Patent ID: 7549338

Claim:
A method for sensing at least one or presence of, and concentration of, a target molecule that may be present in a fluid, the method comprising: providing a first thin beam, having a strip of a selected chemical substance of a selected length D, oriented substantially parallel to a longitudinal axis of the beam, on at least one surface of the beam, where the selected chemical substance binds to a selected target molecule; providing a first resonant frequency ω1 of vibration of the first beam and the at least one strip; allowing a selected test fluid, which may contain a target molecule in an unknown concentration, to flow past the first beam for a selected time duration Δt, to provide a modified first beam; providing an estimated second resonant frequency ω2(est) of vibration of the modified first beam; providing a measured second resonant frequency ω2(meas) of vibration of the modified first beam, where ω2(est) is substantially different from ω1; when the frequency ω2(meas) is substantially equal to ω1, interpreting this condition as indicating that the target molecule is not present in the fluid; and when the frequency ω2 (meas) is substantially equal to ω2(est), interpreting this condition as indicating that the target molecule is present in the fluid.