Rensselaer researchers are developing a tiny, highly efficient heat spreader to be used in a new device to be implanted in the brains of patients who suffer from severe epileptic seizures. The implant device is designed to detect and arrest epileptic seizures as they begin by cooling a small region of the brain, thereby effectively blocking the erratic electrical activity.

G. P. “Bud” Peterson, provost and professor of mechanical, aerospace, and nuclear engineering at Rensselaer, and his team are collaborating with researchers at Washington University School of Medicine in St. Louis to design, model, test, and develop the implant device. The research and the potential of the device were featured in the July 16 issue of New Scientist.

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 principle 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 spreader, 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 spreader, 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,” says Peterson.

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.

The heat spreader being developed allows the heat generated and absorbed by the implant device to be effectively released without a significant increase in temperature.

Originally published in Rensselaer Magazine, Fall 2005

Published November 1, 2005