Fabry perot structure coupled cavity sensing chip, preparation method thereof and detection system

Abstract

The application belongs to the technical field of optical sensors, and particularly relates to a Fabry-Perot structure coupled cavity sensing chip based on an optical vernier effect, a preparation method thereof and a testing system. The sensing chip comprises three plane mirrors and two square quartz microtubes; two plane mirrors and two square quartz microtubes form a sensing cavity in the middle; a middle plane mirror and a lower plane mirror form a reference cavity; the square quartz microtubes are hollow structures with two open ends, and can be combined with a micro-flow system; the application can amplify the sensitivity of a traditional Fabry-Perot resonant cavity sensing chip by 20-40 times, avoids the demand of a traditional Fabry-Perot resonant cavity sensor for a high quality factor, and can realize the detection of chemical biological reagents with ultra-low micro-concentration and ultra-small physical quantity; the Fabry-Perot structure coupled cavity is easy to manufacture, simple to operate, and low in overall design cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical sensors, and in particular relates to a Fabry-Perot structure coupled cavity sensor chip, a preparation method thereof, and a detection system. Background Art

[0002] Optical sensor technology generally offers advantages such as fast real-time detection, non-destructiveness, and strong resistance to electromagnetic interference. It is widely used in sensing physical parameters, chemical, and biological molecules. The Fabry-Perot coupled cavity, based on optical sensing technology, significantly amplifies the sensitivity of the coupled cavity due to the optical vernier effect. This extremely high sensitivity allows the coupled cavity to effectively resolve even weak signal changes, making it widely used in the detection of various chemical and biological molecules.

[0003] Typically, a Fabry-Pérot resonator (FP) consists of two highly parallel plane mirrors. Photons that meet the resonance conditions are confined within the cavity due to mirror reflection, forming a stable standing wave field. However, due to the inability to maintain high parallelism between the two plane mirrors during fabrication, additional optical losses are introduced, resulting in a sharp drop in the cavity's quality factor and reduced resolution. To overcome these issues, coupled cavities based on the Fabry-Pérot structure are widely used for weak signal detection due to their extremely high sensing sensitivity. A Fabry-Pérot coupled cavity consists of two cavities formed by three plane mirrors. Typically, one cavity serves as the sensing cavity and the other as the reference cavity, and the two cavities have similar lengths. Due to the slight difference in cavity length between the two Fabry-Pérot cavities, the final output spectrum is a superposition of the resonant modes of the two cavities, similar to the vernier effect. This ultimately forms an envelope in the transmission spectrum, which can be monitored for detection of the object under test. Furthermore, due to its extremely high sensitivity, the parallelism between the plane mirrors in the cavity is not strictly required.

[0004] Common Fabry-Perot coupled cavities are based on optical fiber structures, employing three reflective surfaces within the fiber to create an optical vernier effect. These fiber-based Fabry-Perot coupled cavities typically exhibit extremely high sensitivity and resolution, making them widely used for sensing various physical parameters, chemicals, and biomolecules. While fiber-based Fabry-Perot coupled cavities offer the advantage of ease of integration, the complex fabrication process and fragile fiber structure limit their practical application in optical sensor technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a Fabry-Perot structure coupled cavity sensor chip with extremely high sensitivity, low detection limit and label-free sensing, as well as a preparation method and a detection system thereof.

[0006] The Fabry-Perot structure coupled cavity sensor chip provided by the present invention is based on the optical vernier effect technology, and its structure is as follows Figure 1 As shown; it includes three plane reflectors and two square quartz microtubes, wherein the three plane reflectors are square and of the same size; the three plane reflectors are composed of a quartz substrate and a reflective film coated on the quartz substrate; the three plane reflectors are arranged in parallel in three layers: upper, middle and lower; the reflective films of the upper plane reflector and the middle plane reflector are opposite to each other; the two square quartz microtubes are of the same size and are arranged between the upper plane reflector and the middle plane reflector and are located at the edges of the two plane reflectors; the two plane reflectors are respectively connected to the two square quartz microtubes. The upper and lower surfaces of the quartz microtube are bonded together to form a sensing cavity between the two plane reflectors and the two square quartz microtubes; the reflective film side of the lower plane reflector is bonded to the quartz substrate of the middle plane reflector to form a reference cavity; the square quartz microtube is a hollow structure with openings at both ends, which can be combined with a microfluidic system; the square quartz microtube serves as a gasket between the two plane reflectors in the sensing cavity and provides a microfluidic channel for the transportation of the analyte to be measured; the quartz substrate of the middle plane reflector serves as a gasket between the two plane reflectors in the reference cavity.

[0007] In the present invention, there are three plane reflectors, and the reflectivity of each reflector ranges from 50% to 100%.

[0008] In the present invention, the surface reflective film of the plane reflector is a metal film with a specific reflectivity, such as a 30-50 nm thick gold film or silver film plated on a quartz substrate, so that the reflectivity range of the plane reflector is 50-100%, ensuring that any two reflectors can form a Fabry-Perot resonant cavity; or it is a dielectric film with multiple layers of high and low refractive index materials periodically cross-arranged, such as 11-31 layers of high and low refractive index materials deposited in sequence on a quartz substrate, so that the reflectivity range of the reflector is 50-100%, ensuring that any two reflectors can form a Fabry-Perot resonant cavity.

[0009] In the present invention, the square quartz microtubes and the plane reflectors, and the plane reflectors and the plane reflectors are bonded with each other using ultraviolet glue.

[0010] In the present invention, the plane reflector substrate is a light-transmitting quartz plate with a thickness of 200-1000 μm.

[0011] In the present invention, the height of the square quartz microtube does not exceed 1 mm, and can usually be 0.2-1 mm. The height of the square quartz microtube is close to the thickness of the quartz substrate of the intermediate plane reflector, for example, the difference does not exceed 0.02 mm.

[0012] The Fabry-Perot structure coupled cavity sensor chip described in the present invention effectively amplifies the sensitivity of the sensor chip by 20-40 times based on the optical vernier effect in the coupled cavity, and can be used to detect ultra-low concentration and trace amount of target detection solution.

[0013] The Fabry-Perot structure coupled cavity sensor chip described in the present invention can achieve real-time and rapid detection of the concentration of target detection objects (chemical molecules, biological molecules) through optical means based on the characteristic that the refractive index of the target detection object changes with the solution concentration.

[0014] The present invention also provides a method for preparing the above sensor chip, see Figure 2 As shown, the specific steps are:

[0015] (1) Select two square quartz microtubes, apply a layer of UV glue evenly on their lower surfaces, and lay them horizontally on the coated surface of the middle layer plane reflector, and glue them together with UV glue;

[0016] (2) Apply a layer of UV glue evenly on the upper surface of the square quartz microtube, place the coated surface of the top plane reflector on the upper surface of the square quartz microtube, and glue them together using UV glue;

[0017] (3) Apply a layer of UV glue evenly on the quartz base surface of the middle plane reflector, and bond the side of the bottom plane reflector coated with the reflective film to it.

[0018] The present invention also provides a detection system based on the above sensor chip, see Figure 4 As shown, it includes: a supercontinuum light source, a single-mode optical fiber, a beam collimator, a beam splitter, a focusing lens, a Fabry-Perot structure coupled cavity sensor chip based on the optical vernier effect, a focusing lens, a focusing lens or lens, a spectrum analyzer, and a computer, which are connected in sequence to form a sensing optical path; in addition, it also includes a focusing lens or lens and a CCD imaging device connected in sequence to the beam splitter to form an imaging optical path; wherein:

[0019] A supercontinuum light source is used to emit wide-band detection light; the wide-band detection light output by the light source is transmitted to a beam collimator by a single-mode optical fiber; the beam collimator is used to collimate the divergent light output by the single-mode optical fiber into parallel light; the beam splitter is used to transmit the image formed by the focusing objective lens to the CCD imaging device; the focusing objective lens is used to couple the collimated parallel light into a Fabry-Perot structure coupled cavity sensor chip, and is also used to collect the output light of the sensor chip and image the sensor chip; the Fabry-Perot structure coupled cavity sensor chip based on the optical vernier effect is a Fabry-Perot structure coupled cavity composed of three plane mirrors and two square quartz microtubes, wherein the square quartz microtube is a hollow structure with openings at both ends. One end is connected to a microfluidic system, which includes a Teflon tube and an injection pump, a syringe, a test tube, etc.; the other end is connected to the analyte to be tested through the Teflon tube; the spectral signal output by the focusing objective lens is fully collected by a large-core optical fiber bundle and transmitted to a spectrum analyzer; the spectrum analyzer receives the output light signal and converts it into an electrical signal and transmits it to a computer; the computer is used to display the output spectral signal collected by the spectrum analyzer and analyze and store the data; the CCD imaging device is used to image the Fabry-Perot structure coupled cavity sensor chip; the microfluidic system, including a syringe pump, a syringe and a Teflon tube, is used to extract the analyte to be tested into a square quartz microtube; the test tube is used to store the analyte to be tested.

[0020] The present invention also provides a detection method for the above-mentioned detection system, comprising: turning on a supercontinuum light source to emit detection light; coupling a focused light spot into a coupling cavity using a focusing objective lens; adjusting a square quartz microtube of the sensor chip to the focused light spot area using a CCD imaging system and a five-dimensional adjustment frame; extracting an analyte to be tested into the square quartz microtube using a microfluidic system (including a syringe pump, a syringe, a Teflon tube, a test tube, etc.), wherein the process comprises connecting the microfluidic system to one end of the square quartz microtube, and connecting the other end of the square quartz microtube to a test tube containing the analyte to be tested via the Teflon tube; and collecting signals using a spectrum analyzer and displaying and storing the data in real time using a computer.

[0021] The technical principle of the present invention is as follows: three plane mirrors and two square quartz microtubes are assembled into a Fabry-Perot structure coupled cavity with an optical vernier effect. The cavity lengths of the two cavities are similar, so the sensitivity of the sensor chip can be effectively amplified by 20-40 db. The amplification factor can be written as:

[0022] (1)

[0023] Where and are the free spectral ranges of the sensing cavity and reference cavity, respectively, and the size of the spectrum is related to the cavity length. According to formula (1), the closer the cavity lengths of the two cavities are, the larger the amplification factor is, but this also leads to a decrease in the resolution of the envelope. Therefore, the amplification factor of the coupled cavity is generally 1-2 orders of magnitude.

[0024] In this invention, because the two cavities (the reference cavity and the sensing cavity) have similar lengths, the output spectrum is a superposition of the resonant spectra of the two cavities, similar to the vernier effect, ultimately forming an envelope in the spectrum. This envelope has extremely high sensitivity, at least an order of magnitude higher than that of conventional Fabry-Perot resonant cavity sensors, thus enhancing the sensor chip's ability to detect weak signals.

[0025] The present invention has the following characteristics:

[0026] (1) The present invention is significantly different from the common fiber Fabry-Perot structure coupled cavity. In the present invention, three plane mirrors form a Fabry-Perot structure coupled cavity, wherein a square quartz microtube is integrated in the middle of the sensing cavity, and the middle of the reference cavity is the quartz substrate of the plane mirror. Since the lengths of the square quartz microtube and the quartz substrate of the plane mirror are similar, the sensitivity of the sensor chip can be highly amplified.

[0027] (2) The Fabry-Perot structure coupled cavity sensor chip provided by the present invention overcomes the complex preparation process and fragile structure of the traditional optical fiber Fabry-Perot structure coupled cavity, greatly improving the structural stability of the sensor chip and reducing its production cost;

[0028] (3) The square quartz microtube integrated in the present invention is itself a microfluidic channel, so there is no need to make an additional analyte transmission channel;

[0029] (4) The Fabry-Perot structure coupled cavity sensor chip provided by the present invention has extremely high sensitivity, which overcomes the requirement of traditional Fabry-Perot structure resonant cavity sensors for extremely high mirror parallelism;

[0030] (5) The biomolecule detection mechanism achieved by the present invention is that the specific binding between biomolecules leads to a large refractive index change. This process does not require labeling of biomolecules or chemical modification of the interior of the square quartz microtube, thus reducing the complexity of biomolecule detection.

[0031] (6) The Fabry-Perot structure coupled cavity sensor chip provided in the present invention can detect ultra-low concentration and trace volume biochemical molecules (proteins, DNA, chemical gases, bacteria and viruses) and weak physical quantity (temperature, pressure, refractive index) signals due to its extremely high sensitivity.

[0032] (7) The sensor chip provided by the present invention is simple to manufacture, easy to operate, and can be used repeatedly;

[0033] (8) The sensor chip testing method provided by the present invention is simple and has low requirements on the testing system, making it convenient for practical use. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the structure of the Fabry-Perot structure coupled cavity sensor chip of the present invention.

[0035] Figure 2 It is a flowchart of the preparation method of the Fabry-Perot structure coupled cavity sensor chip based on the present invention.

[0036] Figure 3 This is a diagram of the theoretically calculated transmission spectrum of the Fabry-Perot structure coupled cavity sensor chip of the present invention.

[0037] Figure 4 It is a diagram of a detection system based on the Fabry-Perot structure coupled cavity sensor chip of the present invention.

[0038] Figure 5 This is a diagram of the transmission spectrum of an experimental test of the Fabry-Perot structure coupled cavity sensor chip of the present invention.

[0039] Figure 6 It is a diagram showing the sensitivity test results of the Fabry-Perot structure coupled cavity sensor chip according to the present invention.

[0040] The numbers in the figure are: 1 is the quartz substrate of the upper and lower reflectors; 2 is the quartz substrate of the middle reflector; 3 is the reflective film; 4 is the square quartz microtube; 5 is the supercontinuum light source; 6 is the beam collimator; 7 is the beam splitter; 8 is the focusing objective lens; 9 is the Fabry-Perot structure coupled cavity sensor chip; 10 is the focusing objective lens; 11 is the focusing objective lens or lens; 12 is the spectrum analyzer; 13 is the computer; 14 is the focusing objective lens or lens; 15 is the CCD imaging device; 16 is the microfluidic system, 17 is the sensing optical path; 18 is the imaging optical path. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the present invention is not limited to these examples. Example 1

[0042] In this embodiment, the Fabry-Perot structure coupled cavity sensor chip based on the optical vernier effect (see Figure 1), specifically comprising: three planar mirrors plated with specific reflective film and a Fabry-Perot structure coupling cavity composed of two square quartz microtubes; wherein the reflectivity of the planar mirror ranges from 50% to 100%, and the thickness of the quartz substrate is 200-1000 μm; the two square quartz microtubes have a height not exceeding 1 mm, and the height of the square quartz microtubes is close to the thickness of the planar mirror substrate quartz sheet; the square quartz microtubes have openings at both ends and can be combined with a microfluidic system; the square quartz microtubes and the mirror plated with reflective film are adhered by ultraviolet glue; the sensing cavity in the coupling cavity is the lower surface of the square quartz microtube and the surface of the middle planar mirror plated with reflective film, and the upper surface of the square quartz microtube and the surface of the upper planar mirror plated with reflective film are adhered; the reference cavity in the coupling cavity is the surface of the middle planar mirror without reflective film and the surface of the bottom planar mirror plated with film.

[0043] In the device, the preparation method of the Fabry-Perot structure coupling cavity sensing chip is as shown in Figure 2 , which comprises:

[0044] (1) Select two square quartz microtubes, uniformly apply a layer of ultraviolet glue on the lower surface of each, and horizontally lay them on the film-coated surface of the middle layer planar mirror and adhere them with ultraviolet glue, as shown in Figure 2 (b);

[0045] (2) Uniformly apply a layer of ultraviolet glue on the upper surface of the square quartz microtubes, lay the film-coated surface of the top layer planar mirror on the upper surface of the square quartz microtubes and adhere them with ultraviolet glue, as shown in Figure 2 (c);

[0046] (3) Uniformly apply a layer of ultraviolet glue on the quartz substrate surface of the middle layer planar mirror, and adhere the surface of the bottom layer planar mirror plated with reflective film, as shown in Figure 2 (d).

[0047] In the device, when light is incident on the above-mentioned sensing chip, part of the light will pass through the mirror surface into the Fabry-Perot structure coupling cavity, wherein the light satisfying the sensing cavity and the reference cavity will generate stable resonance in the two cavities respectively, and the final output spectrum is the superposition of the transmission spectra of the two resonance cavities; due to the slight difference in the cavity length of the two cavities, when the two transmission spectra are superimposed, an envelope is formed similar to the vernier effect; when the concentration of the liquid in the sensing cavity changes, the corresponding refractive index also changes, and the resonance mode of the sensing cavity moves, and in the transmission spectrum, the envelope moves, so by monitoring the size of the envelope peak value, the sensing of specific concentration analytes (chemical molecules, biological molecules) can be realized. Example 2

[0048] In this embodiment, based on the parameters of Example 1, the theoretical analysis of the Fabry-Perot structure coupled cavity sensing chip is carried out. Based on the double Fabry-Perot resonant cavity coupling mode, the normalized amplitude transmission coefficient of the final Fabry-Perot structure coupled cavity can be derived as:

[0049] (2)

[0050] Wherein, is the amplitude reflection coefficient of the reference cavity, which can be written as:

[0051] (3)

[0052] Wherein, is the amplitude transmission coefficient of the reference cavity, which can be written as:

[0053] (4)

[0054] In the above formula, and are the reflectivity of the three plane mirrors respectively; and are the transmissivity of the three plane mirrors respectively; and are the height of the square quartz microtube and the thickness of the middle plane mirror quartz substrate respectively; and are the loss factors introduced in the sensing cavity and the reference cavity due to absorption, scattering and the like; and are the phase difference introduced after the light is reflected back and forth in the sensing cavity and the reference cavity once, which can be written as:

[0055] (5)

[0056] Wherein, υ is the frequency of the incident light, c is the speed of light in vacuum, and and are the effective refractive index of the medium in the sensing cavity and the reference cavity respectively.

[0057] By combining formulas (1)-(4), the output transmission spectrum of the Fabry-Perot structure coupled cavity can be obtained, as shown in Figure 3 With the change of the concentration of the analyte in the square quartz microtube, the envelope in the corresponding transmission spectrum moves a large wavelength. Example 3

[0058] In this embodiment, based on the parameters of Example 1, the transmission spectrum of the sensing chip and the bulk refractive index sensitivity are tested, and the specific process is as follows: the prepared Fabry-Perot structure coupled cavity sensing chip is combined with microfluidic technology, that is, one end of the square quartz microtube is combined with a syringe and a syringe pump through a Teflon tube to realize the extraction of the liquid to be tested; the other end of the square quartz microtube is combined with the liquid to be tested through a Teflon tube.

[0059] In the device, the test system is as shown in Figure 4As shown. Turn on the supercontinuum light source and emit detection light; after the light beam passes through the fiber collimator, it is collimated into parallel light and passes through the beam splitter and focusing objective lens in sequence. The parallel light beam is focused into a small spot and effectively coupled to the square quartz microtube area of ​​the Fabry-Perot structure coupling cavity by combining with the CCD imaging device; the transmission spectrum of the Fabry-Perot structure coupling cavity is collected by the focusing objective lens and further collimated into parallel light and transmitted to the remote lens or focusing objective lens. Finally, the transmission spectrum is analyzed by the spectrum analyzer and the spectrum is displayed on the computer. The transmission spectrum of the Fabry-Perot structure coupling cavity tested in the experiment is shown as follows: Figure 5 shown.

[0060] In this device, based on the above test method, dimethylsulfoxide (DMSO) solutions with concentrations of 0-5% were passed into a square quartz microtube, and the movement of the envelope was observed in real time by a computer. Figure 5 As shown. With the increase of the concentration of dimethyl sulfoxide solution, the corresponding envelope peak red-shifts. By extracting and fitting the envelope peak, the sensitivity of the Fabry-Perot structure coupled cavity is obtained to be 3835 nm / RIU, as shown in Figure 6 As shown, the sensitivity amplification factor is 20 times that of the conventional Fabry-Perot cavity.

Claims

1. A Fabry-Perot structure coupled cavity sensor chip based on optical vernier effect, characterized in that: The invention comprises three plane reflectors and two square quartz microtubes; wherein the three plane reflectors are square and of the same size; the three plane reflectors are composed of a quartz substrate and a reflective film coated on the quartz substrate; the three plane reflectors are arranged in parallel in three layers: upper, middle and lower; the reflective films of the upper plane reflector and the middle plane reflector are aligned; the two square quartz microtubes are of the same size and are arranged between the upper plane reflector and the middle plane reflector and at the edges of the two plane reflectors; the two plane reflectors are respectively connected to the two square quartz microtubes. The upper and lower surfaces of the tube are bonded together to form a sensing cavity between the two plane reflectors and the two square quartz microtubes; the reflective film side of the lower plane reflector is bonded to the quartz substrate of the middle plane reflector to form a reference cavity; the square quartz microtube is a hollow structure with openings at both ends, which can be combined with a microfluidic system; the square quartz microtube serves as a gasket between the two plane reflectors in the sensing cavity and provides a microfluidic channel for the transportation of the analyte to be measured; the quartz substrate of the middle plane reflector serves as a gasket between the two plane reflectors in the reference cavity.

2. The Fabry-Perot structure coupled cavity sensor chip according to claim 1, characterized in that: The reflectivity of the plane mirror ranges from 50% to 100%.

3. The Fabry-Perot structure coupled cavity sensor chip according to claim 1, characterized in that: The surface reflective film of the plane reflector is a metal film with a specific reflectivity, or a dielectric film with multiple layers of high and low refractive index materials periodically cross-arranged, so that the reflectivity of the reflector ranges from 50-100%, ensuring that any two reflectors form a Fabry-Perot resonant cavity.

4. The Fabry-Perot structure coupled cavity sensor chip according to claim 1, characterized in that: The square quartz microtube and the plane reflector, and the plane reflectors and the plane reflectors are bonded together by ultraviolet glue.

5. The Fabry-Perot structure coupled cavity sensor chip according to claim 1, characterized in that: The plane reflector substrate is a light-transmitting quartz plate with a thickness of 200-1000 μm.

6. The Fabry-Perot structure coupled cavity sensor chip according to claim 1, characterized in that: The height of the square quartz microtube does not exceed 1 mm, and the height of the square quartz microtube is close to the thickness of the quartz substrate of the intermediate plane reflector.

7. A method for preparing a Fabry-Perot structure coupled cavity sensor chip according to any one of claims 1 to 6, characterized in that: The specific steps are: (1) Select two square quartz microtubes, apply a layer of UV glue evenly on their lower surfaces, and lay them horizontally on the coated surface of the middle layer plane reflector, and glue them together with UV glue; (2) Apply a layer of UV glue evenly on the upper surface of the square quartz microtube, place the coated surface of the top plane reflector on the upper surface of the square quartz microtube, and glue them together using UV glue; (3) Apply a layer of UV glue evenly on the quartz base surface of the middle plane reflector, and bond the side of the bottom plane reflector coated with the reflective film to it.

8. A detection system based on the Fabry-Perot structure coupled cavity sensor chip according to any one of claims 1 to 6, characterized in that: include: A supercontinuum light source, a single-mode optical fiber, a beam collimator, a beam splitter, a focusing objective lens, a Fabry-Perot structure coupled cavity sensor chip based on the optical vernier effect, a focusing objective lens, a focusing objective lens or lens, a spectrum analyzer, and a computer are connected in sequence to form a sensing optical path; in addition, a focusing objective lens or lens and a CCD imaging device connected in sequence to the beam splitter are also included to form an imaging optical path; wherein: The supercontinuum light source is used to emit wide-band detection light; The single-mode optical fiber transmits the output wide-band detection light of the light source to the beam collimator; The beam collimator is used to collimate the divergent light output by the single-mode optical fiber into parallel light; The beam splitter is used to transmit the image formed by the focusing objective lens to the CCD imaging device; The focusing objective lens is used to couple the collimated parallel light into the Fabry-Perot structure coupled cavity sensor chip, and is also used to collect the output light of the sensor chip and to image the sensor chip; In the Fabry-Perot structure coupled cavity sensor chip, both ends of the square quartz microtube are open, one end is connected to the microfluidic system, and the other end is connected to the analyte to be measured through a Teflon tube; the spectral signal output by the focusing objective lens is fully collected by the large-core optical fiber bundle and transmitted to the spectrum analyzer; The optical spectrum analyzer receives the output optical signal and converts it into an electrical signal and transmits it to the computer; The computer is used to display the outgoing spectrum signal collected by the spectrum analyzer and analyze and store the data; The CCD imaging device is used to image the Fabry-Perot structure coupled cavity sensor chip; The microfluidic system includes a syringe pump, a syringe, and a Teflon tube, which are used to extract the analyte to be tested into a square quartz microtube.

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