Public Release: 

Actuators inspired by muscle

The new actuators could pave the way for entirely soft-bodied robots that are safer than their conventional rigid counterparts

Wyss Institute for Biologically Inspired Engineering at Harvard

(CAMBRIDGE, Massachusetts) - To make robots more cooperative and have them perform tasks in close proximity to humans, they must be softer and safer. A new actuator developed by a team led by George Whitesides, Ph.D. - who is a Core Faculty member at Harvard's Wyss Institute for Biologically Inspired Engineering and the Woodford L. and Ann A. Flowers University Professor of Chemistry and Chemical Biology in Harvard University's Faculty of Arts and Sciences (FAS) - generates movements similar to those of skeletal muscles using vacuum power to automate soft, rubber beams.

Like real muscles, the actuators are soft, shock absorbing, and pose no danger to their environment or humans working collaboratively alongside them or the potential future robots equipped with them. The work was reported June 1 in the journal Advanced Materials Technologies.

"Functionally, our actuator models the human bicep muscle," said Whitesides, who is also a Director of the Kavli Institute for Bionano Science and Technology at Harvard University. "There are other soft actuators that have been developed, but this one is most similar to muscle in terms of response time and efficiency."

Whitesides' team took an unconventional approach to its design, relying on vacuum to decrease the actuator's volume and cause it to buckle. While conventional engineering would consider bucking to be a mechanical instability and a point of failure, in this case the team leveraged this instability to develop VAMPs (vacuum-actuated muscle-inspired pneumatic structures). Whereas previous soft actuators rely on pressurized systems that expand in volume, VAMPs mimic true muscle because they contract, which makes them an attractive candidate for use in confined spaces and for a variety of purposes.

The actuator - comprising soft rubber or 'elastomeric' beams - is filled with small, hollow chambers of air like a honeycomb. By applying vacuum the chambers collapse and the entire actuator contracts, generating movement. The internal honeycomb structure can be custom tailored to enable linear, twisting, bending, or combinatorial motions.

"Having VAMPs built of soft elastomers would make it much easier to automate a robot that could be used to help humans in the service industry," said the study's first author Dian Yang, who was a graduate researcher pursuing his Ph.D. in Engineering Sciences at Harvard during the time of the work, and is now a Postdoctoral Researcher.

The team envisions that robots built with VAMPs could be used to assist the disabled or elderly, to serve food, deliver goods, and perform other tasks related to the service industry. What's more, soft robots could make industrial production lines safer, faster, and quality control easier to manage by enabling human operators to work in the same space.

Although a complex control system has not yet been developed for VAMPs, this type of actuation is easy to control due to its simplicity: when vacuum is applied, VAMPs will contract. They could be used as part of a tethered or untethered system depending on environmental or performance needs. Additionally, VAMPs are designed to prevent failure - even when damaged with a 2mm hole, the team showed that VAMPs will still function. In the event that major damage is caused to the system, it fails safely.

"It can't explode, so it's intrinsically safe," said Whitesides.

Whereas other actuators powered by electricity or combustion could cause damage to humans or their surroundings, loss of vacuum pressure in VAMPs would simply render the actuator motionless.

"These self-healing, bioinspired actuators bring us another step closer to being able to build entirely soft-bodied robots, which may help to bridge the gap between humans and robots and open entirely new application areas in medicine and beyond," said Wyss Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Boston Children's Hospital Vascular Biology Program, as well as Professor of Bioengineering at Harvard's John A. Paulson School of Engineering and Applied Sciences (SEAS).

Harvard's Office of Technology Development has filed patents on this and related inventions, and the soft actuator technology has been licensed to Soft Robotics, Inc., a startup launched in 2013 and cofounded by Whitesides. The company is developing robotic grasping systems toward initial applications including picking and packing in unstructured environments--for example, handling fruits and vegetables in produce distribution warehouses. Longer term, this technology can be leveraged to develop products for biomedical applications.

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In addition to Whitesides and Yang, other authors on the study included: Mohit S. Verma, Ph.D.,(FAS); Ju-Hee So, Ph.D., (FAS); Bobak Mosadegh, Ph.D., (Wyss, FAS); Christoph Keplinger, Ph.D., (FAS); Benjamin Lee (FAS); Fatemeh Khashai (FAS); Elton Lossner (FAS), and Zhigang Suo, Ph.D., (SEAS, Kavli Institute).

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Wyss Institute for Biologically Inspired Engineering at Harvard University?
Kat J. McAlpine, katherine.mcalpine@wyss.harvard.edu, +1 617-432-8266

Harvard Faculty of Arts and Sciences
Peter Reuell, preuell@fas.harvard.edu, +1 617-496-8070

Harvard John A. Paulson School of Engineering and Applied Sciences?
Leah Burrows, lburrows@seas.harvard.edu, +1 617-496-1351

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Wyss Institute for Biologically Inspired Engineering at Harvard University?
Seth Kroll, seth.kroll@wyss.harvard.edu, +1 617-432-7758

The Wyss Institute for Biologically Inspired Engineering at Harvard University uses Nature's design principles to develop bioinspired materials and devices that will transform medicine and create a more sustainable world. Wyss researchers are developing innovative new engineering solutions for healthcare, energy, architecture, robotics, and manufacturing that are translated into commercial products and therapies through collaborations with clinical investigators, corporate alliances, and formation of new startups. The Wyss Institute creates transformative technological breakthroughs by engaging in high risk research, and crosses disciplinary and institutional barriers, working as an alliance that includes Harvard's Schools of Medicine, Engineering, Arts & Sciences and Design, and in partnership with Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Boston Children's Hospital, Dana-Farber Cancer Institute, Massachusetts General Hospital, the University of Massachusetts Medical School, Spaulding Rehabilitation Hospital, Boston University, Tufts University, Charité - Universitätsmedizin Berlin, University of Zurich and Massachusetts Institute of Technology.

Harvard University Faculty Arts and Sciences (FAS), founded in 1890, is the largest division of Harvard University. The Faculty of Arts and Sciences is dedicated to being at the forefront of teaching and learning and fostering cutting edge research and discovery. FAS is redefining liberal arts education for the 21st century and is committed to an open Harvard and student aid by making a Harvard education accessible to students from all backgrounds. FAS comprises Harvard College and the Graduate School of Arts and Sciences, including undergraduate and graduate admissions; the School of Engineering and Applied Sciences; and the Division of Continuing Education, including the Extension and Summer Schools. FAS also encompasses academic resources, such as libraries and museums, as well as campus resources and athletics.

The Harvard John A. Paulson School of Engineering and Applied Sciences serves as the connector and integrator of Harvard's teaching and research efforts in engineering, applied sciences, and technology. Through collaboration with researchers from all parts of Harvard, other universities, and corporate and foundational partners, we bring discovery and innovation directly to bear on improving human life and society.

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