Recent Progress in Bioinspired Design Strategies for Freeze Resistant Hydrogel Platforms toward Flexible Electronics

Lignin-Based Conductive Hydrogels with Plasticity, Recyclability, and Self-Adhesion as Flexible Strain Sensors for Human Motion Monitoring

“…The incorporation of conducting polymers that possess intrinsic electronic conductivity such as polyaniline (PANi), polypyrrole (PPy), and poly­(3,4-ethylenedioxythiophene)-poly­(styrenesulfonic acid) (PEDOT:PSS) into hydrogel matrices is a prevalent method for fabricating conductive hydrogels. − Among these polymers, PPy stands out as a conductive polymer with excellent electrical conductivity, admirable biocompatibility, remarkable redox properties, and significant environmental stability, rendering it particularly suitable for integration with hydrogel matrices. − Much of the previous research on conductive hydrogels has focused on elastic substrates with chemically cross-linked networks . These materials demonstrate the characteristic elastic behavior yet suffer from limited shape adaptability, immutable electromechanical properties upon solidification, and, in certain cases, potential toxicity manifested by some synthetic polymers, limiting their deployment in medical applications. ,− Moreover, the nonrecyclability of synthetic polymers is a major environmental challenge . With the rapid development of wearable devices, this could lead to an increase in electronic waste, posing a significant risk to the ecological environment. , …”

Homogenous Organohydrogel Mediated by Covalently-Converted Graphene Nanosheets as an Electronic Epidermis for Multimodal Perception and Soft Actuation

“…We believe that the imidazolium cation at the edge of the IL-GO sheets contributes to their hydrophilicity, while the graphene domain ensures the hydrophobicity, which further self-assembles into micelles to stabilize the hydrophobic fragment. In addition, wearable hydrogel devices are inevitably deteriorated in extreme environmental conditions. − Although the IL is a candidate solvent in achieving low-temperature tolerant hydrogels, it depresses the transfer of carriers when totally replacing water . Similarly, adding inorganic salts into the hydrogel is feasible to decrease its freezing point, but it disrupts the mechanical properties. , Another strategy to construct organohydrogels with superior antifreezing and moisturizing properties is the addition of organic solvents. ,,− Dimethyl sulfoxide (DMSO) possesses intrinsically high polarity and forms abundant hydrogen bonding with water molecules .…”