s should accumulate in tmeas = Q / 2 nspring ~ 2 microsec and should be detectable by looking at magnitudes of forces. Interestingly, an SPM microprobe of circular cross-section and exponential profile with a 0.1 nm2 tip has been proposed that could also reach ~proton mass detection sensitivity at room temperature and 1 atm pressure with an eigenmode frequency of 10 GHz;1195 an electrically-driven carbon nanotube-based resonant-beam balance demonstrated ~10-17 kg (~1010 proton or ~0.01 micron3 mass) sensitivity in 1999.3023
Existing surface acoustic wave (SAW) devices458 are chemical sensors that can measure areal mass densities as small as 80 picogram/cm2, or 0.01 N2 molecule per nm2 of surface, though current devices are limited to ~micron2 areas. A proposed quartz microresonator microbalance could detect a 10-6 molecular monolayer,459 the equivalent of 5 x 10-9 molecule per nm2. Detection of ~400 million protons using an MRFM vibrating rod ~60 nm thick was demonstrated by Rugar3256 in 1998.
Last updated on 17 February 2003