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Members of the Keplinger Research Group. From right: Assistant Professor Christoph Keplinger, graduate student Eric Acome, undergraduate student Madison Emmett, graduate student Nick Kellaris, graduate student VC Gopaluni Venkata, undergraduate student Madeline King, graduate student Shane Mitchell, PhD candidate Timothy Morrissey and undergraduate student Garrett Smith. Photo by Glenn Asakawa / University of Colorado Boulder.

When we picture robots, “soft” is not typically the word that comes to mind; the industrial world is littered with rigid, metallic machines.

Biology, however, typically utilizes soft structures. Our muscles, for instance, are highly adaptable soft actuators which provide a range of different movements while effectively interacting with their environment. Soft robotics is a burgeoning field that strives to mimic the functionality of the natural world to create machines that more fluently perform dynamic and unstructured tasks while seamlessly interacting with humans.

In the in the College of Engineering and Applied Science, we recently introduced a new type of artificial muscle that has potential to transform the field of soft robotics, as featured in Science and Science Robotics. The development of these muscles is the culmination of two years of interdisciplinary work from a young team of graduate and undergraduate researchers, led by Christoph Keplinger.

Within our group we try to practice frugal science, or the use of inexpensive materials and methods. This self-imposed constraint combined with our group’s collaborative spirit often leads to simple and unexpected solutions. For example, our artificial muscles can be made from a variety of materials, and the list of ingredients sounds like a mix of chemistry supplies and groceries: silicone rubber, conductive gels, vegetable oil and plastic used for potato chip bags. Using inexpensive materials is important for us to quickly try new ideas and ensures that the technology is more accessible to a broad audience.

In developing these new soft actuators, we relied heavily on the collective knowledge and creativity of our team members. Understanding what materials to use, how to fabricate them and how to operate the actuators requires a diverse set of skills. Luckily, our research group is filled with people from different backgrounds including physics, mechatronics, materials science and mechanical engineering. We also work with a number of undergraduates in our lab; their perspectives provide a fresh viewpoint and creative ideas. Undergraduate researchers are also great at asking questions, which forces us to reflect carefully on our work. Relying on multiple backgrounds, skill sets and perspectives has been critical for the success of our recent publications in and . However, we are looking to collaborations outside the lab as we further develop this technology.

Integrating our soft actuators into robotic systems will require the skills and knowledge of experts in controls, materials science, electronics, theoretical mechanics and computer science. Research challenges like this highlight the importance of new programs like the College of Engineering and Applied Science’s Interdisciplinary Research Themes. Soft robotics fall under one area of the Multi-Functional Materials research theme, which focuses on “materials that mimic the tight integration of sensing, actuation and computation of biological systems closer than ever.”

Our research group has already begun collaborating with groups in the research theme to develop a synthetic tissue to improve practice and testing of medical procedures. Collaborations like this have us excited about the bright future for research in soft robotics at CU Boulder.

Eric Acome, Nick Kellaris and Shane K. Mitchell are PhD students in the College of Engineering and Applied Science at CU Boulder. Eric and Nick were the first authors of the Science and Science Robotics papers, respectively, while Shane was a co-author of both papers.