Active fabrics with controllable stiffness for robotic assistive interfaces

Abstract

Assistive interfaces enable collaborative interactions between humans and robots. In contrast to traditional rigid devices, conformable fabrics with tunable mechanical properties have emerged as compelling alternatives. However, existing assistive fabrics actuated by fluidic or thermal stimuli struggle to adapt to complex body contours and are hindered by challenges such as large volumes after actuation and slow response rates. To overcome these limitations, inspiration is drawn from biological protective organisms combining hard and soft phases, and active assistive fabrics consisting of architectured rigid tiles interconnected with flexible actuated fibers are proposed. Through programmable tessellation of target body shapes into architectured tiles and controlling their interactions by the actuated fibers, the active fabrics can rapidly transition between soft compliant configurations and rigid states conformable to the body (>350 times stiffness change) while minimizing the device volume after actuation. The versatility of these active fabrics is demonstrated as exosuits for tremor suppression and lifting assistance, as body armors for impact mitigation, and integration with electrothermal actuators for smart actuation with convenient folding capabilities. This work offers a practical framework for designing customizable active fabrics with shape adaptivity and controllable stiffness, suitable for applications in wearable exosuits, haptic devices, and medical rehabilitation systems.