Hierarchically Structured Stretchable Conductive Hydrogels for High-Performance Wearable Strain Sensors and Supercapacitors

Stretchable conductive materials, a critical building block of soft electronics, typically require multiple components that synergistically contribute good mechanical, electrical, and interfacial properties. The overall performance is often hindered by phase instability and poor miscibility of functional fillers within polymer matrices, compromising the conductive percolative network. We addressed this challenge with an ice-templated, low-temperature polymerization (ITLP) strategy and created stretchable conducting hydrogels. Owning a hierarchical dendritic microstructure with mitigated nanoaggregation, the material exhibited 29-fold enhancement in toughness and 83-fold increase in conductivity. Strain sensors using such gels demonstrated a broad detection range, high sensitivity, and health-monitoring capability. ITLP gel electrodes exhibited 888 F/g specific capacitance and 2,097 mF/cm(2) areal capacitance (368 F/g) when used in solid-state supercapacitors. Flexible and stretchable wearable supercapacitors have been successfully made and can power LEDs. The ITLP strategy is anticipated to create diverse high-performance soft-electronic materials for broad applications in energy, healthcare, and robotics.