Fast and high resolution thermal detector based on an aluminum nitride piezoelectric microelectromechanical resonator with an integrated suspended heat absorbing element

This letter presents a miniaturized, fast, and high resolution thermal detector, in which a heat absorbing element and a temperature sensitive microelectromechanical system (MEMS) resonator are perfectly overlapped but separated by a microscale air gap. This unique design guarantees efficient and fast (similar to 10s mu s) heat transfer from the absorbing element to the temperature sensitive device and enables high resolution thermal power detection (similar to nW), thanks to the low noise performance of the high quality factor (Q = 2305) MEMS resonant thermal detector. A device prototype was fabricated, and its detection capabilities were experimentally characterized. A thermal power as low as 150nW was experimentally measured, and a noise equivalent power of 6.5 nW/Hz(1/2) was extracted. A device thermal time constant of only 350 mu s was measured (smallest ever reported for MEMS resonant thermal detectors), indicating the great potential of the proposed technology for the implementation of ultra-fast and high resolution un-cooled resonant thermal detectors. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794074]