The array could sense either ten different species, or a single species with ten times the sensitivity. The same principle could be used to study other types of intermolecular interaction. 5 Such experiments would require about twice the magnetic force currently used in the FABS device. Waving a small magnet over the cantilever produced a measurable deflection, as detected with an optical lever. FABS electronic schematic showing reference cantilever and lock-in detection.
External vibrations cause both the signal and the reference cantilever to vibrate.
Without the reference cantilever, such vibrations might, in severe conditions, overwhelm the minute forces exerted by the beads. Subtracting the reference from the signal helps reduce such interference. The measured noise of the prototype is also 12.5 pN rms. At present, we signal average for 102.4 s to obtain each FABS reading. Measured noise of the prototype FABS as a function of frequency.