Yale's Robotic Fabric Can Stiffen, Move, Sense Its Environment, and Even Save Lives as a Tourniquet
The multi-function robotic fabric is described as a "breakthrough," and can switch from rubber-like flexibility to acrylic hardness.
Researchers at the Yale School of Engineering and Applied Science have developed a "robotic fabric" capable of actuation, sensing, and variable stiffness — and say it represents a breakthrough in soft robotics.
"Fabrics are key materials for a variety of applications that require flexibility, breathability, small storage footprint, and low weight," the researchers explain. "While fabrics are conventionally passive materials with static properties, emerging technologies have provided many flexible materials that can respond to external stimuli for actuation, structural control, and sensing."
"Here, we improve upon and process these responsive materials into functional fibers that we integrate into everyday fabrics and demonstrate as fabric-based robots that move, support loads, and allow closed-loop controls, all while retaining the desirable qualities of fabric. Robotic fabrics present a means to create smart adaptable clothing, self-deployable shelters, and lightweight shape-changing machinery."
The robotic material created by the team includes actuation capabilities, sensory capabilities, and can adjust its fibers into various stiffnesses — while retaining the flexibility and breathability of fabric. The secret: Field's metal, an alloy which is liquid at relatively low temperatures.
"Our Field’s metal-epoxy composite can become as flexible as latex rubber or as stiff as hard acrylic, over 1,000 times more rigid, just by heating it up or cooling it down," writes lead author Trevor Buckner. "Long fibers of this material can be sewn onto a fabric to give it a supportive skeleton that we can turn on and off."
The sensors, meanwhile, are driven on a conductive ink known based on a Pickering emulsion. "The conductive composite self-coagulates around the individual fibers and does not notably change the porosity of the fabric,” Assistant Professor Rebecca Kramer-Bottiglio notes. "The sensors are visible, but don’t change the texture or breathability of the fabric, which is important for comfort in wearable applications."
Actuation, meanwhile, is driven by shame-memory alloy (SMA) wires, but not in the usual coil or mesh format found in soft robotics. "Instead of using the coil technique," Buckner adds, "we flattened the wires out into ribbons to give them a geometry much more suited to smooth bending motion, which is perfect for robotic fabrics."
The team demonstrated the material being used in a shape-changing soft robot, a load-bearing fabric structure, a wearable robotic tourniquet, and an airplane with stowable and deployable fabric wings in a paper published under closed-access terms in the Proceedings of the National Academy of Sciences.