Advances in conductive supramolecular hydrogels for applications in wearable electronics

Nature is full of fascinating examples where physical strategies help achieve adhesion, self-healing, climbing, and attachment. For instance, reptiles climb walls without falling to the ground, and DNA double helix reannealing, as well as protein folding and refolding, occur due to noncovalent interactions. Similarly, in the self-healing of human skin and the formation of water clusters, noncovalent interactions play a critical role. Hydrogels having noncovalent supramolecular interactions are renowned for their intricate structure and excellent mechano-responsive properties, establishing them as key materials for human-machine interactions, drug delivery, biosensors, strain sensors, energy storage, and energy harvesting systems. This review explains the mechanism of supramolecular interactions in conductive hydrogels (CHs), details comparative studies between conductive supramolecular polymer hydrogels (CSuPHs) and traditional hydrogels, and recent strategies for improving the mechanical strength of CSuPHs. Additionally, it discusses different types of flexible sensors based on supramolecular interactions and explains the emerging applications of CSuPHs in wearable electronics (human motion monitoring, strain and pressure sensing, wearable smart gloves, and sweat analysis), energy storage and harvesting systems (triboelectric nano-generator (TENG), piezo-electric nanogenerators (PENG)). It highlights the challenges exist and future prospects of CSuPHs.