Pressure-enhanced thermopower of ionic thermoelectric gelatin for identifying materials with different thermal conductivities

As the human body's most vital environmental interface, the skin integrates diverse sensory receptors enabling simultaneous perception of multiple stimuli through multisensory processing. However, the realization of multifunctional sensing system on robots or prosthetics remains a huge challenge. Here we report a multifunctional tactile sensor fabricated from ionic thermoelectric gelatin that achieves simultaneous pressure and temperature detection. The thermoelectric effect of this ionic thermoelectric gelatin is mainly achieved through the synergy of the thermodiffusion effects and the thermogalvanic effect of ions. In addition, by applying pressure, the thermoelectric effect of this ionic thermoelectric gelatin can be changed (the thermopower of the ionic thermoelectric gelatin increases from 1.21 mV/K to 1.67 mV/K, representing a 38 % increase), so as to enable the sensor to sense external forces. By comparing the thermoelectric effect driven by temperature difference and the thermoelectric effect driven by pressure-temperature difference, there is a difference in the voltage response time. This allows for the decoupling of signals at the backend with only a simple algorithm. Using this sensor, we achieved a 95.31 % accuracy rate in identifying different materials. The multifunctional tactile sensor can promote the development of robots and better assist the disabled in restoring their sensory abilities.