An integrated design and fabrication strategy for entirely soft, autonomous robots.

Michael Wehner,George M Whitesides,Bobak Mosadegh,Robert J Wood,Ryan L Truby,Daniel J Fitzgerald,Jennifer A Lewis

doi:10.1038/nature19100

Abstract

Soft robots possess many attributes that are difficult, if not impossible, to achieve with conventional robots composed of rigid materials. Yet, despite recent advances, soft robots must still be tethered to hard robotic control systems and power sources. New strategies for creating completely soft robots, including soft analogues of these crucial components, are needed to realize their full potential. Here we report the untethered operation of a robot composed solely of soft materials. The robot is controlled with microfluidic logic that autonomously regulates fluid flow and, hence, catalytic decomposition of an on-board monopropellant fuel supply. Gas generated from the fuel decomposition inflates fluidic networks downstream of the reaction sites, resulting in actuation. The body and microfluidic logic of the robot are fabricated using moulding and soft lithography, respectively, and 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 fluidic and elastomeric architectures required for function span several orders of magnitude from the microscale to the macroscale. 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.

Highlights

The body and microfluidic logic of the robot are fabricated using moulding and soft lithography, respectively, and 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[13,14]
Monopropellant fuels have been suggested as a promising fuel source for pneumatically actuated soft robots[4,12]. Their rapid decomposition into gas upon exposure to a catalyst offers a strategy for powering soft robotic systems that obviates the need for batteries or external power sources
Matrix materials are poured into the mould (Fig. 1c) and the remaining soft robot features are embedded 3D (EMB3D) printed into the moulded matrix (Fig. 1d, e, Supplementary Video 1)

Summary

An integrated design and fabrication strategy for entirely soft, autonomous robots. Michael Wehner1,2*, Ryan L. The body and microfluidic logic of the robot are fabricated using moulding and soft lithography, respectively, and 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[13,14]. Moulded and laminated elastomers with embedded pneumatic networks are widely used materials in soft robotics[1,21,22] Actuation of these elastomeric composites occurs when interconnected channels that make up the pneumatic network are inflated with incompressible fluids or gases supplied via tethered pressure sources[1]. Monopropellant fuels have been suggested as a promising fuel source for pneumatically actuated soft robots[4,12] Their rapid decomposition into gas upon exposure to a catalyst offers a strategy for powering soft robotic systems that obviates the need for batteries or external power sources. We report a method for creating a completely soft, pneumatic robot—the ‘octobot’—with eight arms that are powered by monopropellant decomposition

Pt reaction chambers e f

Outlets b Fuel reservoirs

Pressure rate

Mould ii iii

METHODS

Two bladder actuators Four bladder actuators