  Nanoelectromechanical (NEMS) resonators are promising uncooled thermal
infrared (IR) detectors to overcome existing sensitivity limits. Here, we
investigated nanoelectromechanical trampoline resonators made of silicon
nitride (SiN) as thermal IR detectors. Trampolines have an enhanced
responsivity of more than two orders of magnitude compared to state-of-the-art
SiN drums. The characterized NEMS trampoline IR detectors yield a sensitivity
in terms of noise equivalent power (NEP) of 7pW/$\sqrt{Hz}$ and a thermal
response time as low as 4 ms. The detector area features an impedance-matched
metal thin-film absorber with a spectrally flat absorption of 50% over the
entire mid-IR spectral range from 1$\mu m$ to 25$\mu m$.
