Q&A with Ozgur Sahin
October 13, 2017
Columbia Technology Ventures (CTV) spoke with Ozgur Sahin, Associate Professor of Biological Sciences and Physics, to learn about the powerhouse potential of bacterial spores and their applications in robotics.
CTV: Robotics isn’t your primary area of research—how did you become involved in the field?
OS: That’s right—our research is at the interface of biology and physics. We’re studying bacterial spores, which are dormant organisms with some characteristics that are desirable from a material point of view. They’re very durable and rigid, and they’re biologically compatible in the sense that many of these spores are already present in various environments.
We were studying spores for a biological purpose—to understand how they respond to moisture. Previous research has noted that bacterial spores change shape at different levels of humidity, but we were surprised to find that these changes in size also come with a lot of force, and that they could potentially serve as great actuators. That’s what makes them so interesting from a robotics point of view, and since Columbia is a place where interdisciplinary research is encouraged, it was easy to explore the idea further.
CTV: What are the specific advantages of spore-drive actuators over the traditional ones used in robotics?
OS: Actuators in robotics are basically muscles—they generate force, push, pull, or move something. But unlike our muscles, which elongate and shorten, the actuators used in robotics are hard and inflexible. Engineers often find that they need to make design compromises to adapt actuators to their purposes. The actuation capabilities of these bacterial spores are much closer in nature to real muscles, in that they can elongate and shorten considerably, and they’re very powerful. They pack a lot more energy, too – about a thousand times more than traditional actuators.
CTV: How are you adapting spore-driven actuators for commercial applications?
OS: Our approach is to create materials using these spores—for example, we created a mixture of spores and adhesive that can be painted on a flexible surface, and once the adhesive dries, it creates an actuating film. When the relative humidity changes, the spores respond—they quadruple in length—and the entire material starts to bend. We’ve demonstrated that by pasting spores in equally spaced patterns on both sides of a film, we can trigger a wavelike contraction that mimics muscle contraction and elongation.
In terms of commercial applications, one potentiall use for these actuators in exoskeletons. They don’t add space or weight, they generate force, and no design changes are required to accommodate them. Prosthetics are another possibility—right now, most prosthetic action is accompanied by the sounds of the device’s motors, and to some degree, there’s a privacy aspect, a sensitivity, associated with that. Spore-based actuators could be used in this application with similar performance but far less sound. The expansion and contraction of these spores happens very rapidly, and it’s essentially silent.
Another application we’re excited about is the idea of using these materials as energy harvesters. We’ve done proof of concept demonstrations showing that it’s possible to harvest energy from the process of evaporation using devices that alternately allow and block evaporation. The spores elongate and shorten like a piston, creating a type of oscillatory engine that will keep running as long as there’s water below it and dry air above it.
CTV: How close is bacterial actuation to commercially viability?
OS: Typically, energy technologies have a long path toward commercialization, but we’ve made progress very quickly. There are simple but powerful applications of this concept that could be utilized right now, but on a smaller scale. If you need an actuator that works in a simple way, without electronics, bacterial spores are readily available—just add water.
Columbia Technology Ventures works closely with Columbia researches to commercialize early-stage technology innovations, connecting industry and investment partners with researchers to bring impactful, in-demand robotic technologies to market as quickly as possible. To see Columbia’s Robotics portfolio available for licensing please click here: http://innovation.columbia.edu/robotics
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