Recoverable Dual-Modal Responsive Sensing Materials Based on Mechanoluminescence and Thermally Stimulated Luminescence toward Noncontact Tactile Sensors

Tactile sensing with stress and temperature sensing as core elements have shown promising prospects in intelligent robots and the human-machine interface. Mechanoluminescence (ML)-based stress sensing can realize the direct sensing of mechanical stimulation, whereas indirect temperature sensing based on luminescent sensing materials usually requires the stimulation of extra light or force. Herein, a trap-controlled material Sr2MgAl22O36:Mn2+ with bifunctional mechano/thermal sensing applications was developed and investigated in detail. Visualized bright green-emitting ML and thermally stimulated luminescence (TSL) directly and rapidly responded to mechano/thermal dual stimulation in the Sr2MgAl22O36:Mn2+/PDMS composite film. It is worth mentioning that this study proposed a new idea of direct temperature sensing by the initial intensity of TSL due to thermal-photo energy conversion, unlike previous temperature sensor technology. Based on this, we designed a flexible optical skin with a simple structure and verified its application prospect as a tactile sensing material with dual mechano/thermal response, establishing a unique imaging mode and providing a convenient, reliable, and sensitive way to remotely visualize the distribution of stress and temperature. This study paves a new way for the development of optical skins with simple structures and sensitive visibility in the application of intelligent robot tactile sensing.