Prosthetics Breakthrough: Robot Arm Lets User Feel Touch Again

All thanks to research conducted by a team of biomedical engineers at the University of Utah, Keven Walgamott, an amputee of 17 years, can now wear his wedding ring with the help of  his brand new prosthetic hand. 

The prototype is called the Luke Arm, named after the robotic hand used by Luke Skywalker in The Empire Strikes Back. The device comes closest to mimicking the way the human hand functions as it has sensory perception, enough to feel different surfaces and be controlled by his brain. 

Amputees will be able to perform a number of complex tasks, much more than is possible with a prosthetic that provides metal hooks and claws to navigate the world. Walgamott, a real estate agent, was brought to tears when he experimented with the Luke Arm in clinical trials in 2017. “It was really amazing. I never thought I would be able to feel in that hand again,” he said in a press release issued by the University. 

He was one of seven participants who had tried the product on. He was successfully able to pluck out a group of grapes without squishing them, pick up an egg without breaking it and even feel his wife’s hand as a result. Apart from this prototype, they have already developed another prototype of a portable prosthetic hand that need not to be connected to a computer.  

The paper titled, "Biomimetic sensory feedback through peripheral nerve stimulation improves dexterous use of a bionic hand," detailing this innovation was published in the journal Science Robotics on July 24. The authors are doctoral student Jacob George, associate professor Gregory Clarke and former doctoral student David Kluger, among others in the biomedical department. 

How did this work?

The prosthetic arm works through an external battery, while being wired to a computer. Metal motors and silicon skin make up the arm for the most part. Nerves in the human arm are connected to 100 microelectrodes and wires through a system called Utah Slanted Electrode Array developed by Professor Richard A Normann. 

This array receives and interprets impulses from the remaining nerves that were not amputated in the recipient's hand. A computer converts them into digital signals that can control the arm’s movement. The DEKA Research & Development Corp. was the company behind the battery.

The biggest challenge was recreating the burst of impulses when the hand comes into contact with an object at first that recedes by itself. This is important to adjust the pressure and move it between the fingers while feeling the object and sending a signal to the brain is not enough to achieve this. It’s a lot of sensory perception involved but was achieved nonetheless. 

Greg-Clark-LUKE-Arm Doctoral student Jacob George and Associate professor Gregory Clark came up with the prosthetic hand capable of moving according to signals received by the brain. Dan Hixson/University of Utah College of Engineering.