JP2007178414A - Method and system for testing sugar content - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To noncontactly or nondestructively discriminate a sugar content in a measured object. <P>SOLUTION: A method and system for testing sugar contents irradiates the measured object with a generated electromagnetic wave to obtain a transmission or reflection intensity thereof, using an electromagnetic wave generation source having 10GHz-10THz of oscillation frequency constituted of a terahertz generator, and using a suitable frequency of oscillation element, and obtains thereby the sugar content in the measured object and a distribution situation thereof. A distribution of the sugar content in the measured object is imaged by sweeping either of the measured object or the test system, by measurement of narrowing thinly a measuring beam. Further, the sugar content is highly sensitively detected nondestructively and noncontactly as to the sample in a liquid cell, even on the measurement of the sugar content in the sampled liquid sample. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention uses fruits, living organisms, or liquid samples as objects to be measured, irradiates the objects to be measured with electromagnetic waves, and measures their transmission intensity or reflection intensity, thereby containing them in a non-destructive and non-contact manner. It can be an effective evaluation method in fields such as agricultural product management, medical practice, and food management.

  Until now, the sugar content of fruits has been determined by measuring the refractive index with light using the extracted fruit juice. Due to the growing need for non-destructive and non-contact measurement methods for fruits, sugar content detection using infrared light has been used as a test, but infrared light has a shallow penetration depth into liquids. There was a problem that the measurement results varied greatly depending on the surface condition of the object to be measured. For this reason, since the sugar content measurement by the destructive inspection of the extracted sample is employ | adopted, the difference etc. between a goods and a measurement sample became a problem.

  In addition, for measuring blood glucose levels in human blood, the enzyme electrode method and the enzyme colorimetric method have been used in the past, and the measurement using the extracted blood reaction is often performed. I had to stab and sample the necessary amount of blood, and there was a physical or mental burden.

  The present invention overcomes the problems associated with liquid sample extraction in conventional sugar content measurement using visible light and infrared rays, and uses electromagnetic waves in the range of 10 GHz to 10 THz, so that non-destructive and non-contact measurement objects can be obtained. This realizes high-accuracy sugar content detection.

  In order to solve the above problem, in the present invention, an electromagnetic wave generation source having an oscillation frequency of 10 GHz to 10 THz constituted by a terahertz generator is used, an oscillation source having a suitable frequency is used, and the generated electromagnetic wave is applied to an object to be measured. By irradiating and obtaining the transmission or reflection intensity, it is possible to obtain the sugar content in the object to be measured and its distribution information. In addition, for liquid samples, by measuring the scattering or reflection component of electromagnetic waves by an aqueous sugar solution aggregated around the film by measuring through a film such as polyvinylidene chloride wrap, polyvinyl chloride wrap, or polyethylene wrap, Realizes highly sensitive detection of sugar content.

  The sugar content inspection method and the inspection system of the present invention use an electromagnetic wave generation source in the range of 10 GHz to 10 THz constituted by a terahertz generator, select a wavelength suitable for the medium and the measurement object, and The sugar content can be identified in a non-contact or non-destructive manner. Further, by measuring either the measurement object or the inspection system optical unit by measuring the measurement beam narrowly, the sugar content distribution in the measurement object can be imaged.

  In addition, regarding the measurement of sugar content in a sampled liquid sample, it is possible to detect the sugar content with high sensitivity in a non-destructive / contacted manner with respect to the sample. For this reason, the sugar content test method and test system according to the present invention are expected to be effective in fields such as agricultural product management, medical practice, and food management.

A resonator structure of a diode oscillation element used in the sugar content inspection method and inspection system according to the present invention is shown in FIG. The resonator is formed in a metallic resonator basic structure 1 by a stem 2, a sliding short 3, a bias pin 4, a rectangular waveguide 5, a horn antenna 6, a quartz standoff 7, a diode element 8, and a gold ribbon 9. The bottom surface side of the quartz standoff 7 and the diode element 8 are pressure-bonded onto the stem 2, and the respective upper surface sides are connected by a gold ribbon 9. The bias pin 4 has a λ / 4 choke structure, is placed in contact with the standoff 7, and supplies a necessary DC bias to the diode element 8. A resonator is formed in the vicinity of the contact point between the bias pin 4 and the quartz standoff 7 and the space length surrounded by the sliding short 3, and the electromagnetic wave stored in the resonator is output from the horn antenna 6 through the rectangular waveguide 5. As shown in FIG. 2, the element structure of the tannet diode is an n ⁺ GaAs substrate crystal 81, a low-concentration electron density GaAsn ⁻ layer 82, a high-concentration electron density GaAsn ⁺ layer 83, and a high-concentration hole density. The GaAsp ⁺ layer 84 is formed by epitaxial growth. After being epitaxially grown by processing thin substrate 81 to about 10 to 50 [mu] m, the p ⁺ layer 84 side are bonded in contact with the stem 2, it is installed in the resonator structure.

  An electromagnetic wave generator that continuously oscillates the fundamental wave at room temperature can be produced in the range of 10 GHz to 1 THz by the tannet diode oscillation element. For example, in a waveguide resonator structure based on WR12 (3.099 mm × 1.549 mm), the oscillation frequency range is 60 to 90 GHz. By selecting a suitable waveguide size and resonator structure, and also a suitable diode structure, an arbitrary tannet diode that oscillates in the range of 10 GHz to 1 THz was fabricated and realized. For example, literature (J. Nishizawa, P. Plotka, H. Makave, T. Kurabayashi, IEEE Microwave and Wireless Components, 15, 597, 2005).

  Gunn diode, impatt diode, tannet diode, quantum cascade laser, p-type germanium laser, resonant tunneling diode, etc., electron tube such as packed word oscillator, high-frequency transistor oscillator, free electron laser, terahertz time domain A terahertz generation method by spectroscopy, a terahertz parametric oscillator, a terahertz difference frequency generator using a semiconductor crystal such as GaP, and the like can be used, and an arbitrary electromagnetic wave wavelength can be selected in the range of 10 GHz to 10 THz.

  In particular, when the GaP terahertz wave generation method is used, generation of a terahertz electromagnetic wave having a variable wavelength and a high output is realized in an unparalleled range of 0.15 to 7 THz (for example, T. Tanabe, K Suto, J. Nishizawa, T. Kimura, K. Saito, Journal of Applied Physics 93, 4610, 2003) Although it is a single light source, it has a feature that an arbitrary frequency of a terahertz electromagnetic wave can be selected in a wide range. In the GaP terahertz wave generation method, a YAG laser having a wavelength of 1.064 μm is used as the first pump light, and an optical parametric oscillator (OPO) equipped with an injection seeding device is used as the second pump light source, that is, the wavelength tunable light source. As a second method, a Cr: FORSTERITE (Cr-added olivine) laser can be used as pump light. Since this laser uses the Cr level, the line width is extremely narrow compared to OPO without injection seeding. The Cr: FORSTERITE laser is excited using a YAG laser with a wavelength of 1.064 μm. The wavelength tunable range of the Cr: FORSTERITE laser is the range from 1.15 μm to 1.35 μm, two Cr: FORSTERITE lasers are used as pump light sources, one is a fixed wavelength, and the other is used as a wavelength tunable pump light source, Difference frequency can be generated without injection seeding.

  FIG. 3 is a diagram for explaining a transmission intensity measuring method and system using a liquid cell using a tannet diode oscillation element. The electromagnetic wave having a predetermined frequency generated from the oscillation element 10 is converted into a parallel beam by the lens 11 installed in the vicinity of the exit of the oscillation element 10, passes through the liquid filling portion 13 of the liquid cell 12, and is collected by the lens 11. The intensity is detected by the detector 19. The liquid cell was produced using Teflon (PTFE) as a material. The object to be measured 14 is a liquid sample, which is filled into the liquid cell 12 through the liquid introduction tube 15 and the liquid sample introduction port 16 and discharged through the liquid discharge port 17. In actual measurement, an evacuation device was connected after the liquid discharge port 17 to discharge the liquid in the liquid filling unit 13 and sequentially replace and introduce the liquid sample to be measured. 18 is a visualization of the transmission direction of electromagnetic waves. The pulse generator 20 is used to turn on and off the oscillation element 10 and uses 1 to 4 kHz and a duty of 0.5 as typical values. The signal detected by the detector 19 was output to the computer 22 via the lock-in amplifier 21.

  FIG. 4 shows an example in which a tannet diode that oscillates at 200 GHz is used as the oscillation element, and the electromagnetic wave transmittance for each concentration of the glucose aqueous solution is measured. The thickness of the liquid filled in the liquid cell was 300 μm. From this result, it was found that the electromagnetic wave transmittance tends to increase linearly with the increase in the glucose concentration in the aqueous solution. This electromagnetic wave transmittance is the electromagnetic wave transmission intensity when the sugar concentration is 0. Further, in this measurement, it was also possible to identify the amount of glucose contained in the case of using human blood and serum and infusion liquid transfusion.

  As described above, in the permeation characteristic measurement using the liquid cell according to the present invention, the sugar content at a concentration of about 0.1% can be accurately measured. Furthermore, blood sugar levels in blood and serum can be measured with high accuracy.

  FIG. 5 is a diagram for explaining a measurement method and a measurement system related to transmission imaging of a measurement object 14 containing sugar. The beam system is narrowed down near the object to be measured 14, and a conical aperture 24 is attached near the focal point to further reduce the beam diameter, thereby realizing high resolution during imaging. The other apparatus configuration is substantially the same as that shown in FIG. 3, but this apparatus includes a drive mechanism 23 for the object 14 to be measured, and measures and maps the electromagnetic wave transmission intensity at each measurement point of the sample. Makes it possible to obtain a transmission image.

  FIG. 6 (upper) shows a sample shape obtained by laminating filter paper 31 soaked in a glucose aqueous solution of each concentration. The concentration of the aqueous glucose solution soaked in each filter paper is A: 0 mg / dl, B: 500 mg / dl, C: 1000 mg / dl, D: 2000 mg / dl, E: 3000 mg / dl, F4500 mg / dl. The laminate sample 30 is effective as a sample forming method capable of stably measuring the sugar content by preventing the evaporation of moisture and maintaining the concentration of the aqueous glucose solution in the filter paper. FIG. 6 (bottom) is a schematic diagram for explaining a transmission imaging image of the laminate sample 30 measured using an electromagnetic wave of 200 GHz. The transmission imaging image 32 includes a filter paper transmission image 33, and it is shown that the electromagnetic wave transmission intensity at 200 GHz increases as the glucose concentration increases, and a clear difference is seen in image density. FIG. 7 is a plot of transmission intensity data corresponding to each shade. In the transmission intensity obtained by imaging, it was found that the electromagnetic wave transmittance tended to increase linearly corresponding to the increase in the glucose concentration of the aqueous solution, as in the measurement using the liquid cell. The electromagnetic wave transmittance is set to 1 in pure water when no sugar is contained.

  FIG. 8 is a diagram for explaining a method and system for measuring the reflection intensity of an object to be measured using a diode oscillation element. The electromagnetic wave having a predetermined frequency generated from the oscillation element 10 is converted into a parallel beam by the lens 11 installed near the exit of the oscillation element 10, passes through the beam splitter 25, and then is transmitted by the lens 11 installed near the object to be measured 14. While narrowing down the beam diameter, the aperture 24 further narrows the beam diameter and irradiates the object 14 to be measured. The object to be measured 14 is covered with a film 26. When the object to be measured is a fruit, the film 26 corresponds to the skin of the fruit, and when the object to be measured is a human body, the film 26 corresponds to the skin, and the object 14 to be measured is blood. It corresponds to. The DUT 14 is installed near the exit of the aperture 24 via the stage 27. The irradiated electromagnetic wave passes through the film 26, is reflected or scattered inside the object to be measured 14, passes through the aperture 24 from the object to be measured side, is converted into a parallel beam by the lens 11, and is reflected by the beam splitter 25. Then, the light is guided to the detector 19 via the lens 11. Since the electromagnetic wave component returning to the electromagnetic wave irradiation side is measured in this way, it is referred to as reflection intensity measurement for the sake of convenience, but includes scattering / absorption due to the internal components of the measurement object 14. Needless to say. In addition, the object to be measured 14 (liquid component) in the test tube 29 as the object to be measured is passed through a film 28 (either a polyvinylidene chloride wrap, a polyvinyl chloride wrap, or a polyethylene wrap). By measuring the reflection intensity from the liquid, a phenomenon in which high sensitivity is realized has been confirmed. The measurement of glucose concentration in pure water and serum is most sensitive when polyethylene wrap is used, which seems to reflect the phenomenon that glucose is distributed at a high concentration near the film. Specifically, it may reflect the solute adsorption phenomenon near the film, and among the polyvinylidene chloride wrap, polyvinyl chloride wrap, and polyethylene wrap, polyethylene wrap has the strongest adsorption characteristics. thinking.

  FIG. 9 shows a comparative measurement result of the sugar content and the reflection intensity of the cherries using the system of FIG. Cherry A is Napoleon, B is Nishiki Sato, and C is Yamagata Bijin. In the reflection intensity measurement, various cherries were installed at the position of the DUT 14 shown in FIG. 8 to measure the reflection intensity. The sugar content (Brix%) of various cherries was measured using a conventional saccharimeter after partially grinding the sample after measuring the reflection intensity and extracting the juice. The conventional method is a so-called destructive inspection. Although the appearance such as the skin color of the various cherries is remarkably different, the reflection intensity measurement using a 200 GHz electromagnetic wave revealed that the same characteristic curve was exhibited regardless of the type of cherries in a non-contact and non-destructive manner. This is an example showing that non-contact / non-destructive inspection using terahertz electromagnetic waves is an effective means to replace conventional destructive testing by juice extraction.

  FIG. 10 is an explanatory diagram of a reflection intensity measurement probe in which the oscillation source 10, the detector 19, and the optical system are combined. An electromagnetic wave having a predetermined frequency generated from the oscillation element 10 is radiated to free space through a horn antenna attached to the element, is converted into a parallel beam by the lens 11 installed near the exit of the oscillation element 10, passes through the beam splitter 25, The light is emitted from the probe end portion 35 having an aperture function to the outside of the probe. By bringing the object to be measured into contact with the outside of the probe, the reflected light from the object to be measured is guided again into the probe, and after passing through the lens 11, the optical path is switched by reflection by the beam splitter 25, and the detector 19 is connected via the mirror 34. And the reflection intensity is measured. As a feature of this system, since the entire optical system is integrated, measurement can be performed by moving the probe and bringing the probe tip into contact with the object to be measured. It has the feature that it is easy to apply to. It can also be applied to the measurement of the reflection intensity of a specific part such as the upper arm or the lower limb of the human body.

  As described above, in the sugar content inspection method and inspection system of the present application, an electromagnetic wave generation source in the range of 10 GHz to 10 THz is used, an oscillation source having a frequency suitable for the medium is selected, and the sugar content in the object to be measured is determined in a non-contact or non-contact manner. It becomes possible to identify by destruction, and the sugar content distribution in the measurement object can be imaged by sweeping either the measurement object or the inspection system of the present invention. Furthermore, regarding the sugar content measurement in the sampled liquid sample, it is possible to detect the sugar content with high sensitivity by non-destructive and non-contacting the sample in the liquid cell. Therefore, the sugar content test method and test system according to the present invention can be an effective test method and test system in fields such as agricultural product management, medical practice, and food management.

  It is the schematic of the resonator structure of a diode oscillation element.   It is the crystal structure schematic of a tannet diode.   It is explanatory drawing which shows the permeation | transmission intensity | strength measuring method and system by a liquid cell using a diode oscillation element.   This is a measurement example of electromagnetic wave transmittance for each concentration of an aqueous glucose solution using a tannet diode that oscillates at 200 GHz as an oscillation element.   It is explanatory drawing which shows the measuring method and measuring system regarding the transmission imaging of the to-be-measured object containing sugar.   (Upper) is an explanatory diagram of a sample preparation procedure when filter paper soaked in glucose aqueous solutions having different concentrations is used as an object to be measured. (Lower) is a schematic diagram for explaining a transmission imaging image of a sample (upper) measured using an electromagnetic wave of 200 GHz.   It is an example of a measurement which shows the relationship between the electromagnetic wave transmittance obtained from a transmission imaging image, and sugar concentration.   It is explanatory drawing which shows the reflection intensity measuring method and system of a to-be-measured object using a diode oscillation element.   9 is a comparative measurement example of sugar content and reflection intensity of cherries using the system of FIG.   It is explanatory drawing of the probe for a reflection intensity measurement.

Explanation of symbols

1 ... resonator base structure 2 ... stem 3 ... Sliding Short 4 ... bias pin 5 ... rectangular waveguide 6 ... horn antenna 7 ... quartz standoff 8 ... diode element 9 ... gold ribbon 81 ^... n + GaAs substrate crystal 82 ... GaAs n ^- Layer 83 ... GaAsn ⁺ layer 84 ... GaAsp ⁺ layer 10 ... Oscillating element 11 ... Lens 12 ... Liquid cell 13 ... Liquid filling portion 14 ... Measurement object 15 ... Liquid introduction tube 16 ... Liquid sample introduction port 17 ... Liquid discharge port 18 ... Electromagnetic transmission direction 19 ... Detector 20 ... Pulse generator 21 ... Lock-in amplifier 22 ... Computer 23 ... Drive mechanism 24 ... Aperture 25 ... Beam splitter 26 ... Film 27 ... Stage 28 ... Film (polyvinylidene chloride wrap, polychlorinated) Vinyl wrap or polyethylene wrap)
29 ... Test tube 30 ... Laminated sample 31 ... Filter paper 32 ... Transmission imaging image 33 ... Filter paper transmission image

Claims (6)

  An inspection system comprising an electromagnetic wave generation source in the range of 10 GHz to 10 THz constituted by a terahertz generator and comprising at least the electromagnetic wave generation means, the light collection means, and the detection means, and irradiates the object to be measured with the electromagnetic waves A sugar content test method and a test system capable of detecting the sugar content and blood glucose level contained in the object to be measured by measuring the transmission intensity or reflection intensity at the time of measurement.   In the inspection system, a probe structure in which the generating means, the light collecting means, and the detecting means are integrated, and the sugar content and blood sugar level contained in the measurement object are detected by bringing the probe close to or in contact with the measurement object. The sugar content test method and test system according to claim 1, which makes it possible.   In the inspection system, the surface of the object to be measured is covered with a film, and the transmission or reflection intensity from the vicinity of the film surface is measured, so that the sugar content, blood glucose level and distribution state thereof are measured with high sensitivity. The sugar content test method and test system according to claim 1, wherein the sugar content test method and test system can be performed.   The sugar content test method and test system according to claim 3, wherein any one of a polyvinylidene chloride film, a polyvinyl chloride film, and a polyethylene film is used as the film.   2. The inspection system according to claim 1, wherein a liquid component to be measured is impregnated into filter paper or nitrocellulose paper, and a sample subjected to lamination processing in a dry or wet state is used as the measurement object. 2. The sugar content test method and test system according to 1.   The terahertz generator includes an element such as a tannet diode, a Gunn diode, an input diode, a quantum cascade laser, a p-type germanium laser, a resonant tunneling diode, an electron tube such as a backward oscillator, an oscillator using a high-frequency transistor, and a free electron laser 6. The sugar content test according to claim 1, wherein the terahertz generation method is based on terahertz time-domain spectroscopy, a terahertz parametric oscillator, or a terahertz difference frequency generator using a semiconductor crystal such as GaP. Method and inspection system.

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