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.
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Now, at the University of Science and Technology of China and his colleagues have developed a voice-controlled prosthetic hand that weighs just 220 grams 鈥� about half the weight of a typical human hand, but it can move in nearly as many directions.
To move its fingers and joints, the hand uses a shape memory alloy, a metal that changes shape when heated and then returns to its original form when it cools. 鈥淭he shape memory actuators mimic the function of human muscles, enabling finger and wrist movements,鈥� says Zhang. 鈥淭he prosthetic hand also employs a closed-loop control system that senses joint angles in real-time, facilitating precise and coordinated movements.鈥�
This alloy helps the hand鈥檚 fingers to move in more complex ways, such as spreading fingers apart, which means they can do intricate movements that other prosthetic hands struggle with, like opening an elastic band with three fingers or manipulating a piece of string.
A woman with a right arm amputation trialled the prosthetic over five hours and was able to carry out tasks like writing, playing chess and combing her hair, without reporting discomfort.
鈥淥ne of the main criticisms of prosthetic hands is how weighty and heavy they are and [the researchers have] managed to reduce the weight of their hand, which is great,鈥� says at the University of Southampton, UK. However, the voice-activation system might not suit prosthetics-wearers who don鈥檛 want to stand out in public environments, she says: 鈥淚t鈥檚 great if it works, but is it great if you鈥檙e just wanting to blend in?鈥�
Nature Communications
