The earliest prosthesis ever discovered is a big toe belonging to a noble woman in Egypt. Carved from a mixture of plaster, linen, and glue and attached to the foot using leather laces, the toe was a vital appendage to the Ancient Egyptians, who wore a style of sandal that depended on the largest digit of the foot.
Just a few thousand years later, the United States Defense Advanced Research Projects Agency (DARPA) has developed a prosthetic arm that communicates with its wearer’s motor and sensory cortexes. Using the power of thought alone, an amputee can grasp large and small objects, lift and lower them — and even feel them through the artificial hand.
The technology of prostheses has advanced much since Egypt’s toes, but only since robotics saw serious improvement in the middle of the 20th century have amputees had so much to look forward to. DARPA and other groups are rapidly developing prostheses that provide sensation almost identical to living human limbs, and it is all thanks to robotics.
How Robot Prostheses Work
Like Egypt’s toes and pop-culture pirates’ peg legs, mechanical prostheses are common throughout ancient history and the modern era. In fact, many amputees today continue to rely on simple prosthetic devices. Further, through the past, most amputees have benefitted from personal molding, meaning devices were and continue to be created for specific cases rather than mass-produced. The primary difference between the simplest artificial limbs of yesterday and today is the material composition: In areas equipped with Western medical practices, amputees typically sport prostheses of lightweight plastic, aluminum, and composites.
However, robotics has catapulted the field of prosthetics into the future. Whereas once it was nearly impossible to develop an articulated hand for someone missing an arm, now — thanks to research by DARPA and others — amputees can not only move fingers with precision, they can experience sensation through a replacement limb.
The primary method robot prostheses use to communicate with the body is electromyography sensors (EMG). Since scientists first discovered that electricity could stimulate muscles, engineers and others strove to apply this concept to prosthetics. In the 1980s, electrodes were sophisticated enough to detect contractions of the muscles and translate them into movement of a prosthesis. EMG is common and relatively inexpensive — but it requires amputees to learn to control their prostheses using unnatural movements that trigger the sensors. To resolve this issue, some amputees undergo targeted muscle reinnervation (TMR). In this therapy, doctors retrieve nerves once used to control missing limbs and replace them in areas that will connect to the prosthesis. The nerves amplify the brain’s messages, making the artificial limb’s movements more intuitive — but still amputees must relearn how to operate their limb.
To avoid this extensive training and physical therapy, medical researchers and engineers have delved even deeper into robotics. There already exist a few prostheses that use powerful microprocessors to evaluate the body’s systems without intervention from the amputee. Some artificial limbs are even equipped with artificial intelligence to give amputees the most comfortable and instinctual prosthetic experience. For example, Össur’s Rheo Knee is engineered to learn an amputee’s walking pattern to provide a natural and smooth gait for every individual. Similarly, Touch Bionics’ iLIMB is built with five electronic motors in its hand, one to control each finger. This design aims to provide amputees with a very high level of control. DARPA’s prosthesis uses nearly all of these technologies — including a form of TMR which places amputees’ nerves within the artificial limb — to provide a near-perfect simulacrum of the missing appendage.
How to Support Robotic Prosthetics
While robotic prostheses might exist, they are not exactly available to most amputees. More work is necessary to design and develop limbs that amputees can afford to purchase and use in the real world. Thus, the medical community urgently needs more experienced and enthusiastic biomedical engineers to contribute to prosthetics research. Acquiring a master’s degree in engineering online can be an excellent first step to improving robotics in prosthetics and helping those who need them acquire advanced artificial limbs.
Additionally, amputees can support prosthetics research of all kinds by participating in studies. Research programs tend to educate and elevate amputees with enhanced training and advanced technology, and researchers gain insights into the restrictions of current prostheses and the hardships of living with amputation. Prosthetics firms, medical universities, and even government agencies like DARPA are excellent places to begin searching for ways to help.
Cher Zevala is a content coordinator specializing in topics associated with the healthcare industry and innovations in the healthcare field. She is a contributing writer to Rehab Management. For more information, contact [email protected].