Principle and in vivo Application of Measurement of Blood Flow by Heated Thermocouple with Feedback Controlled Heater

The heated thermocouple with constant heating current has been used by many authors for the measurement of the regional blood flow. A new method for the measurement of blood flow is proposed by employing the self-adjusting current heating with a feedback control system. In this method, the temperature difference between the hot and cold junctions is kept almost constant and quite small by setting properly the autornatically regulated heating current so that the effects of local heat accumulation by heating current on biological reaction in tissue may be avoided. Further this method is also superior in linearity, applicability to wider range of flow rate and prompt response than the method of constant current heating on both experimental and theoretical standpoints.