The importance of wearable devices increases steadily as they can provide realtime physical feedback, posses versatile functionality, and the best of all, a decent comfort to the wearer. While different kinds of actuators, such as motor driven tendon, pneumatics, and electromagnetic, t were applied to wearable devices, they all require rigid and bulky system attached to the wearer which can cause discomfort. Shape memory alloy (SMA) that can change its physical shape and stiffness by temperature change can be used as a wearable actuator, especially when SMA wires are processed into fabrics. Here, we developed SMA fabric which was prepared by knotting the SMA wires and expanding them into 2D fabrics. Also, the knotted SMA fabric was designed to have auxetic property which can dedicate to increasing compliance of wearable SMA fabric to the 3D-curved human body. Knotted auxetic-SMA fabric was successfully applied as a wearable haptic to deliver thermomechanical feedback to the wearer.

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Sae-Woong Oh and Il-Kwon Oh, "Knotted auxetic-SMA fabric for wearable haptic (Conference Presentation)," Proc. SPIE PC12485, Nano-, Bio-, Info-Tech Sensors, and Wearable Systems 2023, PC1248503 (Presented at SPIE Smart Structures + Nondestructive Evaluation: March 13, 2023; Published: 18 April 2023); https://doi.org/10.1117/12.2659287.6323732622112.