A thermistor bolometer (an infrared radiation sensor) for a clinical tympanic thermometer has been newly developed and quantitatively evaluated. In order to mount the sensor on a tip of a flexible probe and to insert it into human's auricle, the sensor iscompleted in a very small size (2.2mm×2.3mm×0.8mm) using silicon micromachining technologies. Further the sensor can selectively detect the infrared radiation only from a tympanic membrane.
The sensor has been designed especially concerning the reduction of heat loss. To realize high sensitivity, a pair of infrared sensing regions of the sensor is made inthe shape of micro-air-bridge. It is encapsulated in a vacuum micro-chamber conformed between silicon substrates. The effectiveness of vacuum encapsulation is clearly proved by experiment.
The sensor shows the sufficient performance for the tympanic thermometer with the sensitivity of 5000V/W and the noise equivalent temperature difference (NETD) of 0.062°C at a D.C. bias voltage of 1.56V.
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