Biodegradable Dielectric Elastomer Actuators and Sensors

Soft robotics, a field dedicated to the development of robots using flexible and compliant materials, has undergone significant progress in recent years. Several features of soft robots including their physical adaptability to their surroundings, shockabsorption capabilities, and minimal risk of harm to humans and objects have rendered them ideal for various applications. However, most soft robots are fabricated using synthetic elastomeric materials, contributing to environmental pollution and degradation. A potential solution to this problem involves integrating biodegradability into the designs of soft robots, facilitating their degradation through microbial activity and subsequent integration into the soil. However, to achieve this functionality, biodegradable soft robotic elements must be developed. This paper presents biodegradable dielectric elastomer actuators (DEAs) and sensors (DESs). These devices feature a soft dielectric membrane with compliant electrodes on both sides, enabling them to function as both electrostatic actuators and capacitive sensors. Natural rubber and gelatin-based elastomeric materials are employed for the dielectric membrane and electrodes, respectively. Using these materials and established fabrication processes, experimental biodegradable DEA and DES samples are fabricated and characterized. The DEA with a circular actuator configuration demonstrates a voltagecontrollable areal strain of up to 15.4 ± 0.4% and presents stable operation over 1,000 actuation cycles. The DEA with a bending actuator configuration exhibits a voltage-controllable bending angle of up to 17.4 ± 1.9°. The DES demonstrates a linear response for strains up to 200%, with a gauge factor of 0.85 ± 0.017, and maintains stability over 10,000 strain cycles. The observed characteristics of the DEAs and DES align well with theoretical predictions, highlighting the potential applicability of biodegradable DEAs and DESs as promising elements for sustainable and environmentally friendly soft robots.