Uncooled low-cost thermal imager based on micromachined CMOS integrated sensor array

Abstract

We present a micromachined 10/spl times/10 array of thermoelectric infrared sensors fabricated in a commercial complementary metal-oxide-semiconductor (CMOS) integrated circuit process with subsequent bulk-micromachining on wafer-scale. This array is used to demonstrate the feasibility of a low-cost thermal imager. The imager operates in ambient air, without thermal stabilization or cooling. The thermoelectric sensor principle allows one to measure dc radiation signals even without a radiation chopper. Each pixel contains an integrated heater, which allows calibration and self-testing of the imager. Addressing circuitry for the thermopiles and the heaters as well as a low-noise amplifier are integrated with the array on a single chip with a size of 5.5/spl times/6.2 mm. The imager achieves a temperature resolution of 530 mK with a low-cost polyethylene Fresnel lens. This performance allows application in presence detection, remote temperature measurement, and building control.