3D printing of very soft elastomer and sacrificial carbohydrate glass/elastomer structures for robotic applications

Abstract

Recently, soft materials such as silicone elastomers are widely used in soft robotics due to their high flexibility and safe physical interaction with humans. Focusing on three aspects—highly elastic materials, sacrificial materials, and actuation units, we aim to develop an additive manufacturing strategy that allows the fabrication of highly elastic soft structures more efficiently. First, silicone thinner is used to tailor the mechanical properties of the soft silicone elastomer. We found out that adding 20% volume thinner to the silicone improved the ultimate tensile elongation of 3D printed silicone samples upto 1260%, which is the highest among all the 3D printed soft materials previously reported. However, in a cyclic tensile test, this strain is not achieved; instead, the maximum strain was 600%. Second, carbohydrate glasses are introduced as sacrificial materials for 3D printing silicone with hollow channels. Few configurations of pneumatic and hydraulic actuators are developed by forming channels in the silicone elastomer via 3D printed sacrificial carbohydrate structures and subsequently dissolving. The 3D printed structures actuated successfully to get morphed shapes, which showed that our method is effective for manufacturing of functional soft robotic structures.