Innovative Prosthetic Hand Technology lets a Human Detect Temperature Changes

Feeling someone’s warmth during a handshake or hug gives social interactions a unique flavor. Researchers have created a device to enable prosthetic users to experience these natural temperature sensations.

A senior researcher at the Swiss Federal Institute of Technology Lausanne, Prof. Solaiman Shokur, clarified that improving sensory feedback from a prosthesis can help people feel as though their artificial limb is an organic part of their body. He underlined the importance of adding a feeling of temperature to prosthetics to provide a more realistic experience. Shokur also emphasized how this technology could improve functionality and safety by helping users distinguish between various materials and detect hot objects.

Previous studies by the team showed that by adjusting the temperature of the remaining portion of the arm, it was possible to replicate the sensations of warmth or coolness in an amputated hand. They expanded this idea to create the MiniTouch gadget, which has a temperature sensor attached to the prosthetic hand. A controller receives information from the sensor when it notices a change in temperature and uses it to replicate the feeling on the user’s arm.

The gadget effectively imitated temperatures between 20°C and 40°C in the current study, enabling users to feel missing heat in the hand. This novel method not only improves the use of prosthetic limbs, but also creates opportunities for more socially engaging and natural interactions for people who have lost limbs.

Fabrizio got a new prosthetic hand and wasn’t sure how it would feel. But when he touched one of the researchers who gave it to him, he felt something unexpected. Fabrizio, a 57-year-old man from Pistoia, Italy, said, “When one of the researchers put the sensor on his own body, I could feel the warmth of another person with my phantom hand. It made me feel very emotional, like I was reconnecting with someone.

Using the MiniTouch device, Fabrizio demonstrated remarkable accuracy in discriminating between bottles containing water at different temperatures. Results showed that he could accurately distinguish between water temperatures of 53°F (cold), 75°F (cool), and 104°F (hot), achieving perfect accuracy. In contrast, without the device, Fabrizio’s accuracy dropped significantly to just 33%.

Furthermore, Fabrizio was able to differentiate between human and prosthetic arms while blindfolded with an impressive accuracy of 80%, thanks to the warmth sensation provided by the MiniTouch. Without the device, his accuracy decreased to 60%.

Co-senior researcher Solaiman Shokur, who chairs translational neuro-engineering at École Polytechnique Fédérale de Lausanne in Switzerland, emphasized the significance of adding temperature information to enhance the sense of touch. He noted that this addition could improve amputees’ embodiment, enhancing their feeling of ownership over their prosthetic limb.

Keywords; Prosthetic hand, sensory feedback, Phantom limb

More information:

F. Iberite et al. Restoration of natural thermal sensation in upper-limb amputees. Science. Vol. 380, May 18, 2023, p. 731. doi: 10.1126/science.adf6121.  

Hao M, Chou C.H. et al. Restoring finger-specific sensory feedback for trans-radial amputees via non-invasive evoked tactile sensation. IEEE Open J. Eng. Med. Biol. 2020; 1: 98-107.

R. S. Johansson, J. R. Flanagan, Coding and use of tactile signals from the fingertips in object manipulation tasks. Nat. Rev. Neurosci.10, 345–359 (2009).

Chou C.H., Zhang J., et al., Restoring finger-specific sensory feedback for trans-radial amputees via non-invasive evoked tactile sensation. IEEE Open J. Eng. Med. Biol. 2020; 1: 98-107.

Raspopovic S. Advanced limb neural prostheses. Science. 2020; 370: 290-291.