A Highly Mechanical, Conductive, and Cryophylactic Double Network Hydrogel for Flexible and Low-Temperature Tolerant Strain Sensors

Abstract

Due to their stretchability, conductivity, and good biocompatibility, hydrogels have been recognized as potential materials for flexible sensors. However, it is still challenging for hydrogels to meet the conductivity, mechanical strength, and freeze-resistant requirements in practice. In this study, a chitosan-poly (acrylic acid-co-acrylamide) double network (DN) hydrogel was prepared by immersing the chitosan-poly (acrylic acid-co-acrylamide) composite hydrogel into Fe2(SO4)3 solution. Due to the formation of an energy-dissipative chitosan physical network, the DN hydrogel possessed excellent tensile and compression properties. Moreover, the incorporation of the inorganic salt endowed the DN hydrogel with excellent conductivity and freeze-resistance. The strain sensor prepared using this DN hydrogel displayed remarkable sensitivity and reliability in detecting stretching and bending deformations. In addition, this DN hydrogel sensor also worked well at a lower temperature (−20 °C). The highly mechanical, conductive, and freeze-resistant DN hydrogel revealed a promising application in the field of wearable devices.

Investigation of Soft Matter Nanomechanics by Atomic Force Microscopy and Optical Tweezers: A Comprehensive Review

“…Then, Young’s modulus can be obtained from Equation (1). Tensile testing experiments have been carried out to address the mechanical properties of biodegradable cornstarch- [ 112 ], starch/dolomite- [ 113 ] or lignocellulosic- [ 114 , 115 ] based polymers, hydrogels made by carbon dots, hydroxyapatite and polyvinyl acetate [ 116 ] or chitosan-poly (acrylic acid-co-acrylamide) double network [ 117 ], natural-rubber-modified flame-retardant organic montmorillonite [ 118 ] or chlorhexidine-loaded poly (amido amine) [ 119 ] dendrimers, blends consisting of fibrillar polypropylene and polyethylene terephthalate [ 120 ] or poly ε-caprolactone/poly-(lactide-co-ε-caprolactone (PLCL) [ 121 ], polyurethane [ 122 ] and polyethylene [ 123 ] foams, organosilicone elastomer liquid crystals [ 124 ], and skeletal muscle tissues [ 125 ] or PLCL layered sheets with mesenchymal stem cells [ 126 ].…”

Herbal molecule-mediated dual network hydrogels with adhesive and antibacterial properties for strain and pressure sensing

“…Recently, dual network (DN) hydrogels, first established in 2003 by Gong et al , 14 have been recently demonstrated to be effective in constructing flexible sensors possessing enhanced physicochemical properties and integrated multifunctionality. 15–18 For example, Li et al fabricated a tough DN hydrogel through combining thermoreversible κ-carrageenan hydrogel with polyacrylamide network, where the former rendered good recoverability and self-healing capability to the DN hydrogel while the latter enabled 3D printing by means of UV light-triggered photopolymerization. 19 Gu et al employed the host–guest interaction and dynamic covalent bond to prepare DN hydrogels, acquiring satisfactory comprehensive performance including stretchability, strength, remodeling ability, self-healing property, self-adhesiveness, and biocompatibility.…”

Dual Network Hydrogel with High Mechanical Properties, Electrical Conductivity, Water Retention and Frost Resistance, Suitable for Wearable Strain Sensors

“…An effective method to improve the freezing resistance of hydrogel is to permeate organic solvents [ 19 ]. Inspired by the oil-water system, Rong et al [ 20 ] reported an antifreezing conductive organic hydrogel using H 2 O/Ethylene (Eg) dual solvent as the dispersion medium.…”