| Medical

Smart Artificial Limbs

Traditional leg prosthetics enable amputees to maintain mobility and lead more active lives. Leg prosthetics most commonly fit amputees’ residual limbs via a socket that encloses the limb like a wooden clog. Because the socket exerts pressure on the limb’s soft tissue, pain and chafing, sores and blisters, and infection can occur. Amputees often must have their socket prosthetics adjusted regularly, which is inconvenient and costly. Consequently, many amputees give up prosthetics for wheelchairs.

Researchers have developed a “smart” artificial leg equipped with specially designed sensors to monitor walking gait, alert users to prosthetic wear and tear, and warn of potential infection risk. The Monitoring OsseoIntegrated Prostheses (MOIP) use an alternative limb type called an osseointegrated prosthetic that includes a titanium fixture surgically implanted into the thigh bone, or femur. Bone grows, or “osseointegrates,” at the connection point with the implant, leaving only a small metallic connector protruding from the remaining leg. An accompanying artificial limb then can be attached or detached at will. The same procedure can be performed for upper limbs.

The advantages of osseointegrated prosthetics include less pain, a fluid walking motion, and a more stable, better-fitting limb. But because metal sticks out of the residual limb, infection is a constant risk. To address this issue, MOIP will focus on infection detection, eradication, and prevention by developing both electrochemical sense-and-respond approaches and “smart” skin technologies. This includes a critical bio-compatible sensor array embedded within an amputee’s residual limb, coupled with additional sensors on the osseointegrated prosthetic itself. The first technology of its kind, the array tracks changes in body temperature and pH balance — indicators of possible infection. It also monitors how well the bone and prosthetic limb fuse together and heal, allowing doctors to dramatically speed the recuperation process of warfighters.

Over time, the sensors evaluate the prosthetic’s strength, how much stress a user’s body places on it, and any changes to movement and walking gait. Because the sensors transmit information wirelessly, doctors also could potentially study patient data via a handheld reader.

For more information, contact the Office of Naval Research at This email address is being protected from spambots. You need JavaScript enabled to view it.; 703-696-5031.