DEVELOPMENT OF A MICRO COOLING PROBE FOR BRAIN MAPPING

摘要

Experimental data from the. use of local cooling methods in animals and human cortex indicate that when brain tissue is cooled down io temperatures between 0 and 20°C, local synaptic activity are disrupted without causing permanent injury to the tissue. This paper outlines the major techniques used in brain mapping procedures and describes the design, construction and theoretical analysis for a micro cooling probe that can be used to apply selective and localised cooling in a brain mapping procedure. A two dimensional steady state numerical solution for the bio heat equation was carried out, indicating that when local cooling of 4°C is applied to the surface of a brain tissue, temperatures between 4 and 20°C at depths close to 4mm can be achieved. The proposed probe cooling system comprised of a thermo electric cooler, appropriate heat exchangers, a coolant circulating pump,, cooling head (probe tip), and connecting micro tubing with an internal diameter of 0.258mm. Computational fluid dynamics (CFD) was used to assess, various probe designs in terms of pressure losses through the micro tubing network and probe tip. Experimental tests were carried out to determine cooling probe performance with results showing that tip temperatures close to 0°C were achieved, which satisfies the cooling requirements for brain mapping procedure.