ReRobot: Recycled Materials for Trustworthy Soft Robots

Abstract

The ethical sourcing and disposal of materials has become ubiquitous and necessary across society. However, this trend towards increased sustainability has yet to find parallels in robotics research. Within the field of soft robotics, large quantities of silicones, rubbers and other elastomers are used to construct the various soft bodies and actuators. As the field grows, this will have a large negative impact on the environment. In this work we propose the effective recycling of elastomeric materials, thereby reducing the amount of new material needed, lowering costs and reducing the amount of harmful waste. We present a non-chemical process of elastomer recycle-and-reuse, where elastomeric material from old and broken soft actuators is ground into granules ranging from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\leq \boldsymbol{1}$</tex> mm in diameter to 3 mm in diameter and used to create new soft actuators without loss of function. Characterisation tests show that although ultimate yield strain and stress reduce with the percentage of recycled material, the silicone composites exhibit very comparable elastic properties to the pristine silicone. This suggests an effective recycling pipeline where materials are recycled into different, lower-risk, applications at each iteration. We demonstrate the effectiveness of this process in a high strain recycled bladder actuator and a soft gripper.