Soft robots possess many attributes that are difficult, if not impossible, to achieve with conventional robots composed of rigid materials 1,2. Yet, despite recent advances, soft robots must still be tethered to hard robotic control systems and power sources 3-10. 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 11 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 12. 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. 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. Soft robotics is a nascent field that aims to provide safer, more robust robots that interact with humans and adapt to natural environments better than do their rigid counterparts. Unlike conventional robots composed of rigid materials, soft robots based on hydrogels 15,16 , electroactive polymers 17 , granular media 18 and elastomers 5,19 exhibit elastic moduli ranging from 10 kPa to 1 GPa (ref. 1), are physically resiliant 7,20 and have the ability to passively adapt to their environment 1,2,19. 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. Robotic end effectors with bioinspired 10 and rapid 6 actuation, deployable crawlers 3,7 and swimmers 8 with complex body motions, and robust jumpers 9,23 have been developed on the basis of this design strategy. However, in each case, these robots are either tethered to or carry rigid systems for power and control, yielding hybrid soft-rigid systems 4,7-9. Creating a new class of fully soft, autonomous robots 24 is a grand challenge, because it requires soft analogues of the control and power hardware currently used. Recently, 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 batteri...

Soft robots actuated by pressurization and inflation of a pneumatic network (a "pneunet") of small channels in elastomeric materials are appealing for their ability to produce sophisticated motions with simple controls. Although current designs of pneu-nets achieve motion with large amplitudes, they do so relatively slowly (that is, over seconds). This paper describes a new design for pneu-nets that reduces the amount of gas that must be transported for inflation of the pneu-net, and thus increases its speed of actuation. A simple actuator can bend from a linear shape to a quasi-circular shape in 50 milliseconds when pressurized at ΔP = 345 kPa. At high rates of pressurization and inflation, the path along which the actuator bends depends on this rate. When inflated fully, the channels and chambers of this new pneu-net design experience only one-tenth the change in volume of that required for a motion of equal amplitude using the previous design. This small change in volume requires comparably low levels of strain in the material at maximum amplitudes of actuation, and commensurately low rates of fatigue and failure. This actuator can operate over a million cycles without significant degradation of performance. This design for soft robotic actuators combines high rates of actuation with high reliability of the actuator, and opens new areas of application for them.