3D designed cellular solids for the case study of soft robotics

With the advances in technology, robots have tremendously evolved over the past decades, emerging a new paradigm in robotics, called soft robotics, which is largely inspired by the biological systems in nature, and are primarily composed of materials with mechanical moduli similar to that of soft biological materials. The material properties and morphology of the soft bodies can help in achieving the desired performance for the soft robot, by deforming, adapting, and reacting to interaction forces. Most of the soft robots have bodies made out of intrinsically soft and/or flexible materials (for example, silicone rubbers) that can deform and absorb most of the energy arising from a collision. These robotic bodies built with elastomer materials show lack of structural stiffness that limits their use in many practical applications. The objective of this study is to design specific cellular materials and integrate stiffness into soft robotic gripper bodies, by applying both engineering and architectural principles to form a lightweight and stiff body. An architectured cellular robotic body design is demonstrated, with deformable structures for a soft gripper, which is easy to fabricate, lightweight, mechanically durable, and compliant while maintaining its resilience. This cellular body design not only overcomes the stiffness limitation but also other drawbacks of most common pneumatically actuated soft bodies which includes getting easily damaged from high pressure or impact and exhibiting low gripping force due to their soft, deformable bodies. To form a functional system, artificial cellular finger is equipped together with capacitance based pressure sensors on the fingertip in a single-building process with the advantage of multi-material three-dimensional (3D) printing. The integrated architectured grippers, composed of cellular fingers with repeatably reliable bending profile, demonstrated an average gripping force as 16 N on actuation with gripping capability of various objects. It is highly expected that 3D cellular designs open new possibilities for architectured materials that can be used from robotic grippers to many practical applications.