Jacob Segil shows Kassie Van Pelt, HR coordinator with CU’s Department of Mechanical Engineering, how the sensors work. (photo by Joe Harrison)

Feels Like Progress

By Sara Bruskin

Modern prosthetic arms and hooks are highly functional, and the people who use them have little to no problem with everyday tasks (after an adjustment period, of course). The phantom limb sensation, however, still causes severe physical dissonance for many amputees, regardless of prosthetic use. People experience ghostly sensations from an arm that’s no longer there, and those sensations frequently climb to intense pain.

Engineers who work on prosthetics are hoping to increase functionality and relieve some of that bodily dissonance by manufacturing arms that can convey a sense of touch to the wearer. Jacob Segil, an instructor at the University of Colorado Boulder and research healthcare scientist in the Rocky Mountain Regional VA Medical Center, is leading a team developing fingertip sensors for prosthetics that can “feel” tactile pressure. People using this technology will be able to interpret the hardness or softness of an object they’re touching, and feel how tightly they’re gripping it.

A prototype prosthetic hand with the fingertip sensors built by Jacob Segil and his team at CU. (photo by Jacob Segil)

This information can be conveyed to the brain through technology being developed at Case Western Reserve University’s Functional Neural Interface Lab in Cleveland. Dustin Tyler, whose team has partnered with Segil’s, is developing prosthetics that connect to electrodes surgically embedded in the arm, in close proximity to nerve bundles. The nerves interpret the electrodes’ electric signals as sensory information, and relay it to the brain.

With the combined efforts of faculty and graduate students like Nikolaus Correll, Richard Weir and Radhen Patel, Segil’s team has already accomplished the initial goal of creating fingertip sensors that work for this purpose…in the sheltered environment of a lab. Now, they face the challenge of making their sensors rugged enough for everyday use. Segil says, “We beat up our hands and bodies regularly, and we need our sensors to work as well on day one as they work on day 365.”

Making the fingertip pads sensitive enough to register minute differences in pressure, yet sturdy enough to handle adventures in the real world is no simple feat, but Segil’s team has been met with a groundswell of support. Their initial research was funded by a seed grant from the College of Engineering’s Multi-functional Materials Interdisciplinary Research Theme. The U.S. Department of Veteran Affairs recently awarded the team a $200,000 contract to create 25 prototypes for further testing by the end of 2019.

The team has a complicated research and development puzzle ahead of them, but Segil says he’s excited to face it. “The body is the most elegant machine that’s ever been, and it’s a great challenge to re-create it.”