Besançon, France
Besançon, France

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A surface elastic wave resonator comprises a piezoelectric material to propagate the surface elastic waves and a transducer inserted between a pair of reflectors comprising combs of interdigitated electrodes and having a number Nc of electrodes connected to a hot spot and an acoustic aperture W wherein the relative permittivity of the piezoelectric material is greater than about 15, a product of NcW/fa for the transducer being greater than 100 mMHz^(1), where fa is the antiresonance frequency of the resonator. A circuit comprises a load impedance and a resonator according to the invention and having an electrical response manifesting as a peak in the coefficient of reflection S_(11 )at a frequency of a minimum value of the parameter S_(11 )that is lower than 10 dB, the antiresonance peak of the resonator being matched to the impedance of the load.

Senseor, University of Franche Comte and French National Center for Scientific Research | Date: 2010-10-08

A transponder including a first resonator and a series of one or more second resonators with coupling of evanescent waves exhibiting at least one first resonant mode and one second resonant mode, said first resonator being connected via a first port, to a first means allowing an interrogation, wherein said second resonators are connected via at least one second port, to at least one variable load element capable of modifying coupling conditions of the resonant modes and consequently a response measured on said first port.

Senseor and French National Center for Scientific Research | Date: 2011-04-05

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_(0)) 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_(11)) and a second frequency (f_(21)) such that: f_(11)=fr_(0)f_(m)/2 and f_(21)=fr_(0)+f_(m)/2, f_(m )being smaller than the width at half-maximum of the resonant frequency response defined by the design, allowing a first couple of amplitudes (Pf_(11), Pf_(21)) of first and second reception signals to be defined; a second step of determining the amplitude difference ((Pf_(11)Pf_(21))), said difference being signed; a third step allowing a first resonant frequency (fr_(1)), controlled by said signed amplitude difference, to be defined and having the formula fr_(1)=fr_(0)+K*[(Pf_(11)Pf_(21))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_(i+1)) from an ith resonant frequency (fr_(i)) having the formula: fr_(i+1)=fr_(i)+K*[(Pf_(1i)Pf_(2i))Ca], so as to obtain a determined resonant frequency (fr_(i+1)) such that the signed amplitude difference ((Pf_(1i)Pf_(2i))) is equal to the control set-point (Ca).

Friedt J.-M.,SENSeOR
2013 Joint European Frequency and Time Forum and International Frequency Control Symposium, EFTF/IFC 2013 | Year: 2013

The flexibility, reconfigurability and stability of software defined radio yield an attractive alternative to the analog strategy of probing acoustic transducers acting as passive sensors probed through a wireless link or to phase noise characterization of oscillators. However, developing processing blocks is a time consuming activity, yet metrology applications require a dedicated understanding of each processing step. We consider GNURadio as a means of exploiting opensource software as an optimum tradeoff between software re-usability yet compatible with an audit for assessing performance. This signal processing environment is demonstrated on two practical examples, FMCW probing of acoustic delay lines acting as sensors, and quartz tuning fork characterization. Both examples are considered as introductory setups for training and teaching yet a suitable environment for research activities. © 2013 IEEE.

A method of interrogating a surface acoustic wave differential sensor formed by two resonators is provided, wherein the method allows the measurement of a physical parameter by determination of the difference between the natural resonant frequencies of the two resonators, which difference is determined on the basis of the analysis of a signal representative of the level of a signal received as echo of an interrogation signal, for a plurality of values of a frequency of the interrogation signal in a domain of predetermined values; the analysis can be based on the cross-correlation of the said signal representative of the level according to a splitting into two distinct frequency sub-bands. An advantage is that it may be implemented in a radio-modem.

A method for interrogating an elastic wave device includes probing the response of a piezoelectric resonant device at a single frequency alternately on either side of a previously determined first resonance frequency, to characterize this resonance frequency characteristic of the measured physical quantity, by correlating this single measurement with a previously performed measurement.

A method of interrogating sensors of SAW type, which allows notably the gathering of physical measurements of parameters carried out by SAW sensors, the method for gathering the measurement of an SAW sensor comprising a first step of generating and emitting an electromagnetic signal corresponding to the dilated time-reversal of a dilation coefficient k, of an impulse response signature which is characteristic of the SAW sensor, a second step of gathering a signal received as echo originating from the SAW sensor, a third step of determining a maximum of cross-correlation of the signal received as echo during the second step, the first step being applied with a set of values of the dilation coefficient k in a determined domain, the measurement of a physical parameter then being determined by the dilation coefficient k for which the power or the amplitude of the signal gathered as echo is a maximum.

A method of collective fabrication of remotely interrogatable sensors, each sensor comprising at least one first resonator and one second resonator, each resonator comprising acoustic wave transducers designed such that they exhibit respectively a first and a second operating frequency, is provided. The method comprises the fabrication of a first series of first resonators (RT_(1i)) exhibiting a first resonant frequency at ambient temperature (f_(1i)) and a first static capacitance (C_(1i)); the fabrication of a second series of second resonators (RT_(2j)) exhibiting a second resonant frequency at ambient temperature (f_(2j)) and a second static capacitance (C_(2j)); a series of electrical measurements of the set of the first series of first resonators and of the set of the second series of second resonators, so as to determine first pairs (f_(1i), C_(1i)) and second pairs (f_(2j), C_(2j)) of resonant frequency and of capacitance of each of the first and second resonators; and a series of matchings of a first resonator (RT_(1i)) and of a second resonator (RT_(2j)) according to the aggregate of the following two criteria: the dispersion in the difference in resonant frequency (f_(1i)f_(2j)) is less than a first threshold value (Sf) and the dispersion in the difference in static capacitance (C_(1i)C_(2j)) is less than a second threshold value (Sc).

A pressure and temperature sensor comprising comprises at least a first resonator of the SAW type comprising a piezoelectric substrate, thinned at least locally, of the membrane type, a second resonator of the SAW type comprising a piezoelectric substrate and a third resonator of the SAW type comprising a piezoelectric substrate, characterized in that the first, the second and the third resonators are respectively on the surface of first, second and third individual piezoelectric substrates, each of the individual substrates being positioned on the surface of a common base section, locally machined away under said first resonator in such a manner as to liberate the substrate from said resonator so as to render it operational for the measurement of pressure. A method of fabrication for such a sensor is also provided.

A system comprises a cavity being reflecting for RF waves and comprises at least one acoustic wave sensor exhibiting a resonance frequency band, coupled to a sensor antenna; and an interrogation/reception device for the sensor. The interrogation/reception device comprises: means for transmitting/receiving an RF signal transmitting within an interrogation frequency band comprising the resonance frequency band of the sensor; at least a first transmission/reception antenna and a second transmission antenna/reception, positioned within the cavity; means for dividing the signal into at least a first RF signal and a second RF signal, the first signal being transmitted to the first transmission/reception antenna and the second signal being transmitted to the second transmission/reception antenna; means for creating a phase-shift between the first RF signal and the second RF signal; means for analysing the power level of the received signal. An interrogation method used in the system is also provided.

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