High-Sensitivity Multiresponses Cellulose-Based Actuators with Configurable Amplitude

Actuators have many applications in artificial muscles, soft robots, and optical switches. Herein, we designed and fabricated a multifunctional actuator using cellulose composites that can be driven by humidity, natural sunlight, and electrothermal processes. Highly conductive and flexible cellulose, MXene, and PEDOT:PSS composite (CMPC) films were prepared with a facile blending-vacuum filtration method. Benefiting from the high conductivity, the CMPC film exhibited excellent performance in electromagnetic shielding, electrothermal processes, and humidity detection. Moreover, due to the hygroscopic properties of cellulose, CMPC film shows a negative coefficient of thermal expansion, in contrast to typical polymer films. By depositing a hydrophobic polytetrafluoroethylene (PTFE) film onto the CMPC film, a two-layer actuator was developed. Owing to the opposite thermal expansion properties of CMPC and PTFE, the as-obtained actuators exhibit a high sensitivity, and are made into bionic flowers, worms, robots, and smart curtains, showing fast responses to humidity, natural sunlight, and electrothermal processes. In fact, natural sunlight of 80 mW cm–2 or a power supply of as low as 3 V can drive the actuator to a bending curvature of 2.85 cm–1, corresponding to a bending angle of 360°. The bionic robot is configurable with movements and speeds that can be controlled by a microcontroller and have a wide application in biological bionic and soft robots.