Dexterous and light prosthetic hand can tie knots and comb hair

A lightweight prosthetic hand that can move almost as freely as a human hand can help wearers carry out intricate tasks, such as tying knots, combing hair and playing chess.

To replicate the dexterity of a human hand, most commercial prosthetics use electric motors or compressed air systems, which can make the system heavy and uncomfortable to wear for too long.