Aaron Negrete is a typical 10-year-old boy who is busy with schoolwork and interested in video games, but the challenges he faces are far different from those his schoolmates encounter. Born without arms or legs, Aaron must get creative to accomplish tasks. He uses his head to operate his wheelchair, his mouth to hold pens, and his nose to tap on a computer. But now, with the help of UC Davis robotics engineer Sanjay Joshi, Aaron is using his ears to potentially open up a new world of independence for other kids and adults with disabilities.

“Aaron is an amazing kid with a severe physical disability,” says Loren Davidson, one of Aaron’s physicians at Shriners Hospitals for Children Northern California and an associate professor of Pediatric Physical Medicine and Rehabilitation at UC Davis. “He’s so motivated to improve his quality of life; we really want to help him succeed. Dr. Joshi’s research is a great fit.”

This groundbreaking research is expanding Aaron’s ability to influence his surroundings by converting muscle signals into computer commands.

“We’re using the body’s natural electrical signals to help people control different tasks in their environment,” says Joshi, a professor in the Department of Mechanical and Aerospace Engineering in the College of Engineering. “They can control a cursor, a television – even a  robot.”

For Aaron and others born with-out limbs, people with neuromuscular diseases, quadriplegics and those with other severe disabilities, this technology could provide a huge opportunity in allowing them to perform tasks that are now virtually impossible.

Signal and noise

To help Aaron and others, Joshi and his team must capture electrical signals and translate them into action. It’s a difficult challenge.

“These signals are very small and can be easily corrupted,” says Joshi.

This is particularly true of brain signals, which must travel through the skull. To avoid placing sensors directly on the brain, Joshi chose another route, measuring muscle signals.

“The electrical signals from muscles are 10 to 100 times stronger than those from the brain,” says Joshi, “and that makes them much easier to measure.”

Because most people with severe physical disability can maintain control over their head and facial muscles, Joshi chose the ear.

Connecting a robot

To tap into Aaron’s muscles, researchers attach a sensor to his ear, which is then linked to a tablet computer. By using his ear muscles, Aaron moves a cursor to various targets on the screen. These signals are translated to a robot back at the UC Davis lab, which moves based on Aaron’s commands. Joshi notes that there’s a learning curve to work the system, and quite often test subjects don’t even know how they’re making the cursor move. The 10-year-old is unfazed.

“I just keep trying until I can make it work.”

Aaron plays a crucial role in Joshi’s research. While the lab has other volunteers, most of them are able-bodied college students. Because he is working to overcome his disability, Aaron already has insights into moving muscles in novel ways. To glean even more information, the team doesn’t bring Aaron to the lab; they bring the lab to Aaron.

“The family has been kind to have us over to the house to test these units,” says Joshi. “It’s a critical part of our research because ultimately we’d like people to use these devices in a real-world environment, where there’s interference from cell phones, televisions and computers.”

A more independent future

Aaron has impressed mother Juanita Garcia and the entire Joshi lab with his adaptability and eagerness to help. “He’s doing this on his own,” says Garcia. “I told him it would interfere with his free time, but he wanted to participate. He wants to help people.”

In years to come, this approach could allow people to control robots that perform specific tasks or even exoskeletons to help them move freely. While those uses are still in the realm of science fiction, Joshi envisions more immediate, and equally important, applications.

“It’s the little things,” says Joshi. “When a person requires 24-hour care and is capable of doing very little on their own, giving them a small measure of independence, like being able to change the channels on their television or turn a fan on or off, is really a big boost.”