Image Courtesy of the Kramer Lab.
The word “robot” typically conjures images of cold metal machines or stark white droids. However, not all robots fit that mold—some are composed of more flexible materials such as robotic fabrics, which combine textiles with advanced robotics. Robotic fabrics allow robots to twist, fold, and change shape to adapt to different tasks and environments, including capabilities that were once off-limits to metal robots.
Recently, a team of researchers led by Rebecca Kramer-Bottiglio, an associate professor of Mechanical Engineering and Materials Science at Yale, has developed a new type of robotic fabric that is both flexible and functional. Previous robotic fabrics have all been limited in their applications because they are “passively-rigid,” meaning they remain rigid without an external power source, limiting their applications. On the other hand, this new fabric is “passively-flexible”—it acts as a fabric without stimulation and stiffens when activated, allowing it to move and support its own weight like a small, soft robotic creature.
The process of creating this robotic fabric begins with laser cutting extremely thin sheets of a material called nitinol into precise beams. Nitinol, a shape-memory alloy, exhibits a special property—it can be deformed when cooled to low temperatures but made to return to a specific shape when heated. The resulting structures can be bent or straightened with electrical stimulation. When these beams are attached to a piece of fabric, electrically stimulated changes in geometry yield variable stiffness in the fabric. By strategically placing tiny actuators along this material, Kramer-Bottiglio and her team designed a fabric-based robot that could make simple but impressive movements.
Kramer-Bottiglio’s fabric robot prototype serves as an important proof-of-concept, demonstrating the potential of robotic fabrics. First, her robots are quite flexible—the fabric can bend up and down or twist side to side, enhancing its maneuverability. In tests, the fabric was also able to crawl by inching forward. Additionally, these robotic fabrics are untethered: they carry their own power supply and are thus not restricted by a cable connection to a stationary source. Finally, this robotic fabric maintains its functionality while also being incredibly lightweight—it weighs just 30.9 grams, including its self-supported battery. This property is ideal for creating wearable technology and other soft robotics that require flexibility and compactness.While this new robotic fabric shows promise, it still faces challenges—particularly regarding energy efficiency and heat management. Kramer-Bottiglio plans to improve upon this work by exploring ways to monitor and prevent overheating on certain components of the robot and to modify the design to increase speed and efficiency. These future improvements could make robotic fabrics suitable for more complex tasks. In the study, the researchers describe a vision for robotic fabrics capable of transforming into various shapes within the same structure. For instance, they could waltz across rough terrain on four legs, and then seamlessly transform into a pincer to move an object. As Kramer-Bottiglio and other researchers in the field continue to build upon innovative fabric design, we may soon see robotic fabrics applied in a wide breadth of settings. Kramer-Bottiglio described this possible impact in an interview with Yale for Humanity. “The possible application areas are vast and varied—wearables, agriculture, medicine, and potential assistive robots to help people with a variety of conditions, including aging. Adapting to unexpected impacts and varied terrains also positions future soft robots as exemplary exploratory vessels,” Kramer-Bottiglio said.