Method for detecting a perturbation by hysteretic cycle using a nonlinear electromechanical resonator and device using the method

A method for detecting a perturbation with respect to an initial state, of a device comprising at least one resonant mechanical element exhibiting a physical parameter sensitive to a perturbation such that the said perturbation modifies the resonance frequency of the said resonant mechanical element, said method comprising:

• excitation of the resonant mechanical element making it possible to cause the said resonant mechanical element to vibrate in a domain of non-linear amplitude response at a vibration frequency Ω, the said amplitude and the said frequency being linked by an initial function f0 (Ω), the said perturbation generating a measurement function fM (Ω);
• and
• detection and the analysis of the variations of amplitude of vibrations of the said mechanical element between an amplitude of the function f0 (Ω) and an amplitude of the function fM (Ω) resulting from the excitation;
• wherein the function f0 (Ω) exhibiting a bifurcation frequency Ωlim, corresponding to a change of increase and of decrease of the frequency as a function of amplitude and possessing at least one unstable frequency band (BINS) in which there exist at least two stable amplitudes for one and the same frequency, and at least one stable frequency band (BS) in which a single stable amplitude corresponds to a single frequency, the excitation step is carried out:
• at a variable vibration frequency within a frequency band defined by a minimum frequency Ωmin and a maximum frequency Ωmax and
• according to at least one frequency cycle centred on a central frequency Ωop, one of the said minimum or maximum frequencies being situated in the stable frequency band of the said initial function, the other maximum or minimum frequency being situated in the unstable frequency band.