Whether it’s a simple handshake or a full-body hug, the warmth of another person adds a human touch to social interactions. Now researchers have developed a device that allows people with amputations to experience this type of natural feeling of warmth using their prosthetics.
The team says that this innovation is a first and paves the way for integrating many senses into artificial limbs.
Prof Solaiman Şokur, a senior author of the study at the Swiss Federal Institute of Technology Lausanne, said it was known that increasing the sensory feedback of a prosthesis could help people feel that an artificial limb was part of their body.
“You can’t do this without warmth to give it a natural feel,” he said.
Shokur added that the approach could also help people with artificial limbs detect whether an object is dangerously hot and distinguish between different materials.
“Beyond that, it opens a window into the more social side of touch,” he said.
Writing in the journal Med, Shokur and colleagues reported how they had previously shown that it was possible to create the perception of warmth or coolness in an amputated hand by heating or cooling specific points on the rest of a person’s arm.
Drawing on this phenomenon, the team created the MiniTouch, in which a temperature sensor is placed on someone’s prosthetic hand where phantom thermal sensations occur.
When the sensor detected a change in temperature away from the 32°C baseline, it sent a signal to the temperature controller. This relayed the information to another component that was mounted on the top of the prosthesis and contacted the skin of the arm.
The temperature detected by the sensor was then reproduced in the arm at the trigger point for phantom sensations. In the current study, the device reproduced temperatures between 20C and 40C.
As a result, the person detected a thermal sensation in the lost hand, where the temperature sensor was located.
To test the MiniTouch, researchers implanted it into the prosthesis of 57-year-old Fabrizio, whose right arm was amputated below the elbow.
The team found that when using the device, Fabrizio could distinguish between identical-looking bottles containing cold, hot or room temperature water with 100% accuracy. When the device was turned off, its accuracy was 33%.
Using the MiniTouch while blindfolded, Fabrizio was also able to distinguish copper, glass, and plastic sheets with an accuracy equal to that when using his good other hand. However, when the device was turned off, their choice was left to chance.
In addition, MiniTouch increased Fabrizio’s ability to distinguish between real and prosthetic arms while blindfolded; However, Shokur said his accuracy was higher with his good hand, possibly because it also detects information such as texture.
The device also improved Fabrizio’s accuracy, though not his speed, in sorting a box of hot and cold steel cubes in a minute.
Fabrizio said that the phantom sensation in his missing hand was more intense than in his good hand when detecting hot or cold cubes.
“When I had an accident when I was 20, I tried a prosthetic hand that gave me simple movement; “Instead, I can better understand what I am touching with these new technologies,” he said.
Although the authors say that the device should be tested in a larger group of patients, they note that MiniTouch does not require surgery and is based on off-the-shelf electronic devices; This means that it can be screwed onto existing dentures, is easily customized, and is relatively inexpensive.
Another senior author of the paper, Professor Silvestro Micera from the Swiss Federal Institute of Technology Lausanne and the Sant’Anna School of Advanced Studies in Italy, said the team now plans to create a single wearable system that will give people with amputations this ability. Experiencing many different sensations such as pressure, texture, position, temperature and wetness while using their prosthetics.
“This is for us [really] The next big step,” Micera said.
Sensory feedback expert for prosthetics Dr. from University College Dublin, who was not involved in the research. Sigrid Dupan said the fully integrated system was a major step forward in thermal feedback research for artificial limbs and could help people feel their bodies. prosthetics were part of their bodies.
But he cautioned that the team had previously shown that it was not possible to induce phantom thermal sensations in all people with amputations, and not consistently in some.
“I’m excited about the research and it shows promising advances, but… people can’t expect these new devices to be implemented into our healthcare system any time soon,” he said.