Development of a biomimetic transradial prosthetic arm with shape memory alloy muscle wires

This paper presents a first concept of a new biomimetic transradial prosthetic arm design, called 'MataPro-1,' that features a 3D-printed hand bone structure that mimics the shape of human finger phalanges and palm bones, flexible elastic joints, artificial muscles, and silicone flesh that covers and protects the internal components, provides restoring force, enables better gripping capability, and appears cosmetically realistic. The artificial muscles that actuate MataPro-1 are shape memory alloy (SMA) wires, which ensure effective grip strength for many everyday objects, without causing any noise. In order to avoid the need to cool SMA wires in the small volume of the fingers, the SMA wires are not routed through the finger phalanges. The SMA wires are spooled in the forearm, cooled by a fan only during the finger restoration process, and are connected to steel wires that are routed through the finger phalanges. The finger restoring force provided by the flexible joints and silicone flesh acts as bias force for SMA wires, avoids the need for antagonistic SMA wires, and speeds up the finger restoration process. The control system of MataPro-1 is intuitive and non-invasive achieved by voice recognition phone application, or an EEG headset that monitors brainwaves and facial expressions. MataPro-1 was successful in gripping different objects of various shapes, weights and sizes in multiple different gripping positions.