A prosthetic hand that researchers say is lighter and cheaper than the alternatives has been developed by a team at the University of Malta.
The MAProHand, which has already been created into a workable prototype, was developed to try to create a limb that would be less likely to be rejected by a wearer due to being too heavy.
Speaking to Times of Malta, engineering Prof. Michael Saliba said that development of the innovative device came on the back of two principles discovered by the research team.
Firstly, when a person loses a hand, the remaining hand becomes the dominant hand, irrespective of whether it had occupied this role before, he explained. This means the role of the prosthetic could be developed with the intention of it being the non-dominant hand and therefore could afford to be less complex.
Secondly, following research with users, the department concluded that some basic tasks, such as grasping or supporting objects, can still be carried out effectively by using only three digits (the thumb, the index and the middle fingers) while retaining a high level of dexterity. This also meant that the design of the prosthetic could be simplified even further.
“In theory, every motion made by a prosthetic requires its own motor, so the most complex prosthetic with five-finger movement would require it to have five motors,” Saliba said. “This in turn makes the prosthetic quite heavy, which often leads to a high number of users rejecting it because of the discomfort that the weight causes.”
While the average human hand weighs around 400 grams, as a prosthetic is not connected to the body through a bone but only through the surrounding tissue, even a device that weighs a baseline 400 grams can feel too heavy for a user, he explained.
Because it is effectively only moving three digits, the MAProHand only requires three motors to work while allowing users the full range of motions of a non-dominant hand. Along with its 3D-printed body, this gives the prosthetic an edge in cutting down the weight of the device.
“Currently, our prototype weighs in at just under 400 grams, but with further development, we believe we can get it down to 300 grams,” Saliba said.
Amputees happy with design
He added that amputees who worked with researchers to test the software that runs the prosthetic seemed happy with the design and quickly picked up how to use it.
“When we brought in volunteers who’ve had an amputation to test it out they were able to see how the prosthetic would function in a simulation, for the large part they were happy with the results and found that it responded to what they wanted it to do quite accurately,” he said.
“From the simulation runs, we found that it had a 90 per cent reliability rate, which means that the hand was able to perform the task correctly on the first try 90 per cent of the time.”
The project started with undergraduate students who researched the motion and dexterity required of a prosthesis to mimic hand movements, and in collaboration with the Orthopaedic Centre evolved into the production of a workable prototype.
As researchers are looking to patent and further develop the prosthetic, which was funded under the National Fusion Research and Innovation Programme through the Malta Council for Science and Technology, Saliba thinks it could be a game-changer in the prosthetic market.
“I think it could have an impact because it will make another option available for amputees, a dextrous hand that is not only cheaper, but simpler and lighter than others,” he said.
“For many people making the choice to wear a hand or not, we want to introduce the option of having a hand that is not just for aesthetic purposes at a more achievable cost.”