In 2019, researchers at the Hiroshima University in Japan developed a 3D printed prosthetic hand that can be a cheaper alternative for doctors and for patients. It is expected that the hand will be able to respond to users’ intentions easily and faster all the while effectively reducing the costs for future prosthetics.

Patients endure enough physical and mental pain and discomfort when experiencing an illness or a life changing accident. Dealing with the added stress of paying for expensive prosthetic limbs does not help with the recuperating process. However, the 3D printed prosthetic created by the Hiroshima team is a much lighter and cheaper option that works just as efficiently.

Current technology on myoelectric prosthetic hands, that implements an operator’s electromyogram (EMG) signals, has been used and tested. To keep development costs down, this technology has been improved and incorporated with 3D printing. However, prototypes have yet to successfully combine the EMG-based multiple finger movement with the expected advanced, fluid movement and mechanics of human motion.

For the 3D printed hand project, the team created a neural network called the Cybernetic Interface instead of using the full EMG method. They fitted electrodes in the sockets of the prosthetic equipment that measured the electrical signals in the nerves of the patient’s skin. These signals are then read via a computer which is then transmitted into movement within 5 milliseconds. The Cybernetic Interface is said to be a well-functioning system as it accurately recognises human finger movement and deciphers it into distinct formations like a hand fist, a handshake or even the movement to pick up a bottle. All the patient must do is think of the movement and then the robotic hand responds accordingly.

The robotic hand was tested on a small sample of amputees who were instructed to perform a variety of daily life simulated tasks using the 3D printed prosthetic. The results showed a 95% accuracy reading in relation to the tasks successfully completed. More complicated tasks had a 93% accuracy reading. The participants were satisfied with the hand’s functionality. However, some did complain that excessive usage of the prosthetic did cause some form of muscle fatigue.

The team is aware of the complaints and are actively looking to make additional changes to the hand to improve its efficiency and make it user-friendly and available for the market.

References:

1. This 3D-Printed Hand Can Play Rock, Paper, Scissors, July 2019, AsianScientist
2. A myoelectric prosthetic hand with muscle synergy–based motion determination and impedance model–based biomimetic control, June 2019, Robotics Science
3. A Global Network Of Passionate Volunteers Using 3D Printing To Give The World A « Helping Hand. » EnablingtheFuture