HIGH-RESOLUTION THIN-FILM TEMPERATURE SENSOR ARRAYS FOR MEDICAL APPLICATIONS

Highly sensitive and fast temperature sensors with sensitive areas of 0.14 × 0.1 mm2 have been arranged in arrays with interdistances of 0.4 mm consisting of thin films of amorphous germanium (a-Ge) to yield a high temperature coefficient of resistance of 2%/K at room temperature. The sensors are passivated by a 3-μm-thick silicon nitride layer and can be placed on glass, alumina and polymer substrates. The sensor noise limits the temperature resolution of 0.1 mK whereas the 90% response time is typically 3 ms. The electrical resistance of the sensor is in the range of 105 ohm. A measurement current of 1 μA causes selfheating of the sensor on glass substrates of less than 0.3 mK in water. This corresponds to a measured heat resistance of 3 × 103 K/W. Temperature distribution measurements in the cortex of rabbits and enzyme-calorimetric determinations have been accomplished with these devices. © 1990.