Scientists at ETH Zurich in Switzerland have developed a hand exoskeleton (外骨骼) to help people regain their grip after a stroke (中风). Powered by motors, the exoskeleton has strong and flexible stainless steel springs (不锈钢弹簧). An accordion-like (类似手风琴的) part helps the spring change straight movement into a grip force, allowing it to bend and stretch. Weighing just 270 grams, about the same as a phone, it’s made from 3D-printed nylon and is comfortable to wear.