Rensselaer Polytechnic Institute researchers are developing a tiny implantable “refrigerator” that is designed to detect and then interrupt the epileptic activity in the brain through cooling:
The heat spreader being developed at Rensselaer utilizes a phase-change heat process, the same mechanism that the human body uses to cool itself, to transfer and distribute heat in the brain. The fundamental principal behind the operation of the heat spreader is evaporation and condensation, similar to perspiration. Using a pure substance, saturated conditions are created inside the heat pipe, resulting in evaporation in the heated regions. Heat entering the pipe turns the liquid water to vapor, which is forced along the pipe by high pressure where it is condensed in the cooler regions. The dissipated heat is then pushed out of the heat pipe, and the wicking structure pumps the liquid back to the evaporator.
“The heat spreader we created for this implant device acts as a very efficient thermal conductor, spreading and releasing the heat without minimal temperature increase, thereby preventing any potential tissue damage to the brain,” said Peterson. “The brain can tolerate temperature reductions on the order of 18 to 20°C without sustaining permanent damage. However, the brain cannot tolerate temperature increases over 0.5°C. This requires that the heat both absorbed and generated by the device be spread across a much larger surface area.”
Implanted on the neocortex of the brain, close to where erratic electrical activity is causing the epileptic seizure, the implant device is designed to detect the unusual level of electrical activity that accompanies these types of seizures. The implant device then is activated to cool a small area of the brain from approximately 38°C (100°F) to 20°C (68°F) to render that part of the brain temporarily non-functional and seizure-free, according to researchers.
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