Micro-refrigerator, called as ultrafine cryoprobe, has been developed in order to realize the treatment of a small affected area, such as a pigment on skin or small early breast cancer. The size of the ultrafine cryoprobe is 0.55mm in diameter, which is same as the diameter of conventional injection needle. The ultrafine cryoprobe has double-tube structure and the surface temperature was reached at -50 °C. Additionally, through the freezing experiment using gelated water at 37°C, we confirmed the ultrafine cryoprobe has enough cooling power for cryosurgery for small lesion.
As a basic research of micro-refrigerator, thermal hydraulic characteristics of phase change flow in micro-double tube have been investigated. It was clarified that the variation of heat transfer characteristics by the bubble motion in the tube and the size of inner tube by the visualization experiment using low pressure water as a working fluid.
