A self-sensing photoactuator based on temperature self-compensated MXene/graphite composite ink for objects recognition and biomimetic soft robotics

Soft actuators endowed with self-sensing capability become highly sought after in recent years. Ti₃C₂T_x MXene is expected to be used in the development of self-sensing actuators due to its outstanding physical and chemical properties. However, achieving precise deformation feedback of MXene-based actuators remains a challenge, as the resistance change of MXene is not only affected by deformation, but also by temperature, and the decoupling is difficult. Here, a composite ink with temperature self-compensation (0.00125 %·°C⁻¹ of temperature coefficient of resistance) is fabricated by combining MXene and graphite with opposite temperature coefficients of resistance. The composite ink can be written on a variety of substrates, including glass, cellulose paper, and various polymers. Based on this, an ink-cellulose/polymer composite actuator with self-sensing function is actualized. The actuator can achieve accurate real-time deformation feedback by monitoring the resistance signal of ink-cellulose layer, which shows a high linear sensitivity (gauge factor ~ 14.5, coefficient of determination (R²) > 0.99), thereby realizing the perception of touch behavior and distinguishing objects with different weights, softness, and roughness. Besides, a series of biomimetic devices and soft robots with programmable movements (rolling and self-sustained oscillating) are also demonstrated. The results offer new insights for the development of the self-sensing actuators.