Untethered, ultra-light soft actuator based on positively charged 3D fluffy silica micro-nanofibers by electrospinning

There is a growing interest in the design and fabrication of small-scale soft actuators and robotics, especially the realization of functionalities mimicking biological systems with biomimetic motions in response to external stimuli. However, the mobility and self-weight are still the critical challenges for further improvement and broader application of soft actuators. It is attractive to develop untethered and ultra-light small-scale robotics by integrating the actuators and drivers while achieving the ability to respond to external stimuli. Inspired by the spiders that rely on electrostatic forces in the environment to stay airborne by their ballooning silk, a positively charged fiber-paper structure-based soft actuator is proposed. Utilizing electrospinning of tetraethyl orthosilicate (TEOS) solution, this ultra-light soft actuator can realize the movement of bending and high-frequency vibration with the stimuli of electrostatic force in the electric field. Programmable motions, i.e., continuous bending with a series of angles, variable frequency vibration, can be realized by regulating the external electric field. The 3D fluffy structure of the silica micro-nanofibers and the paper-based structure endow the soft actuator with ultra-lightweight and excellent flexibility. The untethered, ultra-light soft actuator suggests a feasible approach to develop ultra-light, soft and autonomous robotics and holds promise in reconnaissance and environmental detection. Graphic abstract: [Figure not available: see fulltext.]