Using an environmentally benign and degradable elastomer in soft robotics

This work introduces an environmentally benign and degradable elastomer, poly(glycerol sebacate) with calcium carbonate (PGS-CaCO3), for use in soft robotics. Development of greener materials like PGS-CaCO3 contributes to robot designs that do not require retrieval and can safely degrade in the natural environment. A simplified synthesis method of PGS was used to create elastomer sheets, which were laser cut/rastered then laminated with cyanoacrylate glue into pneumatic soft actuators. The modified polymer synthesis method is accessible for roboticists and the three chemicals used are non-hazardous and inexpensive. Three accordion-style pneumatic actuators (3, 4 and 5 chambers) were characterized for free displacement and blocked force in both linear extension and curling motions, and an additional four 3-chambered actuators were also tested to leakage and failure. Material characterization of PGS-CaCO3 samples of all ages gave: ultimate tensile strength (UTS) from 48 to 160 kPa, elongation percent at UTS from 157 to 242%, moduli from 45 to 154 kPa, average resilience of 88% at 100 cycles, and maximum compressive force of 246 N at 50% strain. After being in an approximately 50-55 degrees C compost pile for 7 days, the polymer visibly degraded and had an average mass loss of 20% across 12 samples. PGS's strength, elasticity, biodegradability and chemical safety make it a desirable option for roboticists looking to leverage sustainable materials. PGS may also prove a potential green alternative for robotics applications in ubiquitous environmental and infrastructure sensing.