WO2015107455A1 - Analyse de matériaux par spectroscopie hyperfréquence - Google Patents

Analyse de matériaux par spectroscopie hyperfréquence Download PDF

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Publication number
WO2015107455A1
WO2015107455A1 PCT/IB2015/050246 IB2015050246W WO2015107455A1 WO 2015107455 A1 WO2015107455 A1 WO 2015107455A1 IB 2015050246 W IB2015050246 W IB 2015050246W WO 2015107455 A1 WO2015107455 A1 WO 2015107455A1
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WO
WIPO (PCT)
Prior art keywords
waveguide
control unit
gain
container
transmitting antenna
Prior art date
Application number
PCT/IB2015/050246
Other languages
English (en)
Inventor
Luigi Ragni
Annachiara BERARDINELLI
Chiara CEVOLI
Matteo FILIPPI
Eleonora IACCHERI
Aldo Romani
Original Assignee
Alma Mater Studiorum - Università di Bologna
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alma Mater Studiorum - Università di Bologna filed Critical Alma Mater Studiorum - Università di Bologna
Publication of WO2015107455A1 publication Critical patent/WO2015107455A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more

Definitions

  • the patent application WO2011/064770 discloses a system for determining milk components using dielectric spectrography. Milk is inserted into a sampling cell containing two electrodes to which a variable frequency voltage is applied. The system provides for measuring the impedance between the electrodes by applying voltages at least at three different frequencies.
  • This system is suitable for working on liquid materials and within a frequency range not exceeding 1.4 GHz.
  • the system uses a rectangular waveguide wherein a container is placed with the material to be analyzed.
  • the container is placed between two antennas, a transmitting one and a receiving one, connected to a sweeper (device generating a frequency comb) and to a spectrum analyzer of the professional type respectively.
  • a sweeper device generating a frequency comb
  • a spectrum analyzer of the professional type respectively.
  • the object of the present invention to provide a spectroscopy system based on the dielectric behavior of materials that has a compact size, such to improve its transportability, that is easy to use and that has a low cost.
  • Another object of the present invention is to provide a measuring system usable and effective for different types of materials.
  • the system comprises a waveguide, preferably rectangular, provided with a closable opening to access the inside of the guide where there is provided a holder for a container intended to contain a material to be analyzed, a transmitting antenna and a receiving antenna placed at two opposite sides of the holder.
  • the system further comprises a radio frequency signal generator operatively connected to the transmitting antenna for generating a radio signal in the waveguide.
  • the system further comprises a gain and phase comparator connected to the receiving antenna and the transmitting antenna, in order to provide the control unit with the gain and phase introduced by the path into the waveguide on the signal transmitted by the transmitting antenna.
  • control unit is configured to control the signal generator in such a way as to generate a sinusoidal signal with variable frequency within a given range of measurement.
  • the control unit stores the gain and phase data measured at said different frequencies and send them to a computer.
  • Such data are processed by multivariate or non multivariate statistical systems or by another processing algorithm in order to obtain a predictive determination about the chemical-physical characteristics of the material.
  • Such data can also be compared with information stored in a database, such to allow, for example, the analyzed material to be identified or to allow the qualitative correspondence thereof within specific tolerances.
  • USB connection through which the system can be connected to a computer outside the measuring system, for calibration procedures, the launch of the acquisition, the transfer and processing of the data acquired by the measuring system.
  • USB connection is the only one for the connection of the system to the external environment, such to reduce costs for producing the system.
  • system can locally provide for the data storage functions, by providing an input interface and a display operatively connected to the control unit for displaying information associated to the measurements performed.
  • the system provides an input interface and a display and it locally provides for the storage, analysis, comparison of the measured data with those of a database, a local one as well, by providing the results of the determinations without the need of external computers.
  • Fig. 1 is a block diagram of a measuring system according to the present invention.
  • Fig. 2 is a circuit detail of the system of figure 1
  • Figs. 5a and 5b are alternative solutions for positioning a container in the system of figure 3.
  • Fig. 7 is two graphs showing the measurements obtained by the system of figure 1. DETAILED DESCRIPTION OF THE INVENTION
  • gain of a transfer function means the ratio between the amplitudes of output and input signals; therefore a gain may be positive (amplification) or negative (attenuation).
  • FIG 1 shows a system for measuring chemical-physical parameters of food and non-food substances.
  • the system 1 comprises a waveguide 2 that in the preferred example of figure 1 is a rectangular waveguide.
  • the guide can obviously have also other shapes, for example it may be a cylindrical guide, however the rectangular shape is the preferred one.
  • a transmitting antenna 20 Inside the waveguide 2 there are provided a transmitting antenna 20, a receiving antenna 21 and a sample holder 22 for a container 23, intended to hold the material, or a test sample made of solid material to be analyzed.
  • the antennas 20 and 21 are preferably made with a body of brass and more preferably are golden, while the container 23 and the relevant holder are made of non-metallic materials, particularly glass (which is preferred above all in case of highly corrosive materials), or of low permittivity plastic material (preferably with a dielectric constant ⁇ 2 and loss factor ⁇ 5xl0 -4 ), such not to interfere with the behavior of the waveguide 2.
  • the latter has an aperture 24 closable by means of a removable lid 25.
  • the aperture 24 and the lid 25 are made in such a manner that, when the lid 25 is in position and it closes the aperture 24, the face of the lid facing the inside of the guide 20 forms a substantially continuous plane with the inner surface of the guide, such that the clearance between the lid and the aperture does not affect the performances of the guide.
  • the waveguide 2 ends by a pyramidal end 26 intended to limit the reflection phenomena.
  • the transmitting antenna is placed inside the waveguide 2 such that an electromagnetic wave propagates inside the waveguide in the dominant mode (transverse electric) TEio with an electric field lying in a plane orthogonal to the development plane of the guide.
  • the system 1 comprises a measuring unit 3 comprising a control unit 30, particularly a microcontroller, that controls a signal generator 31 coupled with the transmitting antenna 20 by means of a suitable connector 201.
  • the signal generator 31, in the preferred embodiment shown in figure 1 comprises a voltage controlled oscillator (VCO) 310 that provides to the antenna 20 a voltage signal VRF with a frequency dependent on the modulus of voltage VIN that controls it.
  • VCO voltage controlled oscillator
  • control unit 30 generates a pulse train which is converted by the D/A converter 312 (for example an integrated MCP4822) into a voltage that, suitably amplified by a gain predetermined by the amplifier 311, controls the VCO 310.
  • D/A converter 312 for example an integrated MCP4822
  • the control unit 30, by changing the pulse train provided at the output 301, thus changes the voltage provided to the VCO and it adjusts the frequency of the radio signal generated by the antenna 20.
  • the waveguide 2 in order to operate within the frequency range 1.6-2.7 GHz, is 96mm in width (the dimension is shown in fig.4, by the reference “w", it has a height 'h' equal to 46 mm and it is long 477 mm) the dimension is shown in fig.l by reference ⁇ ).
  • the transmitting antenna 20 is placed at a distance 'a' of 62 mm from the wall opposite to that where the end 26 is mounted, while the receiving antenna is placed at a distance 'b' of 109 mm from the transmitting antenna 20.
  • the distances are taken with reference to the centre of the antennas, that for example may be cylindrical antennas with a diameter ⁇ of 8 mm and an overall height 'la' of 24 mm (of which 20 mm of radiant body, ⁇ ' and 4mm of the supporting rod); in this case the distances 'a' and 'b' are taken with respect to the axis of rotation of the cylinder.
  • the end 26 is selected with a pyramidal shape and it extends inside the guide for a distance 'f equal to 232mm.
  • the holder 22 is secured to the base of the guide 2 such to place the container 23 or the solid test sample in the middle of the two antennas 20 and 21. In the preferred example of figure 2, the container has a height of 44 mm, such to arrive near to, but not touching, the upper wall of the waveguide 2.
  • the ramp amplifier 311 comprises an operational amplifier receiving at the inverting input the output voltage from the D/A converter 312 and wherein the inverting input is connected at ground by a resistor Rl and to the output by a resistor R2 such to amplify the signal coming from the D/A converter 312 according to what required by the voltage controlled oscillator to produce the desired frequency change (e.g. 1.6- 2.7 GHz).
  • the VCO is a discrete component, for example a VCO produced by Mini-Circuits® , ROS-2800-719+ or ZX95-2800+ model.
  • the VRF signal (at the output of the VCO) can be sent through a "T" connector both to the antenna 20 and to the input of the comparator 32, or as an alternative, in order to limit the reflections, to a "power splitter” (PSL) that distributes the signal (Tx) between the antenna 20 and the input (VINA) of the comparator.
  • PSL power splitter
  • Appropriate attenuators possibly have to be provided in order to limit the voltages within the nominal input values of the comparator.
  • the comparator 32 is a gain and phase comparator, for example a AD8302 comparator by AnalogDevices®.
  • the comparator 32 is connected to the transmitting antenna 20 and to the receiving antenna 21 and it receives as input the signals provided by the antenna 20 and those received by the antenna 21.
  • the output signals from the comparator 32 are two analog signals, which are properly amplified by the amplifier 33 in order to be then converted into digital signals, by means of the sampling operation performed by the control unit 30.
  • the control unit 30 changes the frequency of the oscillator through the D/A converter 312 and the ramp amplifier 311, thus generating different frequencies that are caused to change within a range preferably from 1.6 to 2.7 GHz. For each frequency generated by the oscillator 310, the control unit 30 receives the gain and phase data measured at the different frequencies.
  • the control unit 30 processes the gain and phase signals received from the amplifier 33 and it generates an output, for example, through a USB port to which a computer is connected.
  • the gain and/ or phase data related to the frequencies can be processed by an electronic sheet and displayed on a Gain-Frequency graph or in a Phase- Frequency graph of the type shown in figure 7. This figure shows different curves measured by the system of the present invention. The curves are obtained by interpolation of the measured data.
  • the control unit can be provided with an interpolation system such to provide output signals representative of a gain/ frequency curve or a phase/ frequency curve.
  • Figure 7 shows the measurements performed on different glucose solutions in water, for example lg of glucose dissolved in 99g of water.
  • the gain and phase data are preferably downloaded on a computer, through a suitable interface program resident in the computer, and are processed therein by suitable algorithms and statistical techniques known per se (comparisons, linear and non-linear regressions, partial least square regression, neural networks etc.) such to provide, on the basis of preventive calibration processes (composing a database) a predictive determination of the characteristic of interest of the material under examination.
  • the gain and phase data measured at different frequencies are compared with those stored in the (local or remote) database, in order to come to an estimation of the characteristic of interest of the analyzed material; for example the system may generate information indicative of the fact that a cheese or a wood have a specific seasoning, a coffee has a specific humidity, a solution contains a specific percentage of alcohols, is characterized by a given acidity or salinity etc, a compound contains a given amount of a given pigment, a general material meets specific qualitative requirements within specific tolerances.
  • Figure 3 shows a particularly compact embodiment of the measuring system of figure 1.
  • the waveguide 2 and the measuring unit are both housed in the same metal housing 100.
  • the housing 100 is made of metal and one or more of its walls is in common with the guide 2, namely at least one wall of the housing 100 is a wall of the waveguide 2.
  • Figure 4 allows also appreciating the positioning of the holder 22, that is fixed between the two antennas 20 and 21.
  • the holder 22 serves for allowing the container or the solid test sample to be properly positioned between the antennas, therefore it is preferably glued (e.g. by epoxy or acrylic glue) to the bottom wall of the waveguide 2.
  • the container is provided with an adaptive base 230 with a shape complementary to that of the seat 220 of the holder 22.
  • the container and the adaptive base preferably are a single body.
  • the container can have a cylindrical shape with diameter of 23mm and can be placed at the centre of a circular base 230 with a diameter of 50 mm intended to fit into the seat 220 of the holder 22.
  • Figure 6 shows a solution alternative to figure 5a for positioning the container 23, useful for accommodating both containers and cylindrical tests samples of solid material.
  • a connecting ring 221 is provided whose outer shape is complementary to that of the seat 220 of the holder 22, while the inner profile of the ring has a shape complementary to that of the container 23, that thus can fit into the central hole of the ring.
  • the connecting ring 221 has an external diameter DE equal to that of the seat 220 of the holder 22 and an inner diameter Din equal to the diameter of the cylindrical container 23.
  • DE outer diameter
  • Din inner diameter
  • Figures 6a, 6b, 6c show connecting rings 221 all with the same outer diameter De (e.g.50mm) and different inner diameter Din (e.g. 23 mm for fig.6a, 29mm for fig. 6b, 34mm for fig.6c).
  • the container 23d has an outer diameter with a dimension equal to that of the seat 220 of the holder 22 and therefore connecting rings for housing the container 23d are not necessary.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Measurement Of Resistance Or Impedance (AREA)

Abstract

La présente invention concerne un système pour la mesure de paramètres liés aux propriétés diélectriques d'un matériau, utile pour déterminer des caractéristiques physico-chimiques du matériau. Le système comprend un guide d'onde, de préférence rectangulaire, pourvu d'une ouverture pouvant être fermée pour accéder à l'intérieur du guide où il est disposé un support d'échantillon pour contenir et loger un matériau à analyser, une antenne d'émission et une antenne de réception placées à deux côtés opposés du support. Le système comprend en outre un générateur de signal de radiofréquence fonctionnellement raccordé à l'antenne d'émission pour générer un signal radio dans le guide d'onde. Ensuite, le système comprend un comparateur de gain et de phase connecté à l'antenne de réception et l'antenne d'émission, pour fournir à l'unité de commande le gain et la phase introduits par le trajet dans le guide d'onde sur le signal émis par l'antenne d'émission. L'unité de commande permet en outre de transmettre des données pour le traitement requis.
PCT/IB2015/050246 2014-01-15 2015-01-13 Analyse de matériaux par spectroscopie hyperfréquence WO2015107455A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI2014A000039 2014-01-15
ITMI20140039 2014-01-15

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WO2015107455A1 true WO2015107455A1 (fr) 2015-07-23

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111954806A (zh) * 2018-04-17 2020-11-17 Ubt有限责任公司 用于材料的介电不连续性的微波测量的设备
US11397159B1 (en) 2018-08-31 2022-07-26 Byte Nutrition Science Incorporated Systems, devices and methods for analyzing constituents of a material under test

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6147503A (en) * 1998-05-08 2000-11-14 The United States Of America As Represented By The Secretary Of Agriculture Method for the simultaneous and independent determination of moisture content and density of particulate materials from radio-frequency permittivity measurements
WO2002046357A1 (fr) 2000-10-26 2002-06-13 The Trustees Of Princeton University, Princeton University Procede et appareil de spectroscopie dielectrique de solutions biologiques
WO2005043142A2 (fr) * 2003-10-24 2005-05-12 Troxler Electronic Labs, Inc. Procedes et dispositifs de mesurage a micro-ondes de la densite d'un materiau de chaussee
EP1712900A1 (fr) 2005-04-15 2006-10-18 M. Alessandro Manneschi Dispositif d`analyse de la composition du contenu d`un recipient
WO2011064770A2 (fr) 2009-11-25 2011-06-03 S.A.E Afikim Milking Systems Agricultural Cooperative Ltd. Procédé et dispositif d'analyse spectroscopique diélectrique du lait

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6147503A (en) * 1998-05-08 2000-11-14 The United States Of America As Represented By The Secretary Of Agriculture Method for the simultaneous and independent determination of moisture content and density of particulate materials from radio-frequency permittivity measurements
WO2002046357A1 (fr) 2000-10-26 2002-06-13 The Trustees Of Princeton University, Princeton University Procede et appareil de spectroscopie dielectrique de solutions biologiques
WO2005043142A2 (fr) * 2003-10-24 2005-05-12 Troxler Electronic Labs, Inc. Procedes et dispositifs de mesurage a micro-ondes de la densite d'un materiau de chaussee
EP1712900A1 (fr) 2005-04-15 2006-10-18 M. Alessandro Manneschi Dispositif d`analyse de la composition du contenu d`un recipient
WO2011064770A2 (fr) 2009-11-25 2011-06-03 S.A.E Afikim Milking Systems Agricultural Cooperative Ltd. Procédé et dispositif d'analyse spectroscopique diélectrique du lait

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
CEVOLI, C.; RAGNI, L.; GORI A.; BERARDINELLI A.; CABONI M. F.: "Quality parameter assessment of grated Parmigiano-Reggiano cheese by waveguide spectroscopy", JOURNAL OF FOOD ENGINEERING, vol. 113, no. 2, 2012, pages 201 - 209
CHIARA CEVOLI ET AL: "Quality parameter assessment of grated Parmigiano-Reggiano cheese by waveguide spectroscopy", JOURNAL OF FOOD ENGINEERING, vol. 113, no. 2, November 2012 (2012-11-01), pages 201 - 209, XP055113571, ISSN: 0260-8774, DOI: 10.1016/j.jfoodeng.2012.06.004 *
LUIGI RAGNI ET AL: "Non-destructive internal quality assessment of Hayward kiwifruit by waveguide spectroscopy", JOURNAL OF FOOD ENGINEERING, BARKING, ESSEX, GB, vol. 109, no. 1, 2 October 2011 (2011-10-02), pages 32 - 37, XP028109282, ISSN: 0260-8774, [retrieved on 20111012], DOI: 10.1016/J.JFOODENG.2011.10.002 *
RAGNI L ET AL: "A dielectric technique based on a one-chip network analyser to predict the quality indices of shell eggs", BIOSYSTEMS ENGINEERING, ACADEMIC PRESS, UK, vol. 100, no. 4, August 2008 (2008-08-01), pages 470 - 478, XP022938815, ISSN: 1537-5110, [retrieved on 20080616], DOI: 10.1016/J.BIOSYSTEMSENG.2008.04.015 *
RAGNI L ET AL: "A waveguide technique for non-destructive determination of egg quality parameters", JOURNAL OF FOOD ENGINEERING, BARKING, ESSEX, GB, vol. 100, no. 2, September 2010 (2010-09-01), pages 343 - 348, XP027071902, ISSN: 0260-8774, [retrieved on 20100523], DOI: 10.1016/J.JFOODENG.2010.04.020 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111954806A (zh) * 2018-04-17 2020-11-17 Ubt有限责任公司 用于材料的介电不连续性的微波测量的设备
US20210045652A1 (en) * 2018-04-17 2021-02-18 Ubt S.R.L. Device for microwave measurement of a dielectric discontinuity of a material
US11397159B1 (en) 2018-08-31 2022-07-26 Byte Nutrition Science Incorporated Systems, devices and methods for analyzing constituents of a material under test

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