Nanoresonators are used in research and industry to detect minute-sub-micrometric-masses and forces. These tiny sensors, which work by measuring variations in resonance frequency when in the presence of the unidentified molecule, do have a major limitation that hinders measurement accuracy: background noise. The background noise, which had not really received much attention from researchers until now, turned out to be much more significant than the accepted theory had posited.
To find out why, our researchers developed a method using very pure monocrystalline silicon resonators. They were able to identify two distinct kinds of background noise: the one in the theory, plus an unexpected one caused by a frequency variation intrinsic to the resonator. It is this second kind of noise that is detrimental to the performance of nanoresonators used as sensors.
The patented characterization protocol makes it possible not only to distinguish between the two types of background noise, but also to measure them. This advance will help researchers develop compensation mechanisms, ultimately leading to better resonator performance, and is applicable to all MEMS and NEMS microresonators that use resonant detection. These include gravimetric sensors, force sensors, and resonant transducers.