ECE students involved in work on prosthetic hand with sensory feedback
Cheap and functional prosthetics are hard to come by for the majority of amputees, but several Illinois students are working to change that.
A team of graduate and undergraduate students in CSL and Aerospace Associate Professor Timothy Bretl’s lab are working on developing an affordable prosthetic hand that can return both motor and sensory functions to its user. The goal of the project being that eventually these hands can be distributed to people with amputations in impoverished regions who can’t afford rehabilitative care. Bretl is an ECE affiliate.
Akhtar had been doing work with the Rehabilitation Institute of Chicago, where they have expensive state-of-the-art prosthetic hands, but wanted something more easily accessible with which he could incorporate his research. Then, a little luck came his way.
“Completely serendipitously, an undergraduate student in Mechanical Science & Engineering, Patrick Slade, emailed me a week later, not knowing that we had started this project,” Akhtar said. “He had 3-D-printed his own prosthetic hand in high school, and he wanted to know if we had any use for it. And we definitely had a use for it. We incorporated our neural signal control for the hand and we were able to control the fingers just based off of muscle activity.”
Akhtar decided to pursue the project and established a team composed of Nguyen, Slade, undergraduate ECE students Michael Fatina, Sam Goldfinger, Alvin Wu, and Edward Wu, and undergraduate bioengineering student Joe Sombeck. Slade is still involved, as well. The ECE students received some independent study funding for the project from the ECE annual fund.
The team aims to give people with upper limb amputations a working hand for everyday use. One way they are doing that is by attempting to create a way for the hand to contract into various grips that can be controlled by the muscle movement of the user. They accomplish this through electromyography, which sends voltages from intact muscles into the prosthetic hand to allow it to contract into various grips.
“When a patient thinks of controlling his phantom hand, and he says, ‘I want to close it,’ their residual muscles will still contract,” Fatina said. “The electrodes will pick that up. So you can move the hand into a fist or a pointer finger extended. Those are just two of them. The longer you try to do the grip, the further the hand closes. Then you can also open the hand as well.”
A major issue for amputees is that they have lost their ability for proprioception, which means that the user of the prosthetic hand wouldn’t know what position his hand was in when not looking directly at it. This is a common reason why people with amputations abandon their prosthetics.
Akhtar and Nguyen have developed a skin stretch feedback system, which they hope will solve the problem of proprioception. The skin stretch method involves attaching a string to the fingers on one end and contact pads attached to the skin on the other end. So when the hand is being contracted into different grips, the user should know where the hand is despite not looking directly at it. According to Akhtar, skin stretch has had 80 percent success rate with amputees. Akhtar has also been working on the use of electrical stimulation to provide touch and force feedback to the user.
Eventually, Akhtar hopes to make a startup out of this project, but the team still sees themselves about a year away from having a finished product. He said they are already working on making the fingers and mechanical design better as well as making the hand smaller than it already is.
Despite not having a finished product, they have already found a way to put the hand to use through the Range of Motion Project (ROMP). This organization was started by Illinois alumnus David Krupa to provide prosthetics to amputees in underdeveloped countries. When Akhtar approached Krupa with his project, the two hit it off and decided to collaborate.
After their meeting at the end of the spring semester, the team worked through the summer to produce a hand they could test on amputees in Ecuador.
“We had just been iterating and iterating, just trying to get all of the electronic, mechanical, and software aspects of this to work,” Akhtar said. “In the last two week of the summer, Mary and I took this hand down to Ecuador and had a patient use it and they were actually able to control it with their own residual muscles. That was really awesome.”