Whether it is a simple handshake or a full-body hug, the warmth of another person adds a human touch to social interactions. Now researchers have created a device that allows people with amputations to experience such natural temperature sensations using their prostheses.
The team claims that their innovation is groundbreaking and will allow for the incorporation of various sensations into prosthetic limbs.
According to Prof Solaiman Shokur, one of the main authors of the study conducted at the Swiss Federal Institute of Technology Lausanne, it has been established that enhancing sensory feedback through a prosthesis can aid individuals in perceiving it as a natural extension of their own body.
He stated that in order to create a natural feeling, temperature is necessary.
Shokur mentioned that this method could potentially allow individuals with prosthetic limbs to sense if an object is dangerously hot and differentiate between various materials.
“He mentioned that it not only provides access, but also introduces a more communal aspect to the concept of touch.”
In a publication in the journal Med, Shokur and fellow researchers discuss their previous findings on the ability to induce feelings of warmth or coolness in an amputated hand by manipulating temperature at specific points on the remaining section of the arm.
Expanding on this occurrence, the group developed the MiniTouch, incorporating a temperature sensor on a prosthetic hand to detect the source of the phantom thermal sensations experienced by an individual.
If the sensor detected a deviation in temperature from the standard of 32C, it transmitted a message to a temperature regulator. This communicated the data to a separate part attached to the top of the prosthetic and in contact with the arm’s skin.
The sensor detected a temperature, which was then replicated on the arm at the designated trigger spot to create phantom sensations. In this study, the device reproduced temperatures ranging from 20C to 40C.
In summary, the individual felt a sensation of heat in their absent hand, at the spot where the temperature sensor was placed.
The MiniTouch was tested on Fabrizio, a 57-year-old man who had his right arm amputated below the elbow. The researchers attached it to his prosthetic limb.
The team discovered that with the device, Fabrizio was able to accurately differentiate between bottles that appeared identical but contained cold, hot, or room-temperature water, with a 100% success rate. However, without the device, his success rate dropped to 33%.
Even while blindfolded, Fabrizio was able to accurately differentiate between pieces of copper, glass, and plastic with the MiniTouch. However, without the device, his guesses were random.
Moreover, the MiniTouch enhanced Fabrizio’s capacity to differentiate between genuine and artificial arms while blindfolded. Shokur noted that his accuracy was slightly better with his uninjured hand, potentially due to its ability to perceive tactile information like texture.
The device enhanced Fabrizio’s precision, but did not increase his speed, while organizing a box of hot and cold steel cubes within one minute.
Fabrizio reported that the feeling of his phantom limb was stronger in his missing hand compared to his intact hand when sensing hot or cold cubes.
He explained, “When I was 20 years old and had my accident, I tested a prosthetic hand that only allowed for basic movement. However, with the advancements in technology, I am now able to have a better understanding of what I am touching.”
The creators suggest that the device should be evaluated in a bigger sample of individuals. They also mention that the MiniTouch does not involve invasive procedures and utilizes easily accessible technology. This allows it to be attached to current prosthetics, personalized easily, and is reasonably priced.
Silvestro Micera, a professor and senior author of the paper, is from the Swiss Federal Institute of Technology Lausanne and the Sant’Anna School of Advanced Studies in Italy. He stated that the team’s next goal is to develop a single wearable system that can provide individuals with amputations the opportunity to feel various sensations through their prostheses, such as pressure, texture, position, temperature, and wetness.
Micera stated that this would be a significant advancement for us.
According to Dr. Sigrid Dupan, a specialist in sensory feedback for prosthetics at University College Dublin, the complete integration of the system represents significant progress in studying thermal feedback for artificial limbs. This advancement has the potential to make individuals feel more connected to their prosthetics as if they were a natural part of their bodies.
However, she advised that the team has previously demonstrated that it is not feasible to induce phantom thermal sensations in all individuals with amputations, as they were not consistently present in some cases.
She expressed enthusiasm for the research and its promising advancements, but cautioned that people should not anticipate quick integration of these new devices into our healthcare system.