Thermoelectric Composites Based on Porous Laser-Induced Graphene and Ion Hydrogel

Despite the rapid development of single-modal flexible sensors, there is an urgent need to develop self-powered multimodal flexible sensing devices to eliminate power constraints. This work reports stretchable thermoelectric composites based on porous laser-induced graphene foams and an ion hydrogel, aiming to create a self-powered sensor that can detect temperature changes and strain with high accuracy. The self-powered strain sensor based on 3D porous laser-induced graphene (LIG) foam exhibits a high maximum sensitivity of 105.9 for strain up to 30%, a low detection limit of 0.071%, and good stability over 5,000 cycles at 30% strain. With an increased Seebeck coefficient of -189.90 μV/K, the sensor can also detect temperatures in the range of -10-100 °C with a resolution of 0.1 °C. The thermoelectric power generation array with integrated units can achieve an output voltage of 104.18 mV for a temperature difference of 20 °C. By combining the electronic thermoelectric material LIG and the ionic thermoelectric material NKKC/PFF, the dual-parameter sensors demonstrate high potential in human health monitoring, smart storage, and bathroom systems. The reported thermoelectric composites can be further utilized in temperature-strain decoupled sensing for battery monitoring, smart garments, and medical applications.