2024-02-10 02:44:28
Sensory feedback is important for amputees to be able to explore and interact with their environment. Now, researchers have developed a device that allows amputees to sense and respond to temperature by delivering thermal information from the prosthetic fingertip to the amputee’s residual limb. The “MiniTouch” device was presented on February 9 in the magazine With, uses off-the-shelf electronics, can be integrated into commercially available prosthetic limbs, and does not require surgery. Using the thermally sensitive prosthetic hand, a 57-year-old amputee was able to distinguish between objects at different temperatures and manually sort physical contact with other humans.
This is a very simple idea that can be easily incorporated into commercial prostheses. Temperature is one of the last frontiers for restoring sensation to robotic hands. For the first time, we are really close to restoring the entire palette of sensations to amputees.”
Silvestro Mitzera, Senior Writer of École Polytechnique Fédérale de Lausanne and Scuola Superiore Sant’Anna
The team previously showed that their thermoaccessible technology can restore passive thermosensation in 17/27 amputees. In the new study, they show that the MiniTouch can be easily integrated into commercial prosthetic limbs and that it enables active thermosensation during tasks that require feedback between sensory and motor neurons.
Beyond the functional importance of the ability to feel heat and cold, thermal information can also improve amputees’ sense of embodiment and their ability to experience emotional contact. “Adding temperature information makes the touch more human-like,” says senior author Solaiman Shokur (@SolaimanShokur) of École Polytechnique Fédérale de Lausanne. “We think that the ability to sense temperature will improve the embodiment of amputees – the feeling that ‘this hand is mine’.”
To do this, they integrated the MiniTouch into the personal prosthesis of a 57-year-old male who had undergone a tradial amputation 37 years earlier by linking the device to a point on the participant’s residual limb that evoked thermal sensations in his phantom finger. . Next, they tested his ability to distinguish between objects at different temperatures and objects made of different materials.
Using the MiniTouch, the participant was able to distinguish between three visually indistinguishable bottles containing cold (12°C), cool (24°C), or warm (40°C) water with 100% accuracy, while without the device, his accuracy was Only 33%. The MiniTouch device also improved its ability to quickly and accurately sort metal cubes at different temperatures.
“When you get to a certain level of dexterity with robotic hands, you really need to have sensory feedback to be able to use the robotic hand to its full potential,” Shukor says.
Finally, the MiniTouch device improved the participant’s ability to distinguish between human and prosthetic arms while blindfolded – from 60% accuracy without the device to 80% with the device. However, his ability to sense human touch through his prosthesis was still limited compared to his uninjured arm, and the researchers hypothesize that this is due to limitations in other non-thermal sensory inputs such as skin softness and texture. Other technologies are available to enable these other sensory inputs, and the next step is to begin integrating these technologies into a single prosthetic limb.
“Our goal now is to develop a multimodal system that combines touch, proprioception and temperature sensations,” says Shukor. “With that kind of system, people will be able to tell you, ‘It’s soft and warm,’ or ‘It’s hard and cold.'”
The researchers say their technology is ready to use from a technical standpoint, but more safety testing is needed before it reaches the clinic, and they have plans to further improve the device so it can be more easily adjusted. Future models could also build on the Minitouch to integrate thermal information from multiple points on an amputee’s phantom limb; For example, allowing people to differentiate between thermal and tactile sensations on their finger and thumb may help them grasp a hot drink, while allowing sensation on the back of the hand may improve the sense of human connection by allowing amputees to sense when another person is touching their hand.
This research was supported by the Bertarelli Foundation, the Swiss National Science Foundation, the European Union’s Horizon 2020 Research and Innovation Program, the Horizon Europe Research & Innovation Program and the Ministry of University and Research.
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