A soft, bistable valve for autonomous control of soft actuators

An entirely soft valve uses a snap-through instability to integrate autonomous control functions into soft actuators. Almost all pneumatic and hydraulic actuators useful for mesoscale functions rely on hard valves for control. This article describes a soft, elastomeric valve that contains a bistable membrane, which acts as a mechanical “switch” to control air flow. A structural instability—often called “snap-through”—enables rapid transition between two stable states of the membrane. The snap-upward pressure, ΔP1 (kilopascals), of the membrane differs from the snap-downward pressure, ΔP2 (kilopascals). The values ΔP1 and ΔP2 can be designed by changing the geometry and the material of the membrane. The valve does not require power to remain in either “open” or “closed” states (although switching does require energy), can be designed to be bistable, and can remain in either state without further applied pressure. When integrated in a feedback pneumatic circuit, the valve functions as a pneumatic oscillator (between the pressures ΔP1 and ΔP2), generating periodic motion using air from a single source of constant pressure. The valve, as a component of pneumatic circuits, enables (i) a gripper to grasp a ball autonomously and (ii) autonomous earthworm-like locomotion using an air source of constant pressure. These valves are fabricated using straightforward molding and offer a way of integrating simple control and logic functions directly into soft actuators and robots.

[1]  A. Haghiri-Gosnet,et al.  Logic digital fluidic in miniaturized functional devices: Perspective to the next generation of microfluidic lab‐on‐chips , 2017, Electrophoresis.

[2]  Filip Ilievski,et al.  Multigait soft robot , 2011, Proceedings of the National Academy of Sciences.

[3]  Robert J. Wood,et al.  A Resilient, Untethered Soft Robot , 2014 .

[4]  W. Menz,et al.  Microvalves with bistable buckled polymer diaphragms , 1996 .

[5]  Thomas J. Wallin,et al.  3D printing antagonistic systems of artificial muscle using projection stereolithography , 2015, Bioinspiration & biomimetics.

[6]  Mark A Burns,et al.  Microfluidic pneumatic logic circuits and digital pneumatic microprocessors for integrated microfluidic systems. , 2009, Lab on a chip.

[7]  G. Whitesides,et al.  Pneumatic Networks for Soft Robotics that Actuate Rapidly , 2014 .

[8]  D. J. Montgomery,et al.  The physics of rubber elasticity , 1949 .

[9]  Derek E. Moulton,et al.  Dynamics of snapping beams and jumping poppers , 2013, 1310.3703.

[10]  Kevin O'Brien,et al.  Optoelectronically innervated soft prosthetic hand via stretchable optical waveguides , 2016, Science Robotics.

[11]  L. Mahadevan,et al.  annularsector from Grasping with a soft glove: intrinsic impedance control in pneumatic actuators , 2017 .

[12]  G. Whitesides,et al.  Buckling Pneumatic Linear Actuators Inspired by Muscle , 2016 .

[13]  Aaron D. Mazzeo,et al.  Rotary Actuators Based on Pneumatically Driven Elastomeric Structures , 2016, Advanced materials.

[14]  Philip N Duncan,et al.  Scaling of pneumatic digital logic circuits. , 2015, Lab on a chip.

[15]  Alan N. Gent,et al.  Elastic instabilities in rubber , 2005 .

[16]  Chandana Paul,et al.  Morphological computation: A basis for the analysis of morphology and control requirements , 2006, Robotics Auton. Syst..

[17]  Michael Gomez,et al.  Passive Control of Viscous Flow via Elastic Snap-Through. , 2017, Physical review letters.

[18]  S. Quake,et al.  Monolithic microfabricated valves and pumps by multilayer soft lithography. , 2000, Science.

[19]  C. Keplinger,et al.  Harnessing snap-through instability in soft dielectrics to achieve giant voltage-triggered deformation , 2012 .

[20]  Stephen A. Morin,et al.  Using explosions to power a soft robot. , 2013, Angewandte Chemie.

[21]  Yong-Lae Park,et al.  Design and Fabrication of Soft Artificial Skin Using Embedded Microchannels and Liquid Conductors , 2012, IEEE Sensors Journal.

[22]  B. Mosadegh,et al.  Integrated Elastomeric Components for Autonomous Regulation of Sequential and Oscillatory Flow Switching in Microfluidic Devices , 2010, Nature physics.

[23]  L Mahadevan,et al.  Grasping with a soft glove: intrinsic impedance control in pneumatic actuators , 2017, Journal of The Royal Society Interface.

[24]  Shuichi Takayama,et al.  Control of soft machines using actuators operated by a Braille display. , 2014, Lab on a chip.

[25]  Matteo Cianchetti,et al.  Soft robotics: Technologies and systems pushing the boundaries of robot abilities , 2016, Science Robotics.

[26]  Filip Ilievski,et al.  Soft robotics for chemists. , 2011, Angewandte Chemie.

[27]  Robert J. Wood,et al.  Pneumatic Energy Sources for Autonomous and Wearable Soft Robotics , 2014 .

[28]  Katia Bertoldi,et al.  Amplifying the response of soft actuators by harnessing snap-through instabilities , 2015, Proceedings of the National Academy of Sciences.

[29]  Stephen A. Morin,et al.  Soft Robotics: Review of Fluid‐Driven Intrinsically Soft Devices; Manufacturing, Sensing, Control, and Applications in Human‐Robot Interaction   , 2017 .

[30]  Xin Chen,et al.  Soft Mobile Robots with On-Board Chemical Pressure Generation , 2011, ISRR.

[31]  Paulo B. Gonçalves,et al.  Dynamic non-linear behavior and stability of a ventricular assist device , 2003 .

[32]  Cagdas D. Onal,et al.  Soft robot actuators using energy-efficient valves controlled by electropermanent magnets , 2011, 2011 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[33]  Fionnuala Connolly,et al.  Automatic design of fiber-reinforced soft actuators for trajectory matching , 2016, Proceedings of the National Academy of Sciences.

[34]  Robert J. Wood,et al.  An integrated design and fabrication strategy for entirely soft, autonomous robots , 2016, Nature.

[35]  G. Whitesides,et al.  Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane). , 1998, Analytical chemistry.

[36]  Jongmin Shim,et al.  Buckling-induced encapsulation of structured elastic shells under pressure , 2012, Proceedings of the National Academy of Sciences.

[37]  J. Lewis,et al.  Printing soft matter in three dimensions , 2016, Nature.

[38]  Zhigang Suo,et al.  Ionic skin , 2014, Advanced materials.

[39]  D. Rus,et al.  Design, fabrication and control of soft robots , 2015, Nature.

[40]  G. Whitesides,et al.  Elastomeric Origami: Programmable Paper‐Elastomer Composites as Pneumatic Actuators , 2012 .

[41]  R D Sochol,et al.  3D printed microfluidic circuitry via multijet-based additive manufacturing. , 2016, Lab on a chip.

[42]  Alain Delchambre,et al.  Towards flexible medical instruments: Review of flexible fluidic actuators , 2009 .

[43]  R. Adam Bilodeau,et al.  Monolithic fabrication of sensors and actuators in a soft robotic gripper , 2015, 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS).

[44]  Robert J. Wood,et al.  Soft robotic glove for combined assistance and at-home rehabilitation , 2015, Robotics Auton. Syst..

[45]  Robert J. Wood,et al.  Simple passive valves for addressable pneumatic actuation , 2014, 2014 IEEE International Conference on Robotics and Automation (ICRA).