New Wearable, Thin-film Device Helps Patients Feel Temperature in Their Amputated Limbs
Researchers from the Uniformed Services University and the Johns Hopkins Applied Physics Lab have developed a wearable, thin-film device to help individuals with amputation feel temperature in their phantom limbs
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Researchers from USU helped develop a device, known as the wearable thin-film thermoelectric cooler (TFTEC), that will help individuals with amputations feel temperature in their phantom limb. The device is one of the world's smallest, most intense, and fastest refrigeration devices. (Photo courtesy of Johns Hopkins APL) |
August 3, 2023 by Sarah Marshall
Individuals with amputation often experience phantom limb pain, a painful sensation that they perceive in their missing limb. While this pain has been described for centuries, researchers from the Uniformed Services University (USU) and the Johns Hopkins Applied Physics Lab (APL) may now have a new tool to help treat this phenomenon.
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The device, similar to a small bandage, provides intense cooling in less than a second. (Photo courtesy of Johns Hopkins APL) |
Researchers from the APL began developing these advanced thin-film thermoelectric materials in 2016 for another project called Controlled Hierarchically Engineered Superlattice Structures (CHESS). Since these materials were proving to be successful, by 2019 they were applying them to other capabilities to support the Department of Defense, like cooling computer chips and engine components. They then decided to test this technology to see if it could help individuals with amputations to feel temperature in their phantom or residual limbs, with the ultimate goal of mitigating pain or improving sensory feedback from artificial limbs. They brought in researchers from USU’s Center for Rehabilitation Sciences Research (CRSR) in the Department of Physical Medicine & Rehabilitation (PM&R) to help create the TFTEC.
The device, a little more than one millimeter thick, weighs only 0.05 grams. Similar to a small bandage, it provides intense cooling in less than a second. After extensively testing the device for such sensory applications, including injured service members with amputation, they recently published their results in Nature Biomedical Engineering on July 27. The study indicates that the device elicited cooling sensations in phantom limbs in all of its participants during a “cold detection task,” whereas other technologies were only able to help detect temperature in half of the participants – and the TFTEC did so eight times faster and with three times the intensity. The TFTEC also used only half the amount of energy, compared to other thermoelectric devices that are currently being used.
“This groundbreaking development opens the door to a wide array of new capabilities, especially for individuals with amputation, including our wounded warriors,” said Dr. Paul Pasquina, chair of PM&R at USU.
He explained that individuals with limb loss often retain the sensory nerves that went with their missing limb, which offers the opportunity to restore sensation. While experiments to date have looked at restoring sensory modalities, such as vibration and or electrical stimulation, this is the first to transmit the sensation of cold.
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Dr. Paul Pasquina, chair of PM&R, supported the development of a new device that will help amputees be able to feel temperature in their phantom limb. (USU photo) |
“We still don’t know its therapeutic benefits, but we do know that ice/cold therapy is frequently used in other settings such as for sports injury, muscle spasm, and pain,” Pasquina said. “Therefore, it is exciting technology that we look forward to better understanding its therapeutic value.”
Pasquina praised the collaboration between the CRSR and APL scientists. “It has been a privilege to work with such a talented group of engineers, scientists and clinicians to help solve some real-world and challenging problems that patients, particularly our wounded warriors with limb loss, face every day.”
