. During recycling, electrical conductivity of the electronic skin can decrease slightly due to evaporation of a small amount of water in the hydrogel.…”

Review of Materials and Fabrication Methods for Flexible Nano and Micro-Scale Physical Property Sensors

“…The electronic skin can detect human motion, has self-healing properties and has the ability to distinguish direction [92] Recyclability remains an issue in the fabrication of flexible electronic skins. Hydrogels are often used in the construction of these skins due to their ability to self-heal however, most of these skins can be re-used up to 3-5 times [93]. During recycling, electrical conductivity of the electronic skin can decrease slightly due to evaporation of a small amount of water in the hydrogel.…”

Stretchable, self-healing and adhesive sodium alginate-based composite hydrogels as wearable strain sensors for expansion–contraction motion monitoring

“…, current, resistance, and capacitance) have aroused much attention and have progressed rapidly. 9–13 So far, conductive hydrogels can be readily prepared by incorporating various conductive materials such as ion electrolytes, 14–18 carbon-based nanomaterials, 19–23 metal nanoparticles and nanowires, 24,25 conductive polymers, 26,27 MXene, 28 and liquid metals 29,30 into flexible hydrogel substrates. As a typical kind of elastic material, conductive hydrogels usually possess an adjustable mechanical strength, satisfactory flexibility, and good conductivity.…”