Flexible sensitive hydrogel sensor with self-powered capability

Flexible sensitive hydrogels gain comprehensive research interests in fabricating human-machine interfacial devices. However, they face a great challenge of incompatibility among high strength, ultra-toughness and good conductivity, and count on an external power supply. In the work, 4-(methacryloyloxy) ethyl -1-phenylene acid (MBA) and 1,4-(5-hexenyloxy) benzene (RM26) are synthesized as supramolecular crosslinker and inserted into polyvinyl alcohol (PVA) hydrogel. A series of conductive hydrogels (PVA-PMR-NaCls) are produced by salt immersion method. The optimal PVA-PMR-NaCl exhibits the toughness of 15.92MJ.m(-3), the elongation at break of 600%, the tensile strength of 5.61 MPa and the Young's modulus of 2.16 MPa. It withstands the side effect of saline ions because the defined molecules with flexible chain segment and rigid group intervene. The conductivity for PVA-PMR-NaCl is 3.0 S.m(-1) prior to original PVA-NaCl owing to the carboxyl in network. It shows high gauge factor (GF) toward tensile strain, which achieves 6.24 above 200% strain. The PVA-PMR-NaCl sensor presents high sensitivity, stability and quick responsiveness during detecting human movement. Furthermore, the self-powered PVA-PMR-NaCl sensor by assembling with zinc foil and copper foil achieves the open circuit voltage of 0.809 V, and can likewise trace the stretching, bending and compressing movement according to current change. So, it will be a promising candidate as a self-powered multi-functional sensor.

Automated summary

Flexible sensitive hydrogels have gained significant research interest in the fabrication of human-machine interfacial devices. However, the challenge of achieving high strength, ultra-toughness, and good conductivity in hydrogels, as well as the dependence on an external power supply, remains a major obstacle. In this work, researchers synthesized supramolecular crosslinkers and inserted them into a polyvinyl alcohol hydrogel, resulting in conductive hydrogels with improved mechanical and electrical properties. The optimized hydrogel exhibited high toughness, elongation at break, tensile strength, and Young's modulus, and demonstrated resistance to the side effects of saline ions. The hydrogel also exhibited enhanced conductivity and sensitivity, making it a promising candidate for self-powered multi-functional sensors.