Cryosurgery is a surgical method using freezing in a biological tissue by local cooling. In order to generate frozen region in biological tissue, a local cooling device, which is called as cryoprobe, has been used. Low temperature and high cooling performance are required to cryoprobe. Cryosurgery already has been applied to the treatment of a liver cancer or prostate cancer. However, it is difficult to apply the conventional cryosurgery to smaller treatment area.
To overcome these problems, our group has developed the cryoprobe with precise heat transfer control in order to treat the thin affected area in the skin or small early stomach cancer. The performance of the cryoprobe we developed has been evaluated by numerical simulations and animal experiments. Furthermore, we aim to achieve frozen region control by temperature control. This project has been conducted by the collaboration with the Division of Dermatology, Medical Department in Tohoku University
Thermal therapy, such as moxibustion in oriental medicine, has been developed in Asian countries, mainly China. On the other hand, the condition of treatment has depended on the experiences of medical doctors and the treatment effects and heat transfer process inside human body has not been evaluated quantitatively. In order to understand the thermal therapy quantitatively, our group developed the abdominal heating device and radiation heater. We evaluated the heat transfer characteristics of these devices experimentaly and the treatment effect by these devices has been also evaluated by the numerical simulation and clinical experiments. This project has been conducted by the collaboration with Advanced research center of Asian Traditional medicine, Medical Department in Tohoku University.
In order to realize quantitative and safe thermal therapy, it is important to estimate the heat transfer phenomena when biological tissue is heated or cooled. Such heat transfer phenomena have been described by Pennes’ bioheat transfer equation. The characteristics predicted by bioheat transfer equation have been analyzed by using analytical solutions. Additionally, accurate thermophysical properties are required to simulate treatments numerically. However, biological tissue has variable thermophysical properties depending on individuals or variation of blood flow and metabolism. Our group has developed the noninvasive and in-situ method to determine thermophysical properties of biological tissue. This project has been conducted by the collaboration with Advanced research center of Asian Traditional medicine, Medical Department in Tohoku University.
"Thermoelectric Actuator" is the actuator made by combination of shape memory alloy (SMA) and Peltier elements. The direction of heat flux can be changed by switching the direction of electric current applied on Peltier elements. So, the shape of SMA can be controlled by cooling or heating continuously. The actively actuating catheter is developing by utilizing the system of thermoelectric actuator If the technology is applied in the real operation, patients' pain will be drastically alleviated by controlling the shape of the catheter with high amount of freedom. The artificial heart was developed with thermoelectric actuator. The same action with heartbeat can be duplicated by repeating cooling and heating of SMA continuously. Electric saving, compact and lightweight artificial heart may be realized.
