Rehabilitation experts at the University of Pittsburgh School of Medicine hope to one day give people with an arm amputation a prosthetic limb that not only moves like a natural one, but “feels” like it, too. They expect such sensation will improve dexterous control of the device and give users greater intuition about what they are doing with their prosthetic.
With funding from the Defense Advanced Research Projects Agency (DARPA)’s Hand Proprioception and Touch Interfaces (HAPTIX) program, Robert Gaunt, Ph.D., assistant professor, Department of Physical Medicine and Rehabilitation (PM&R), Pitt School of Medicine and a multidisciplinary research team from Pitt, West Virginia University and Ripple LLC will begin developing the technology with the aim of being able to test it in patients’ homes within four years.
“Advanced prosthetic limbs that behave like the hand and arm they are replacing have been an unrealized promise for many years largely because until recently, the technologies to really accomplish this goal simply haven’t been available,” Dr. Gaunt said. “To make the most of these new capabilities, we have to integrate the prosthetic into the remaining neural circuitry so the patient can use it like a regular hand that, for example, can pick up a pen, gently hold an egg or turn a stuck doorknob.”
In the 18-month, first phase of the project, the team will recruit five volunteers to try to demonstrate that stimulation of the sensory portion of the spinal cord nerves, which would normally innervate the hand and forearm, can cause the amputee to feel distinct sensations of touch and joint movement in the “phantom” hand and wrist.
They also plan to insert fine-wire electrodes into the forearm muscles of able-bodied volunteers to collect and interpret muscle signals to guide movement of a virtual prosthetic hand to control hand opening and closing, as well as thumb movement. Eventually, the team aims to devise a fully implantable system for home use.
DARPA’s Hand Proprioception and Touch Interfaces (HAPTIX) program aims to develop fully implantable, modular and reconfigurable neural-interface systems that would enable intuitive, dexterous control of advanced upper-limb prosthetic devices. In a major step toward achieving these goals, DARPA has awarded prime contracts for Phase 1 of HAPTIX
DARPA’s Hand Proprioception and Touch Interfaces (HAPTIX) program seeks to develop advanced neural interfaces that would enable prosthetic hand systems to move and provide sensation like natural hands. To help the performers more quickly and cost-effectively conduct their research, DARPA is providing prosthetics simulation software for testing designs
To help HAPTIX performers more quickly and effectively conduct their research, DARPA is providing each team with open source simulation software in which to test their designs. The software includes a variant of the DARPA Robotics Challenge Simulator from the June 2013 Virtual Robotics Challenge, the first stage of the DARPA Robotics Challenge.
“The ultimate goal for HAPTIX is to create a device that is safe, effective and reliable enough for use in everyday activities,” said Doug Weber, DARPA program manager. “DARPA is partnering with scientists at the Food and Drug Administration to help develop standards for verifying safety and quantifying benefits of this new class of advanced technologies. We hope to streamline the process of validating technologies that can help our military Service members and veterans who have been injured while serving our country.”
DARPA is evaluating several distinct technical approaches in Phase 1. Those that prove successful would continue into Phase 2, which would integrate selected technology components into a complete HAPTIX test system. The agency plans to initiate take-home trials of a complete, FDA-approved HAPTIX prosthesis system within four years.
The name HAPTIX is a play on the word haptics, referring to the sense of touch. The program plans to adapt one of the prosthetic limb systems developed recently under DARPA’s Revolutionizing Prosthetics program to incorporate interfaces that provide intuitive control and sensory feedback to users. These interfaces would build on advanced neural-interface technologies being developed through DARPA’s Reliable Neural-Interface Technology (RE-NET) program.
Where appropriate, HAPTIX teams intend to leverage commercially available technologies such as intramuscular electrodes and lead technologies developed initially for cardiac pacemakers and now used in several modern implantable medical devices. The program also plans to test advanced microelectrode array and nerve cuff electrode technologies that have been developed over the past two decades with support from the National Institutes of Health, the Department of Veterans Affairs and DARPA.
DARPA is working with teams led by the following institutions:
Case Western Reserve University
University of Pittsburgh
University of Utah
University of Florida
SOURCES – DARPA, University of Pittsburgh School of Medicine