Potential NASA Commercial Applications: Thermopile detectors have some desirable characteristics that make them better suited for certain applications than bolometers and pyroelectric/ferroelectric detectors. They are passive devices, require no electrical bias, and generate a voltage output that is proportional to the input radiation signal. They are also typically uncooled and are insensitive to substrate temperature variations, making temperature stabilization unnecessary. They are highly linear, which combined with their insensitivity to substrate temperature, make them ideal for accurate radiometry. Finally, they require no optical chopper and they have negligible 1/f noise, provided the readout amplifier has high input impedance. These properties make them well suited for broadband spectral detection applications. A two-dimensional thermopile array built over CMOS readout circuitry in the substrate will allow large format staring imaging arrays with low 1/f noise for radiometric applications.