Whether it's a simple handshake or a full-body hug, the warmth of the other person adds a human touch to social interactions. Now, researchers have developed a device that allows amputees to experience this natural temperature sensation using a prosthetic leg.
The research team says this innovation is a first and paves the way for integrating many senses into prosthetic limbs.
Professor Solaiman Shokur, senior author of the study from the Swiss Federal Institute of Technology Lausanne, said that increasing the sensory feedback from a prosthetic limb is known to help people feel that the prosthesis is part of their body. Stated.
“To give a natural feeling, it's impossible without temperature,” he said.
Shokur added that this approach could help people with prosthetic limbs recognize whether an object is dangerously hot and distinguish between different materials.
“Beyond that, it opens a window into the more social aspects of touch,” he said.
Shokur et al., writing in the journal Med, have previously shown that it is possible to create the perception of warmth or coldness in an amputated hand by heating or cooling specific points on the remaining part of the arm. We report the method shown in .
Based on this phenomenon, the research team created MiniTouch, which places temperature sensors in the prosthetic hand where the phantom's thermal sensations are believed to be occurring.
When the sensor detects a temperature change away from the 32°C baseline, it sends a signal to the temperature controller. This relayed information to another component attached to the top of the prosthesis and in contact with the skin of the arm.
The temperature detected by the sensor was reproduced at the position of the arm that triggered the phantom sensation. In the current study, the device reproduced temperatures ranging from 20°C to 40°C.
As a result, the person felt a thermal sensation at the location of the missing hand's temperature sensor.
To test MiniTouch, researchers attached it to the prosthetic leg of Fabrizio, a 57-year-old man whose right arm had been amputated below the elbow.
The researchers found that Fabrizio was able to use the device to distinguish between identical-looking bottles containing cold, hot, or room-temperature water with 100% accuracy. His accuracy when the device was switched off was 33%.
Using MiniTouch while blindfolded, Fabrizio was also able to distinguish between copper, glass, and plastic plates with the same accuracy as using his other intact hand. But once the device was switched off, his choices were dictated by chance.
Additionally, MiniTouch improved Fabrizio's ability to distinguish between his real arm and his prosthetic arm when he was blindfolded. However, the uninjured hand was more accurate, perhaps because it also sensed information such as texture, Shokul said.
The device also improved Fabrizio's accuracy in sorting boxes of hot and cold steel cubes in one minute, but not the speed.
Fabrizio said the hallucinatory sensations in his missing hand were more intense than in his healthy hand when he perceived hot or cold cubes.
“When I had an accident when I was 20 years old, I tried a prosthetic arm that allowed me to move easily. Instead, by using these new technologies, I can better understand what I'm touching. ” he said.
The authors say the device should be tested on a larger group of patients, but because MiniTouch does not require surgery and is based on off-the-shelf electronics, it is compatible with existing prostheses. They say it bolts on, is easily customizable, and is relatively simple to use. cheap.
The paper's other senior author, Professor Silvestro Micela of the Swiss Federal Institute of Technology Lausanne and the Sant'Anna School of Advanced Studies in Italy, said the team has now developed a single wearable device that provides amputees with the following capabilities: He said he plans to create a system. With the prosthesis, you experience a variety of sensations, including pressure, texture, position, temperature, and moisture.
“For us, this is [really] It’s a big next step,” Misera said.
Dr. Sigrid Dupin, an expert on sensory feedback in prosthetic limbs at University College Dublin who was not involved in the study, said a fully integrated system is a huge step forward in research into thermal feedback in prosthetic limbs, and will help people understand how they feel in their prosthetic limbs. He said it could help people feel better. Prosthetics were part of their bodies.
But she cautioned that the research team had previously shown that it was impossible to induce phantom heat sensations in all amputee patients and that it was inconsistent in some people.
“While I'm excited about this research and it shows promising developments, … people can't expect these new devices to be introduced into our health care system in the short term.” she said.
