EP4304008A1 - Passive wireless electronic component and reading system thereof - Google Patents

Abstract

The invention relates to a passive wireless electronic component (2) comprising at least one antenna (14), the or each antenna having an associated antenna frequency, and comprising at least one resonant microelectromechanical component, having a resonant frequency and connected to a contact point of said antenna, forming an antenna-resonator assembly adapted to receive an incident electromagnetic signal (S_i) comprising at least two frequencies and to emit a backscattered electromagnetic signal (S<sub >r</sub>). This passive wireless electronic component (2) is such that the or each antenna (14) comprises at least two microelectromechanical components (16, 18), MEMS, resonant with non-linear actuation, each of said MEMS components having a resonant frequency own mechanics belonging to a resonant frequency range, the resonant frequency ranges associated with two distinct MEMS components being disjoint.

Description

The present invention relates to a passive wireless electronic component and an associated reading system.

The invention lies in the field of passive electronic components, and more particularly passive electronic sensors and resonators.

By passive wireless electronic component we mean a component which does not include an energy source or a power rectifier. Such a component is also called a remotely powered component.

Sensors are, in a known manner, electronic or electromechanical components adapted to measure a physical quantity, for example temperature, pressure, humidity, etc.

Various types of remotely powered passive sensors have been developed, such sensors having the advantage of operating without an integrated energy source, which makes them usable in difficult environments, for example in installations operating at high temperatures. .

In the state of the art, there are several families of passive wireless sensors, in particular LC resonant circuit sensors, acoustic wave sensors and electromagnetic transduction sensors.

LC resonant circuit sensors are based on a capacitive sensor placed in series or parallel with an inductive loop, forming a resonant circuit. The resonant frequency of the circuit is modified by the variation in capacitance of the sensor as a function of the physical quantity to be measured. Such resonant circuit sensors have the disadvantage of a short reading distance, less than 10 cm.

Acoustic wave sensors include a surface acoustic wave sensor or SAW (Surface Acoustic Wave) or bulk acoustic wave sensor or BAW sensor, supplied with energy by an antenna, itself a powered TV. This type of sensor presents losses due to the double conversion between acoustic wave and electromagnetic wave, but also to the propagation of the acoustic wave in particular.

Electromagnetic transduction sensors associate a sensor with an antenna, which powers the sensor, the electromagnetic signal emitted (or backscattered) by the antenna in response to an incident electromagnetic signal being used to determine a value of measured physical quantity, the properties of the backscattered electromagnetic signal being modified depending on the sensor. Such transduction sensors electromagnetic have the disadvantage of the sensitivity of the antenna to the external environment. For example, the temperature can vary the permittivity of the substrate on which the antenna is printed, and modify the resonance frequency of the antenna, and consequently induce an inaccuracy in the measured value of the physical quantity considered.

The patent EP 2 478 636 B1 , entitled “Wireless MEMS sensor and its reading method” describes an electronic component, typically a sensor, comprising an assembly formed of an antenna and a microelectromechanical system (MEMS) type resonator connected to the antenna, which makes it possible to carry out a reading of a physical quantity measured as a function of the resonance frequency of the MEMS resonator, by an intermodulation technique. The MEMS resonator is characterized by two parameters, respectively the mechanical quality factor, the mechanical resonance frequency, the antenna having an electrical resonance frequency, and at least one of these three parameters is sensitive to the measured physical quantity. The intermodulation voltage makes it possible to generate an oscillation of the MEMS resonator in response to incident electromagnetic energy at two different frequencies. Although more robust to environmental conditions than an antenna, such a MEMS resonator can nevertheless also be impacted by environmental conditions, and therefore provide an imprecise physical quantity measurement. Furthermore, in this technology, the radio frequency antenna is a single antenna adapted to the MEMS resonator, in other words the limitation of a single MEMS resonator per antenna is imposed, which induces significant bulk when several sensors are required.

The invention aims to remedy the drawbacks of the state of the art by providing a passive electronic component of limited size and/or better precision for measuring physical quantities.

To this end, the invention proposes, according to one aspect, a passive wireless electronic component comprising at least one antenna, the or each antenna having an associated antenna frequency, and comprising at least one resonant microelectromechanical component, having a frequency resonance and connected to a contact point of said antenna, forming an antenna-resonator assembly adapted to receive an incident electromagnetic signal comprising at least two frequencies and to emit a backscattered electromagnetic signal. This electronic component is such that the or each antenna comprises at least two microelectromechanical components, MEMS, resonant with non-linear actuation, each of said MEMS components having a specific mechanical resonance frequency belonging to a range of resonance frequencies, the resonant frequency ranges associated with two distinct MEMS components being disjoint.

Advantageously, the proposed passive wireless electronic component comprises at least two microelectromechanical components, MEMS, resonant on the same antenna, the resonance frequencies of the two resonant MEMS components belonging to disjoint ranges, which makes it possible to differentiate the responses of the MEMS components resonant to an incident electromagnetic signal comprising selected frequencies.

The passive wireless electronic component according to the invention may also have one or more of the characteristics below, taken independently or in all technically conceivable combinations.

It comprises a number N of antennas, N being greater than or equal to two, each antenna comprising at least two microelectromechanical components, MEMS, resonant with non-linear actuation, each antenna having a specific antenna frequency, the antenna frequencies of two distinct antennas being different.

At least one of said at least two resonant MEMS components is a capacitive resonator.

At least one of said at least two resonant MEMS components is a resonant MEMS sensor whose resonant frequency varies as a function of a predetermined physical quantity.

The predetermined physical quantity is a physical quantity characteristic of an environment of the MEMS sensor resonant among temperature, air or gas pressure, humidity.

The passive wireless electronic component comprises a plurality of resonant MEMS sensors, each of said resonant MEMS sensors having a resonant frequency varying as a function of a distinct physical quantity, said passive electronic component being adapted to provide measurements of a plurality of distinct physical quantities.

The passive wireless electronic component comprises at least a pair of first and second resonant MEMS components, the first MEMS component being a resonant MEMS sensor whose resonant frequency varies as a function of a first physical quantity to be measured and as a function of at least one second physical quantity, the second MEMS component of said pair being a resonant MEMS sensor whose resonance frequency does not vary as a function of said first physical quantity, the resonance frequency of the second sensor varying as a function of said at least one second physical quantity.

Said at least two resonant MEMS components are connected in series or in parallel.

Said at least one antenna is produced in the form of a printed circuit on a substrate, and said MEMS components are produced on one or more silicon chips, each MEMS component being connected to an antenna element by wire bridging.

Said antenna and said at least two resonant MEMS components are implanted on the same silicon substrate.

Each resonant MEMS component is formed by a membrane positioned between two electrodes, of circular shape and having an associated radius.

According to another aspect, the subject of the invention is a system for reading a passive wireless electronic component of the type briefly described above, the system comprising a said passive wireless electronic component and a transmitting device and for analyzing electromagnetic signals, configured to transmit said incident electromagnetic signal to the passive electronic component and to receive and analyze the backscattered electromagnetic signal.

This reading system has advantages similar to those of the passive wireless electronic component.

According to one embodiment, the transmission and analysis device comprises a module generating an electrical signal and an antenna for transmitting and reading an incident electromagnetic signal, the transmission and reading antenna being also adapted to receive the electromagnetic signal backscattered by the antenna of the passive electronic component, the transmission and analysis device further comprising a signal processing module, configured to analyze the frequency characteristics of the backscattered electromagnetic signal.

• [Fig 1] la figure 1 est une illustration schématique fonctionnelle d'un système comprenant un composant électronique selon un mode de réalisation ;
• [Fig 2] la figure 2 illustre un premier mode de réalisation d'un composant électronique en vue de dessous ;
• [Fig 3] la figure 3 représente schématiquement en coupe les composants MEMS dans le premier mode de réalisation ;
• [Fig 4] la figure 4 représente un circuit électrique équivalent au composant électronique dans le premier mode de réalisation;
• [Fig 5] la figure 5 illustre schématiquement la variation de la capacité en fonction de la pression d'un capteur MEMS résonant à membrane ;
• [Fig 6] la figure 6 illustre des graphes de fonctionnement associés au capteur MEMS résonant à membrane ;
• [Fig 7] la figure 7 représente un graphe de variation de la puissance de la modulation du signal rétrodiffusé reçu en fonction des fréquences de résonance propres aux composants MEMS résonants dans le premier mode de réalisation du composant électronique ;
• [Fig 8] la figure 8 illustre un deuxième mode de réalisation d'un composant électronique ;
• [Fig 9] la figure 9 représente schématiquement en coupe une partie de la figure 8 illustrant un composant MEMS et sa connexion à un élément d'antenne ;
• [Fig 10] la figure 10 illustre un troisième mode de réalisation d'un composant électronique.

Other characteristics and advantages of the invention will emerge from the description given below, for information only and in no way limiting, with reference to the appended figures, among which:

• [ Figure 1 ] there figure 1 is a functional schematic illustration of a system comprising an electronic component according to one embodiment;
• [ Figure 2 ] there figure 2 illustrates a first embodiment of an electronic component in bottom view;
• [ Figure 3 ] there Figure 3 schematically represents in section the MEMS components in the first embodiment;
• [ Figure 4 ] there Figure 4 represents an electrical circuit equivalent to the electronic component in the first embodiment;
• [ Figure 5 ] there Figure 5 schematically illustrates the variation of capacitance as a function of pressure of a resonant membrane MEMS sensor;
• [ Figure 6 ] there Figure 6 illustrates operating graphs associated with the resonant membrane MEMS sensor;
• [ Figure 7 ] there Figure 7 represents a graph of variation of the modulation power of the received backscattered signal as a function of the resonance frequencies specific to the resonant MEMS components in the first embodiment of the electronic component;
• [ Figure 8 ] there figure 8 illustrates a second embodiment of an electronic component;
• [ Figure 9 ] there Figure 9 schematically represents in section part of the figure 8 illustrating a MEMS component and its connection to an antenna element;
• [ Figure 10 ] there Figure 10 illustrates a third embodiment of an electronic component.

There figure 1 schematically illustrates, by functional modules, a system 1 for reading a passive wireless electronic component according to one embodiment.

The system 1 comprises a passive wireless electronic component 2, several detailed embodiments of which will be described below, and a device 4 for transmitting and analyzing electromagnetic signals associated with the passive wireless electronic component.

The device 4 comprises a module 6 generating an electrical signal and a transmitting and reading antenna 8.

According to a variant not shown, the device 4 comprises two separate antennas, a transmitting antenna and a reading antenna.

The electrical signal is transformed into an incident electromagnetic signal S _i , also called an incident electromagnetic wave, emitted by the transmitting and reading antenna 8. The incident electromagnetic signal S _i comprises at least two frequencies, as described in more detail below.

The transmission and reading antenna 8 is also adapted to receive an electromagnetic signal S _r backscattered by the antenna 14 of the passive wireless electronic component 2.

The transmission and reading antenna 8 is connected to a signal processing module 10, implementing several signal processing functionalities including an analysis of the frequency characteristics of the backscattered electromagnetic signal S _r .

The device 4 further comprises a calculation module 12, which uses the frequency characteristics obtained to provide a result, for example a value of measured physical quantity or several values of measured physical quantities.

Modules 6, 10, 12 are electronic modules.

For example, module 12 is a calculation processor or a microcontroller.

The passive electronic component 2 is a wireless component comprising at least one antenna 14, to which are connected at least two microelectromechanical components, hereinafter called MEMS, which are resonant components with non-linear actuation each having a resonant frequency clean mechanics.

For example, the dimensions of the antenna 14 are millimetric, of the order of several millimeters in length and width or diameter depending on the antenna geometry. MEMS components have micro-metric dimensions.

For the same antenna, the mechanical resonance frequency of one of the MEMS components is strictly different from the mechanical resonance frequency of another MEMS component positioned on said antenna.

In other words, each MEMS component of the same antenna has a specific mechanical resonance frequency, called natural resonance frequency hereafter, belonging to a range of resonance frequencies, the ranges of resonance frequencies associated with two components Distinct MEMS being disjointed.

We call a resonant frequency range associated with a MEMS component a range of frequencies, [f_min, f_max], the natural resonance frequency f _m belonging to the range [f_min, f_max].

Two respective resonance frequency ranges, [f1_min, f1_max] and [f2_min, f2_max], are said to be disjoint when the smallest upper frequency limit of one of the frequency ranges, for example f1_max, is strictly less than the limit lower frequency, for example f2_min, of the other frequency range.

The antenna 14 is adapted to operate in reception in a frequency band called antenna bandwidth, [ F _a ± Δ], where F _a is the electrical resonance frequency of the antenna, called antenna frequency by the following.

For example, the antenna 14 is adapted to operate in a frequency band belonging to the frequency band between 300MHz and 3GHz, also called UHF band.

et donc $F_3\propto \frac{A_1{A}_2}{2}\cos 2\pi \left(f_1+f_2\right)+\frac{A_1{A}_2}{2}\cos 2\pi (f_1-$

$f_2)$

.By resonant component with non-linear actuation is meant a component whose actuation force is proportional to an electrical parameter (for example, an actuation voltage), more particularly proportional to a squared electrical parameter. The component will then be actuated at the intermodulated frequencies of the electrical actuation signal. For example, if the electrical signal S _e = A ₁ cos 2πf ₁ + A ₂ cos 2π f ₂ , the actuation force will be proportional to $S_e^2$

and so $F_3\propto \frac{{\mathrm{HAS}}_1{\mathrm{HAS}}_2}{2}\cos 2\pi \left(f_1+f_2\right)+\frac{{\mathrm{HAS}}_1{\mathrm{HAS}}_2}{2}\cos 2\pi (f_1-$

$f_2)$

.

In the embodiment illustrated in figure 1 , the passive wireless electronic component 2 comprises an antenna 14, to which are connected a first resonant MEMS component with non-linear actuation 16 and a second resonant MEMS component with non-linear actuation 18.

In one embodiment, MEMS components 16 and 18 are placed on antenna 14, each connected to antenna 14 at a contact point.

According to one embodiment, each of the resonant MEMS components 16, 18 is connected to the antenna 14 at the same contact point.

According to another embodiment, each of the resonant MEMS components 16, 18 is connected to the antenna 14 at a separate contact point.

The resonant MEMS components 16, 18 are connected in parallel or in series.

In one embodiment, the antenna is made on a substrate in the form of a printed circuit, and each MEMS component is made on a silicon chip, the MEMS components being connected to the antenna by means of wire bridging connections or " wire bonding” in English.

In an alternative embodiment, the antenna 14 and the connected MEMS components are made on the same silicon substrate.

In the example of the figure 2 , the passive wireless electronic component 2 includes an antenna 14.

In an alternative embodiment, the passive wireless electronic component 2 comprises a number N of antennas, N being greater than or equal to two, each comprising at least two microelectromechanical components, MEMS, resonant with non-linear actuation, each antenna having an antenna frequency of its own and which is different from the antenna frequency of each of the N-1 other antennas.

More generally, each antenna comprises a number P of resonant MEMS components with non-linear actuation, P being greater than or equal to 2.

In one embodiment, each of the MEMS components 16, 18 is a capacitive resonator.

In one embodiment, at least one of the resonant MEMS components is a resonant MEMS sensor whose mechanical resonance frequency varies as a function of a predetermined physical quantity, for example a capacitive MEMS sensor.

For example, the physical quantity is temperature, air or gas pressure, humidity.

In the reading system of a passive wireless electronic component 2, the incident electromagnetic signal S _i comprises at least two close frequencies, respectively a first frequency f _e and a second frequency f _e +f _m , these two frequencies being within the passband of the antenna 14. By adjusting the second frequency relative to the first frequency, one or other of the resonant MEMS components 16, 18 of the antenna is placed in resonance, this resonance modulating in amplitude the electromagnetic signal S _r backscattered by the antenna.

By studying, by scanning a set of frequencies f _m , the spectral characteristics of the backscattered electromagnetic signal, it is determined for which second frequency f _e +f _m of the incident electromagnetic signal S _i the amplitude of the modulation of the backscattered electromagnetic signal S _r varies the most. Thus, the device 4 detects the resonant frequency at which one of the resonant MEMS components of the antenna resonates.

The resonant frequency ranges of the MEMS components of the electronic component being disjoint, the reading makes it possible both to distinguish which resonant MEMS component of the antenna 14 is in resonance and to detect its resonance frequency.

When the resonant MEMS component is a resonant MEMS sensor, for example capacitive, whose mechanical resonance frequency varies with a given physical quantity, a value of the physical quantity considered is deduced by the calculation module 12.

Thus, advantageously, in one embodiment, the passive wireless electronic component 2 comprises a plurality of distinct capacitive MEMS sensors, the different sensors each having a mechanical resonance frequency varying with a distinct physical quantity. This makes it possible to measure a plurality of values of distinct physical quantities, while limiting the bulk of component 2.

A first embodiment of an electronic component 20 is described with reference to the figures 2 And 3 .

There figure 2 represents a view, called a bottom view, of the component 20, this component comprising a planar antenna 14 comprising two nested radiating loops 22, 24, and a set 30 of MEMS components.

The antenna 14 is for example produced in the form of a conductive track printed on a substrate 15, for example by PCB manufacturing technology.

The assembly 30 comprises, in this example, two MEMS components 26, 28, which are for example capacitive MEMS sensors of the circular membrane type, connected in parallel and represented schematically in the Figure 3 .

As illustrated in Figure 3 , each MEMS sensor 26, 28 is placed on a silicon substrate 33, and is connected to the radiating loop 24 via conductive tracks 32, 34, and bridging wires 35 (wire bonding).

By way of non-limiting example, the assembly 30 is formed on a substrate 33, of parallelepiped shape, with a rectangular base of millimetric dimensions, for example 1.1 mm in width and 1.7 mm in length.

In this embodiment, each of the two MEMS sensors 26, 28 is composed of a circular silicon membrane, separated from a fixed electrode by a vacuum cavity of given thickness g ₀ , preferably between 1 and 7 micrometers (µm), for example equal to 2.5µm.

In this example, the electronic component performs a pressure sensor functionality, the first MEMS sensor 26 being a sensor configured to measure the pressure, the second MEMS sensor 28 being a reference sensor, making it possible to refine the pressure measurement depending on of the temperature. The two MEMS sensors 26, 28, simply called sensors 26, 28 below, form a pair composed of a measurement sensor and a reference sensor.

The first sensor 26 is a capacitive pressure sensor, also sensitive to temperature.

The second sensor 28 of the embodiment of the figure 2 is a so-called reference sensor, of the same type as the first sensor 26, but whose mechanical resonance frequency does not vary as a function of the pressure.

For example in one embodiment, the membrane of this second sensor 28 is perforated, which makes it insensitive to pressure. The other characteristics of the second sensor, for example the surface of the membrane and the material from which the membrane is made, are identical to the characteristics of the first sensor.

An equivalent electrical circuit of the electronic component forming an antenna-sensor system of the figure 2 is illustrated in figure 4 .

The electrical operation of the antenna is considered equivalent to a series RCL circuit, the respective values of resistance R, capacitance C and inductance L being dependent on the electromagnetic characteristics of the antenna.

The first sensor 26 has a capacitance C ₁ (P,T) which varies as a function of the pressure and the temperature, and the second sensor 28 has a capacitance C ₂ (T) which varies as a function of the temperature.

THE figures 5 And 6 illustrate the operation of a MEMS membrane pressure sensor, for example of the first sensor 26, for a given temperature T.

The operation of a membrane pressure sensor is illustrated schematically in Figure 5 , for a given temperature.

The membrane 23 is compared to a capacitive component of capacity C ₀ formed between two electrodes 25 and 27 when the membrane 23 is at rest, the membrane 23 being placed on a cavity 38, empty or filled with air.

The external pressure (pressure of the environment of the sensor), schematized by arrows 29 on the Figure 4 , causes the membrane to deflect and modifies the capacitance C(P), where C(0)=C ₀ , between the two electrodes 25 and 27.

Associated operating graphs, in an operating example, are illustrated in the Figure 6 .

At a given temperature T, the resonance frequency of the first sensor 26 changes as a function of the pressure, between 0 bar and 1 bar.

An example of evolution is illustrated in graph G1 of the Figure 6 , in which the abscissa axis represents the pressure, with a variation between 0 bar and 1 bar, and the ordinate axis the resonance frequency of the membrane, between 1.810 MHz and 1.820 MHz.

The G2 graph of the Figure 6 illustrates the evolution of the capacitance C(P) as a function of time, the abscissa axis of the G2 graph representing the time between 0 and 2.5 µs, the ordinate axis the capacitance C(P) in picoFarads. The evolution of the capacitance is sinusoidal in response to the incident electromagnetic signal S _i .

The variation in capacitance results in a variation of the backscattered electromagnetic signal over time, making it possible to detect the resonance frequency of the sensor membrane.

In the embodiment of the figure 2 , the vibrations of the second sensor 28 are independent of pressure, but dependent on temperature.

The resonance frequency of the second sensor 28 is a reference resonance frequency f _ref dependent on the temperature T: $$f_{\mathit{ref}}\left(T\right)=f_{\mathrm{vs}}\left(0,T\right)$$

Where T designates the temperature, and f _c is the resonance frequency of the first sensor 26, dependent on pressure and temperature. In other words, the resonance frequency of the second sensor is equal to the resonance frequency of the first sensor at pressure equal to 0 bar and at the same temperature.

In an application example, the given temperature is the ambient temperature, for example T ₀ =20 °C. For example, the resonant frequency of the antenna is F _a =868 MHz.

For example, the first resonance frequency fc of the first sensor 26 varies in the resonance frequency range 1.81 to 1.82 MHz and the second resonance frequency of the second sensor 28 varies in the resonance frequency range 1.02 at 1.07 MHz.

In this example, the antenna-sensor system is designed so that at 868 MHz, and at a pressure equal to zero bar, the power of the backscattered electromagnetic signal sent by the antenna is maximum.

In one embodiment, the device 4 for transmitting and analyzing electromagnetic signals sends an electromagnetic signal S _i of frequency 868 MHz, modulated in amplitude with a modulation frequency f _m varying in the frequency range [ f _c ( 0 ,T ); f _c (1 ,T )].

The frequency range [ F _a + f _c (0, T ); F _a + f _c (1, T )] is included in the bandwidth of the antenna.

For each of the sensors, the electrical force created in the capacitance is proportional to the voltage across the sensor squared.

When the modulation frequency f _m is equal to the mechanical resonance frequency of one of the sensors, the force generated is of the form: $$F_e\left(t\right)=\frac{{\mathrm{VS}}_0}{2{\left(g_0-w\left(r\right)\right)}^2}{V}_0^2\left[\frac{2+M^2}{4}+\mathit{Msin}\left(2{\mathit{\pi f}}_{m}t\right)-\frac{M^2}{4}\mathrm{<figure-callout\; id="4"\; label="cos"\; filenames="imgf0001.png"\; state="\{\{state\}\}">cos</figure-callout>}\left(4{\mathit{\pi f}}_{m}t\right)\right]$$

Where C ₀ is the capacity at zero bar, g ₀ is the thickness of the cavity, w(r) is the deflection of a point r of the radius of the membrane due to the pressure, V ₀ is the tension between the terminals of the electrical circuit equivalent to zero bar, and M is the modulation index of the signal S _i .

By varying the frequency f _m over the frequency range [ f _c (0 ,T ); f _c (1 ,T )], we obtain a maximum of the power variation of the backscattered signal at two distinct frequency values, corresponding to the respective resonance frequencies, ie the first resonance frequency F ₁ =f _c (P,T ) of the first pressure sensor and the second resonance frequency F ₂ =f _ref (0,T) of the second sensor (reference sensor).

The variation of the power of the backscattered electromagnetic signal S _r as a function of frequency is illustrated in graph G ₃ of the Figure 7 , in which the y-axis represents the power of the backscattered electromagnetic signal and the x-axis the frequency.

In the example of the Figure 7 ; the resonance frequency of the second sensor (reference resonance frequency) F ₂ is lower than the first resonance frequency F ₁ of the first pressure sensor.

The second resonance frequency (or reference resonance frequency) provides information on the temperature of the environment in which the electronic component is placed.

Jointly taking into account the first resonance frequency of the first sensor and the reference resonance frequency makes it possible to obtain a more precise evaluation of the pressure, taking into account the temperature.

For example, the reference sensor is characterized beforehand in temperature, and the evolution of its mechanical resonance frequency as a function of the temperature is stored.

In addition, advantageously, two measurements of physical quantities are obtained, a temperature measurement and a pressure measurement.

There figure 8 illustrates a second embodiment of an electronic component 40, in which the electronic component comprises three resonant MEMS components with non-linear actuation, and more particularly three capacitive MEMS sensors of the circular membrane type.

Analogous to the figure 2 , there figure 8 illustrates a schematic view of the bottom of the electronic component 40.

In this second embodiment, the electronic component 40 comprises a planar antenna 14 comprising three nested loops.

The component 40 comprises three antenna loops, 42, 44, 46, each comprising a MEMS component 48, 50, 52, the MEMS components being for example capacitive MEMS sensors.

For example, component 40 comprises a first capacitive MEMS sensor 48 for measuring humidity, a second capacitive MEMS sensor 50 for measuring temperature, and a third capacitive MEMS sensor 52 for measuring pressure.

In this second embodiment, each capacitive MEMS sensor is connected at a separate contact point to the antenna 14, on a separate antenna loop.

Each of the capacitive MEMS sensors is connected, in one embodiment, analogously to the connection illustrated in Figure 3 .

There Figure 9 illustrates the connection of the MEMS sensor 48 to the antenna loop 42 in the embodiment of the figure 8 , the connection of the other MEMS sensors 50, 52 to the other antenna loops being similar.

A MEMS component 48, on a substrate 54, is connected to an antenna element 42 via conductive tracks 56, and wire bonding wires 58.

According to a variant, the first, second and third capacitive MEMS sensors 48, 50, 52 are for example connected in parallel or in series at the same contact point of the antenna 14.

Analogously, each of these capacitive MEMS sensors has a specific resonant frequency, belonging to a specific resonant frequency range, the resonant frequency ranges of three sensors being disjoint.

Thus, three distinct physical quantities are measurable, by applying the measurement method described above with reference to the figure 2 , for example temperature, humidity and pressure.

Of course, temperature, humidity and pressure are examples of measurable physical quantities, the invention being applied in a similar manner to the measurement of other physical quantities.

In one embodiment, the antenna 14 is produced by printing on a substrate via printed circuit manufacturing technology, and each MEMS component is produced on a silicon substrate.

In another embodiment, the antenna 14 and the plurality of capacitive MEMS sensors are implanted on the same substrate, for example a silicon substrate, using microsystems manufacturing technologies. The connection between each capacitive MEMS sensor and the antenna is then made with conductive tracks.

There Figure 10 illustrates an example of a third embodiment of a passive wireless electronic component 60, illustrated in a “top” view.

In this embodiment, called an antenna array, the electronic component comprises N antennas, N=4 in the example illustrated, referenced 62 ₁ , 62 ₂ , 62 ₃ , 62 ₄ , the generic reference 62 _i being used for indicate any of these antennas.

Each antenna 62 _i comprising two nested loops 64 _i , 66 _i , and two distinct resonant MEMS components, respectively 68 _i , 70 _i , each respective MEMS component being connected to one of the antenna loops and having its own resonant frequency , belonging to a resonant frequency range, the resonant frequency ranges being disjoint for two distinct resonant MEMS components 68 _i , 70 _i .

In this third embodiment each antenna 62 _i has its own antenna frequency Fa_i, the resonance frequencies of two separate antennas being strictly different.

In this case, the reading, for example the detection of the resonance of a given resonant MEMS component 64 _i , 66 _i, is done using the resonance frequency of the antenna Fa_i and its own resonance frequency F1_i, F2_i .

The antenna frequencies Fa_i being all distinct, it is possible to provide, in a variant, resonant MEMS components with the same resonant frequencies associated with distinct antennas, ie F1_i=F1_j and F2_i=F2_j for i different from j.

This third embodiment is particularly suitable, using resonant MEMS sensors, for the study of localized variations of the same physical quantities on a surface.

In a variant, the resonant MEMS components of the third embodiment are capacitively actuated MEMS resonators, the resonance of one of these resonators making it possible to identify the associated antenna.

The embodiments of the invention given by way of example above comprise a planar antenna with nested loops.

Alternatively, other types of antenna can be used, in particular planar antennas having a different geometry, for example patch or dipole, or a non-planar antenna, for example a horn antenna.

The invention has been described with resonant MEMS components of the vibrating membrane type. Alternatively, other types of resonant MEMS components can be used, for example a vibrating beam.

Thus, according to a variant, resonant MEMS components of various geometries, for example with a vibrating membrane and a vibrating beam, are integrated on the same antenna.

According to another variant, the vibration nonlinearity of the MEMS component is obtained by an external component, for example a diode.

Advantageously, an electronic component according to the invention is remotely powered and has reduced bulk, while allowing the measurement of several physical quantities and/or an improvement in the precision of the measurement of one or more of the physical quantities measured.

Claims (13)

Passive wireless electronic component comprising at least one antenna, the or each antenna having an associated antenna frequency, and comprising at least one resonant microelectromechanical component, having a resonant frequency and connected to a contact point of said antenna, forming an antenna-resonator assembly adapted to receive an incident electromagnetic signal comprising at least two frequencies and to emit a backscattered electromagnetic signal, characterized in that the or each antenna (14, 62 ₁ , ..., 62 ₄ ) comprises at least two microelectromechanical components (16, 18, 26, 28,48, 50, 52, 68 ₁ -68 ₄ , 70 ₁ -70 ₄ ), MEMS, resonants with non-linear actuation, each of said MEMS components having a specific mechanical resonance frequency belonging to a resonant frequency range, the resonant frequency ranges associated with two distinct MEMS components being disjoint. Component according to claim 1, comprising a number N of antennas, N being greater than or equal to two, each antenna comprising at least two microelectromechanical, MEMS, resonant components with non-linear actuation, each antenna having its own antenna frequency, the antenna frequencies of two separate antennas being different. Component according to claim 1 or 2, wherein at least one of said at least two resonant MEMS components is a capacitive resonator. Component according to any one of claims 1 to 3, in which at least one of said at least two resonant MEMS components is a resonant MEMS sensor whose resonance frequency varies as a function of a predetermined physical quantity. Component according to claim 4, in which said predetermined physical quantity is a physical quantity characteristic of an environment of the MEMS sensor resonant among temperature, air or gas pressure, humidity. Component according to any one of claims 4 or 5, comprising a plurality of resonant MEMS sensors, each of said resonant MEMS sensors having a resonant frequency varying as a function of a physical quantity distinct, said passive electronic component being adapted to provide measurements of a plurality of distinct physical quantities. Component according to any one of claims 4 to 6, comprising at least a pair of first and second resonant MEMS components, the first MEMS component being a resonant MEMS sensor whose resonant frequency varies as a function of a first physical quantity to be measured and as a function of at least a second physical quantity, the second MEMS component of said pair being a resonant MEMS sensor whose resonance frequency does not vary as a function of said first physical quantity, the resonance frequency of the second sensor varying as a function of said at least one second physical quantity. Component according to any one of claims 1 to 7, wherein said at least two resonant MEMS components are connected in series or in parallel. Component according to any one of claims 1 to 8, in which said at least one antenna is produced in the form of a printed circuit on a substrate, and said MEMS component is produced on one or more silicon chips, each MEMS component being connected to an antenna element by wire bridging. Component according to any one of claims 1 to 8, in which said antenna and said at least two resonant MEMS components are implanted on the same silicon substrate. Component according to claim 9 or 10, in which each resonant MEMS component is formed by a membrane positioned between two electrodes, of circular shape and having an associated radius. System for reading a passive electronic component, comprising a passive electronic component according to claims 1 to 11 and a device for transmitting and analyzing electromagnetic signals, configured to transmit said incident electromagnetic signal to the passive electronic component and to receive and analyze the backscattered electromagnetic signal. System according to claim 12, in which said transmission and analysis device (4) comprises a module (6) generating an electrical signal and an antenna (8) for transmitting and reading an incident electromagnetic signal (S _i ), the antenna (8) transmission and reading being also adapted to receive the electromagnetic signal (S _r ) backscattered by the antenna (14) of the passive electronic component (2,20, 40, 60), the transmission device (4) and the analysis further comprising a signal processing module (10), configured to analyze the frequency characteristics of the backscattered electromagnetic signal (Sr).

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