Noncontact transducer for monitoring blood temperature during extracorporeal circulation

A zero-heat-flow transducer was designed to monitor blood temperature during extracorporeal circulation. The probe was covered with a thick metal shell that was heated or cooled to match the surface temperature of the circulation tube, causing the net heat flow across theprobe to be reduced to zero. Experiments showed that fluid temperatures between 20 degrees C and 40 degrees C measured from the surface of a Tygon tube would be accurate within +/- 0.2 degrees C. Response time of ramp-like change in the fluid temperature from 20 degrees C to 30 degrees C was about 3 min. Animal and clinical tests showed this device to be highly accurate.