Prosthetics technology has been advancing rapidly of late, with a number of breakthroughs or emerging technologies that will help those with artificial limbs feel sensations such as pressure and heat and, as a result, move more naturally with more exact dexterity. Grasping a small item such as a cup of coffee, for example, would be much easier if there were a two-way interface between brain and fingers.
The Department of Defense has such high hopes for the technology that they’ve granted researchers at Dallas’ Southern Methodist University’s Lyle School of engineering $5.6 million to create a research facility to work on lightning-fast connections between robotic limbs and the human brain for injured soldiers and other amputees.
The key, researchers believe, is light. More specifically, fiber optic links that would send signals seamlessly back and forth between the brain and artificial limbs.
“Currently available prosthetic devices commonly rely on cables to connect them to other parts of the body for operation—for example, requiring an amputee to clench a healthy muscle in the chest to manipulate a prosthetic hand. The movement is typically deliberate, cumbersome, and far from lifelike,” according to SMU. “The goal of the Neurophotonics Research Center is to develop a link compatible with living tissue that will connect powerful computer technologies to the human nervous system through hundreds or even thousands of sensors embedded in a single fiber.”
Every movement or sensation a human being is capable of has a nerve signal at its root. "The reason we feel heat is because a nerve is stimulated, telling the brain there's heat there," Marc Christensen, center director and electrical engineering chair in SMU's Lyle School of Engineering said in a report on the new technology.
Unlike experimental electronic nerve interfaces made of metal, fiber optic technology would not be rejected or destroyed by the body's immune system.
The center formed around a challenge from the industrial partners to build a fiber optic sensor scaled for individual nerve signals: "Team members have been developing the individual pieces of the solution over the past few years, but with this new federal funding we are able to push the technology forward into an integrated system that works at the cellular level," Christensen said.
Stanford University researchers in Menlo Park recently published the results of their work on creating artificial electronic skin that would be flexible and sensitive to even minor touches, such as the weight of an insect. Such a touch-sensitive material could be used for human prosthetics, sensory input devices for robotics, and applications where the biologic and electronic communicate, according to the report. That project is supported by the Department of Energy.
Researchers placed a thin sheet of rubber between even slimmer electrodes to make flexible and (you guessed it) thin pressure sensors. To make the rubber sheet more spongy and pressure-sensitive, millions of little structures were molded into it. As the rubber film deforms on exertion of pressure, the electrodes change proximity resulting in a change of charge that can register as “feeling.” The researchers found their material to be sensitive enough to detect a fly and fast enough to provide fluid reaction times when perceived by people.
What’s next?
Researchers from SMU, Vanderbilt University, Case Western Reserve University, the University of Texas at Dallas, and the University of North Texas are also investigating the possibilities of man-to-machine applications that extend far beyond prosthetics, leading to medical breakthroughs such as brain implants for the control of tremors, neuro-modulators for chronic pain management, and implants for patients with spinal cord injuries. "This technology has the potential to patch the spinal cord above and below a spinal injury," Christensen said. "Someday, we will get there."