A Prosthetic Arm That Gives Amputees the Sense of Touch
Innovator: Geoffrey Ling
Director of the biological technologies office at the Defense Advanced Research Projects Agency
Form and function
The modular prosthetic limb, an arm built at the Johns Hopkins Applied Physics Laboratory (APL) under a Darpa prosthetics program, has sensors and processing power to give amputees direct neural control and the feeling of touch.
Ling joined Darpa as a U.S. Army doctor in 2004. He started his prosthetics program there in 2006 after treating Afghan children who’d lost limbs to land mines.
A surgeon attaches electrodes to the patient’s motor cortex, the region of the brain that controls movement. After surgery, doctors connect wires from the electrodes to two leads on the top of the patient’s skull.
A computer wired to the electrodes can interpret signals from the patient’s brain and the arm’s sensors, so it moves properly and the patient can feel what’s grasped.
Without looking, test patients have been able to tell which of their prosthetic fingers a researcher is poking.
The limb works for about four hours on a full charge.
The prototype limb’s components cost about $400,000. The APL researchers have received $120 million from Darpa since 2006.
Following a successful test case, the research team has been in talks to begin commercializing the arm, says Michael McLoughlin, program manager at the Hopkins lab, who isn’t sure what the price for consumers might be. Cost will be a challenge, says Robert Froemke, an NYU neuroscience professor, and scientists don’t fully understand the brain’s motor signals. Says Froemke: “This is something that’s absolutely worth pursuing. This work’s amazing.”