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Lab testing haptics device in prosthetic hands to help users with grip

Haptics lab at Johns Hopkins University
Posted at 7:32 PM, Sep 14, 2021

In a room inside Dankmeyer Prosthetics and Orthotics, employees are making and modifying prosthetic limbs for those who need them.

“We’re the interface between the patient and getting their device managed. And we do mostly custom work,” Mark Hopkins, co-owner of Dankmeyer Prosthetics and Orthotics, said. “Everything we do is a compromise, and we know that. And just to be simplistic about it we’re always looking to build a better mousetrap.”

There are many different types of prostheses. Though the technology is getting better, Hopkins said they regularly face new challenges.

“The more the client has to think about what they're doing with the device, the less they can do of other things,” Hopkins said.

“The more feedback the user of the hand gets, the better they’re going to be able to use it,” Andrew Rubin said. He is one of Hopkins’ clients and has both a prosthetic leg and hand.

“This isn't a hand, right? It’s just a device and I would really like the research to get to a place where it begins to think of the hand as a smart hand, a hand that can do things without me necessarily thinking about doing it,” he said.

“We know that some of the advanced designs we’re developing reduce the cognitive load, which makes us optimistic,” Hopkins said.

It’s something Jeremy Brown and his lab at Johns Hopkins University has been working on advancing.

“Right now most commercial prostheses do not allow an amputee to feel with their prosthetic limb,” Jeremy Brown with the Haptics and Medical Robotics Laboratory at Johns Hopkins University, said. “Really we’re looking at the application of haptic feedback in prosthetics.”

“It’s sort of hard, I think, to understand what life without touch is,” he said.

Processes like holding something delicate are more difficult for those with prosthetic limbs. “Pick up an object like an egg without being concerned that if you squeeze to hard you might break it,” Brown explained.

In the lab, they are using a test device that provides vibration feedback to let the user know when they are squeezing too tight, or not enough.

“We all have kind of experienced viral tactile feedback with consumer electronic cell phones. Anytime your phone vibrates to let you know someones calling you or texting you, that’s just the vibration cue and that's essentially what we’re using in our lab for research purposes. And what we're doing is tying the intensity of that how much force you’re squeezing with on the prosthesis,” Brown explained.

Rubin says he can see how this tech can help with sensation. “I can see it’s terms of refining my ability to control things,” he said.

These devices are getting more advanced as more technologies are integrated -- from haptics to Bluetooth to 3D printing. Brown hopes to soon have more participants to test haptic feedback.

“My hope is that this research eventually leads to future prosthetic devices that function the same way our natural limbs do,” Brown said.

“There are a lot of people in the world that have missing limbs...if they are limited in their recovery from their disease or trauma or unable to get to functional independence or good quality of life, we’re just missing out all these people could be contributing, and for me, that’s the bigger picture,” Hopkins said.