(Image via livescience.com) 

Staff Writer: Gwen Pichette 

Email: gpichette@umassd.edu

Prosthetic limbs have been around for thousands of years. Whether used for cosmetic reasons to mimic the appearance of a natural limb or for mechanical purposes to help with everyday tasks, it’s safe to say that they certainly have made life easier for amputees. 

A most trying hurdle for scientists has been finding the ability to emulate the physical sensations of a natural limb. This, which was never considered possible before, has just become a reality. 

A prosthetic arm that can feel temperature like a living limb has been produced in groundbreaking technological development. The new technology that has made this possible is MiniTouch, which was created with “affordable off-the-shelf electronics.”  

Scientists have known that amputees can feel sensations in their missing limbs for quite some time now. Though the sensations they could feel were often unpleasant, they could never distinguish temperature. 

These sensations amputees have felt are known as “phantom” sensations, a strange phenomenon that is all too familiar to amputees. “Phantom” sensations happen when amputees claim to experience physical sensations around the area of their missing limb as if it is still there. This includes “pressure, itching, or even burning” and “an actual feeling of pain, ranging from mild to severe.” 

These sensations happen mainly because of a mix-up in the nervous system signals between the spinal cord and the brain. A similar mix-up occurs with the nerves at the site of the amputee’s missing limb, which is partially what allows this new technology to work. 

The finger sensors attached to the prosthetic act as messengers. They send thermal information to nerve areas to the part of a limb that remains after an amputation, or what is known as the residual limb. Since the brain mistakenly believes that these are still connected to the limb, this allows for the nerves to receive the information — and the sensation is produced, just like magic.

MiniTouch has impressed scientists further with its convenience for prosthetic-wearers.

The unexpected loss of a limb is frightening enough. To further this discomfort, many amputees are forced to undergo additional surgeries after they have already lost a limb. For instance, amputees often undergo surgeries on their nerves in an attempt to reduce the dreaded phantom pains mentioned previously. To produce such a real sensation as temperature, it would be expected that a similar surgery would be required to stimulate the nerves. 

Yet, this is not the case with MiniTouch.

MiniTouch “requires no surgery” and, even better yet, “can be fitted to existing commercial prosthetic hands in a matter of hours.”

This means amputees would not have to worry about purchasing another prosthetic to use MiniTouch. This news is incredibly relieving for prosthetic wearers to hear, as the cost of your average commercial prosthetic remains exceedingly high. 

Prosthetics cost anywhere from $5,000 to a whopping $70,000, which doesn’t even include the cost of repairs. Mini-touch’s adaptability to pre-existing prosthetics provides one less anxiety to worry about. 

Additionally, MiniTouch is helping amputees feel more connected to the community around them with their new ability to perceive warmth. Scientists have said, “Touch without temperature is like vision without color.” The emergence of this new technology has bridged the sense of isolation that many amputees were experiencing. 

Roberto Rendo is one such prosthetic user who was lucky enough to participate in a 2023 trial run that stimulated the sensation of heat as MiniTouch does: 

“It was the first time in 20 years that I could actually feel the warmth of another person with my phantom limb. It’s like having a connection with someone. I would like to feel both of my kids’ hands when I walk down the street with them, holding their hands. That would be nice.”

In addition, the ability to feel temperature in prosthetics is a breakthrough because it works harmoniously with other sensations being developed. This includes feeling texture and proprioception, which improves the brain’s ability to know where a body part is. 

But scientists are not done yet and anticipate that the “next step would be to put them all together,” allowing amputees to experience “the full palate of sensations.” 

With temperature detection in prosthetic limbs now a reality, the prospect of even further prosthetic improvement looks incredibly promising.