Investigation on developing a topology optimized and 3D printable multimaterial soft gripper

This paper proposes a systemic design and fabrication approach to automatically develop multimaterial soft robots. Composing of relatively softer and harder materials, these robots are expected to undergo larger deformation and exert higher payloads. However, it is more challenging to design such kind of robots by biomimetic or intuitive approach because of a larger design space comparing with their single-material counterparts. Herein, the structural design problem is recast as a topology optimization one, for example, a soft gripper can be modeled as a compliant mechanism aiming to achieve its maximal bending deflection. During the optimization process, both structure and material distribution are obtained automatically. Thereafter, the optimized multimaterial soft gripper is directly fabricated by 3D printing technique regardless of geometrical complexity and material composition. Characterization and grasping tests show that a single finger can undergo 17.15° free travel bending and exert 0.13 N grasping force under 0.02 MPa actuation pressure. The proposed systemic approach is strongly recommended to develop other types of soft robots by defining the corresponding topology optimization model.