Person:

Wehner, Michael

A pneumatically powered, fully untethered mobile soft robot is described. Composites consisting of silicone elastomer, polyaramid fabric, and hollow glass microspheres were used to fabricate a sufficiently large soft robot to carry the miniature air compressors, battery, valves, and controller needed for autonomous operation. Fabrication techniques were developed to mold a 0.65-meter-long soft body with modified Pneu-Net actuators capable of operating at the elevated pressures (up to 138 kPa) required to actuate the legs of the robot and hold payloads of up to 8 kg. The soft robot is safe to interact with during operation, and its silicone body is innately resilient to a variety of adverse environmental conditions including snow, puddles of water, direct (albeit limited) exposure to flames, and the crushing force of being run over by an automobile.

Soft robots possess many attributes that are difficult, if not impossible, to realize with conventional robots composed of rigid materials. Yet, despite recent advances, soft robots still remain tethered to hard robotic control systems and power sources. New strategies for creating completely soft robots, including soft analogs of these crucial components, are needed to realize their full potential. Here, we report the first untethered operation of a robot comprised solely of soft materials. The robot is controlled with microfluidic logic that autonomously regulates the catalytic decomposition of an on-board monopropellant fuel supply. Gas generated from fuel decomposition inflates fluidic networks downstream of the reaction sites, resulting in actuation. The robot’s body and microfluidic logic are fabricated by molding and soft lithography, respectively, while the pneumatic actuator networks, on-board fuel reservoirs and catalytic reaction chambers needed for movement are patterned within the body via a multi-material, embedded 3D printing technique. The relevant length scales of fluidic and elastomeric architectures required for function spanned several orders of magnitude. Our integrated design and rapid fabrication approach enables the programmable assembly of multiple materials within this architecture, laying the foundation for completely soft, autonomous robots.