An inexpensive prosthetic arm has been developed that provides the wearer with tactile control [video]
Engineers from MIT and Shanghai Jiao Tong University have developed a prosthetic hand that accurately flexes individual fingers to grasp objects and also provides the user with tactile feedback.
According to MIT, there are more than five million upper arm amputations worldwide each year, and while many amputees have to settle for static prostheses, recent advances in articulated "robotic" prostheses and sensory feedback have made commercially available devices that can take residual muscle signals and convert them into arm movements. However, such technology can often be heavy and expensive.
The soft prosthetic, created by a team of engineers from MIT and Shanghai Jiao Tong University, weighs about 225g and the total cost of the components is about $500, making it potentially more affordable as well as easier to use.
The fingers in the new system are made from a commercially available soft and elastic elastomer called EcoFlex with bone-like fiber segments embedded in it. They are attached to a 3D printed support in the shape of a human palm.
Instead of installing motors to control each finger module, MIT's setup uses a small pump and valves at the user's waist (to reduce the weight of the prosthesis itself) to apply pressure to the fingers, giving them a specific shape. This pneumatic system is controlled by EMG sensors attached to the user's limb.
Using computer simulations, the researchers developed a controller that allows them to use muscle signals picked up by the sensors to inflate the fingers so that they reproduce five common grasping actions, including pinching, clenching into a fist and squeezing the palm. The team also embedded a pressure sensor in each fingertip and then connected them all to specific areas on the user's stump to provide real-time tactile feedback.