Adaptive thermal detectors using electrostatically controlled thermal conductance

When thermal infrared detectors are exposed to large signals, they are susceptible to a host of unwanted effects including intensity dependent noise and detectivity, nonlinearities in materials characteristics, and even temporary blindness or device damage. To combat these problems and to extend dynamic range, the responsivity and time constant of microbolometers have been controlled using electrostatic actuation. The responsivity has been demonstrated to switch over a factor of 60, with theoretical limits encompassing 4 to 5 orders of magnitude. High responsivity states correspond to free-standing bolometers, while discrete lower responsivity states are created by partially or completely actuating the device supports into contact with the substrate. Continuous tuning over a part of the range is demonstrated by utilizing electrostatic pressure to increase the thermal contact between discrete switching states.