Method of rapidly interrogating elastic wave sensors

Abstract

A method of remotely interrogating a passive sensor, comprising at least one resonator, so as to determine the resonant frequency of said resonator, having a resonant frequency response defined by the design of said resonator, includes: a preliminary frequency-scan step for interrogating said resonator over a frequency range allowing for the rapid determination of a first resonant frequency (fr) of said resonator by detecting the amplitude of the response signal of said resonator; a first step of a first couple of interrogations of said resonator at a first frequency (f) and a second frequency (f) such that: f=fr−f/2 and f=fr+f/2, fbeing smaller than the width at half-maximum of the resonant frequency response defined by the design, allowing a first couple of amplitudes (Pf, Pf) of first and second reception signals to be defined; a second step of determining the amplitude difference (Δ(Pf−Pf)), said difference being signed; a third step allowing a first resonant frequency (fr), controlled by said signed amplitude difference, to be defined and having the formula fr=fr+K*[Δ(Pf−Pf)−Ca], where Ca is a control set-point and K is a constant; and the reiteration of the first, second and third steps comprising the definition of an (i+1)th resonant frequency (fr) from an ith resonant frequency (fr) having the formula: fr=fr+K*[Δ(Pf−Pf)−Ca], so as to obtain a determined resonant frequency (fr) such that the signed amplitude difference (Δ(Pf−Pf)) is equal to the control set-point (Ca).