CN101750462B - Solid thermal conductivity detector for cylindrical thermal sensitive region - Google Patents

Abstract

The invention relates to a solid-state thermal conductivity detector, which is a gas thermal conductivity sensor and is used for gas chromatography and gas composition change detection. The invention comprises a columnar thermosensitive element and a flow cell body. The columnar thermosensitive element is composed of a columnar support with thermosensitive electrodes fixed on the surface. The lead-out electrodes at the same end are connected; the inner cavity of the flow cell body is cylindrical, and the space formed by the cylindrical thermosensitive element and the inner cavity of the flow cell is used as a detection cell; the cylindrical thermal element is embedded in the flow cell body, and the columnar support The axis of the flow cell is coaxial with the axis of the detection cell, and the two ends of the flow cell body are respectively provided with a gas inlet and a gas outlet, and the gas inlet is arranged on the axis of the detection cell; the lead-out electrode is electrically connected to the external circuit through the lead-out wire. The temperature-resistant stability of the detector of the invention varies with the heat-sensitive materials used, and the metal wire can reach 400°C, which not only improves the temperature resistance of the device, but also simplifies the manufacturing process and requirements, and broadens the application field.

Description

A Solid-state Thermal Conductivity Detector with Cylindrical Thermal Sensitive Area

technical field

The invention relates to a solid-state thermal conductivity detector, which is a gas thermal conductivity sensor, which is used for gas chromatography and gas composition change detection, and is widely used in industrial online instruments and laboratory analysis instruments.

Background technique

The miniaturization of analytical instruments is the mainstream of the development of analytical instruments in the 21st century. Miniaturization not only reduces the volume and weight of the instrument, but also reduces the power consumption and material consumption of the instrument. The key to the miniaturization of the instrument is the miniaturization of the detector or sensor, which reduces the volume and power consumption of the detection cell by more than 90%, and then can use a smaller separation column and power supply, which greatly reduces the energy consumption and carrier gas consumption. reduce.

Solid State Thermal Conductivity Detector (SSD for short) is essentially a gas thermal conductivity sensor, mainly used in gas chromatography detectors, detectors in industrial online instruments, and sensors that need to measure changes in gas composition .

左右的镍层，用光刻工艺刻蚀出梳状或网状镍电极。为提高热敏电极基底区的绝热性能并减小热容量，利用单晶硅的可定向腐蚀特性，将热敏电极区背面的单晶硅腐蚀掉，形成以SiO₂薄膜和Pyrex玻璃支撑的热悬浮区，使检测器有极高的检测灵敏度。检测器的腔体上盖也是由单晶硅制成，因为它有良好的导热性能。如美国Agilent公司生产的SSD和德国的Freiburg大学的IMTEK研究所研制的SSD都是用上述技术实现的。SSDs can be implemented with two technologies. One is to use the surface of single crystal silicon to be oxidized into a _SiO2 film and further sputter a layer of Pyrex glass on it, and then sputter

For the left and right nickel layers, comb-shaped or mesh-shaped nickel electrodes are etched by photolithography. In order to improve the heat insulation performance of the base area of the thermally sensitive electrode and reduce the heat capacity, the single crystal silicon on the back of the thermally sensitive electrode area is etched away by utilizing the directional etching characteristics of single crystal silicon, forming a thermal suspension supported by _SiO2 film and Pyrex glass. area, so that the detector has extremely high detection sensitivity. The detector cavity cover is also made of single crystal silicon because of its good thermal conductivity. For example, the SSD produced by Agilent Corporation of the United States and the SSD developed by the IMTEK Institute of Freiburg University in Germany are all realized by the above-mentioned technology.

However, the thermal expansion coefficients of SiO ₂ film, Pyrex glass and nickel metal electrodes are very different. When the detector temperature drops from 150°C to room temperature, not only cracks will occur in the Pyrex glass layer, but also the nickel electrode will contact with the Pyrex glass layer. Peel off and damage the detector. Therefore the maximum operating temperature of this detector is 90°C. It can only be used to measure groups with lower boiling points, and the application objects are limited.

Another technology uses a glass-ceramic-ceramic substrate, sputtering or chemically depositing a nickel or platinum metal film on it, and then making a thermosensitive electrode by photolithography or mechanical engraving, and then making it with a material with good thermal conductivity The cavity of the flow cell uses the heat-sensitive substrate as the side wall of the cavity to form an SSD. Such as the technology described in Chinese invention patent ZL200410046348.0.

There are 2 corners in the SSD flow cell using the glass-ceramic-ceramic substrate, which will cause disturbance when the air flow passes through, which will increase the noise and band mixing effect.

The metal thin film of the thermosensitive electrode of the existing SSD is deposited by sputtering or chemical deposition, the thickness is only 0.1-1 μm, and the crystal structure of the metal has many defects, so the long-term stability is not good, and the temperature of the heating wire generally cannot over 200°C to prevent damage.

The thermosensitive element in the traditional thermal conductivity detector is wound with a single helix or double helix thermosensitive metal wire, and the two lead wires are fixed on the bow frame made of thicker metal, and the wire is drawn out through the insulating base , as electrical leads. This bow-type thermal wire will undergo elastic vibration when there is a slight vibration in the outside world, resulting in a large noise in the output signal. Therefore it cannot be used during exercise. In addition, the minimum cell volume of this type of thermal conductivity detector is 20 microliters, which is not suitable for use with capillary columns.

Contents of the invention

In order to overcome the defects of the prior art, the object of the present invention is to provide a cylindrical thermosensitive element wound with stretched metal thermosensitive wire, and the detection pool is a solid-state thermal conductivity detector with a coaxial structure, which can be tested at high temperature. Detection, the broadening of the chromatographic effluent band is small, the noise of the detector is low, the long-term stability of the detector performance is good, and the manufacturing process is simple.

In order to achieve the above object, the technical solution adopted in the present invention is:

A solid-state thermal conductivity detector with a cylindrical thermosensitive area, comprising a cylindrical thermosensitive element and a flow cell body. The two ends of the sensitive coating are respectively connected to the lead-out electrodes fixed at the same end of the columnar support; the inner cavity of the flow cell body is cylindrical and serves as a detection cell; the columnar thermosensitive element is embedded in the flow cell body, and the columnar support body The axis is coaxial with the axis of the detection cell, and the two ends of the flow cell body are respectively provided with a gas inlet and a gas outlet, and the gas inlet is arranged on the axis of the detection cell; the lead-out electrode is electrically connected to the external circuit through the lead-out wire.

The flow cell body is made of metal or silicon material with good thermal conductivity, the gas inlet is connected to the chromatographic column, and the gas outlet is vented; the distance between the thermosensitive electrode and the inner wall of the flow cell is 25-500 microns.

The heat-sensitive electrode refers to a heat-sensitive wire wound on the surface of a columnar support or a heat-sensitive coating coated on the surface of a columnar support; an anti-oxidation protective layer is coated on the surface of the heat-sensitive electrode;

The diameter of the heat-sensitive metal wire is 7-70 microns, which is wound on the columnar support, and the two wire ends are connected with the metal leads fixed on the lower part of the columnar support; the metal wire has a relatively high temperature coefficient of resistance and long-term Stable performance, which is nickel, platinum, rhenium-tungsten alloy or other alloys;

The heat-sensitive coating film is a heat-sensitive metal film, metal oxide film or semiconductor film, and the heat-sensitive coating film can be etched into cylindrical, comb or spiral electrodes, and the lead-out ends of the electrodes are respectively connected to the metal leads fixed on the lower part of the columnar support. connect.

The thickness of the anti-oxidation protective layer is ~2μm, which is a layer of high-temperature resistant inorganic compound or a layer of high-temperature resistant organic compound sprayed, or a layer of metal passivation layer or a gold-plated layer on the surface.

The columnar support is a cylinder or cylinder, which is made of ceramic rods, ceramic tubes, glass rods, quartz rods, glass tubes or quartz tubes; the outer surface of the columnar support is rough or has thread-shaped shallow grooves.

The thermosensitive element can be formed into a Wheatstone bridge with a pair of fixed resistors; or two pairs can be formed into a Wheatstone bridge to increase the response value and sensitivity of the detector. The inlay on the body protrudes.

The effective volume of the detection cell is 0.5-50 microliters, preferably 1-5 microliters; when used in a gas chromatographic detector, it is suitable for capillary chromatographic columns and micro-packed chromatographic columns, and the carrier gas flow rate is 0.5-30 ml/min .

The advantages of the present invention are: 1) Compared with the existing solid-state thermal conductivity detector, the thermosensitive element wound with hot wire has particularly good long-term stability, and its temperature resistance is better than that of the solid-state thermal conductivity detector made by the existing film technology. The detector is 200°C higher, so it can be used at a higher temperature to analyze components with higher boiling points, which greatly expands the scope of application; 2) Compared with the existing conventional micro-cell thermal conductivity detector, the thermal conductivity detector of the present invention Sensitive components are anti-vibration, there is no suspended metal wire, and can be used during motion; 3) The volume of the solid-state thermal conductivity detector of the present invention is an order of magnitude smaller than that of the traditional micro-cell thermal conductivity detector, and is suitable for matching with capillary chromatographic columns and Makeup gas is not needed, which significantly improves the practical sensitivity; 4) The entrance of the solid-state thermal conductivity detector of the present invention is coaxial with the detection cell, and the chromatographic outflow gas maintains a laminar flow state after entering, avoiding the direction of the entrance of the existing thermal conductivity detector and the detection The gas remixing caused by the pool direction being 90° and the concentration of components in the detection pool decaying exponentially with time cause the problem of chromatographic peak tailing; 5) the thermosensitive electrode of the present invention is evenly distributed on the outer surface of the support column, and has a large surface area, Make the incoming gas components fully contact the electrode surface. Therefore, the repeatability of the response value is better than conventional thermal conductivity detectors and existing solid-state thermal conductivity detectors.

The metal filament of the present invention is wound on a heat-insulating support round rod or a round tube, and is coated with an anti-oxidation protective film. When the temperature of the detector and the temperature of the thermosensitive electrode change within 400°C, the metal wire does not move on the cylindrical support. Shedding, the base material is not cracked or deformed. The coaxial detection cell structure adopted by the invention significantly reduces the disturbance to the air flow, increases the sensitive area for measuring the thermal conductivity change, improves the detection sensitivity and stability, and improves the broadening effect on the chromatographic band. It not only improves the overall performance of the device, but also simplifies the manufacturing process and requirements, and broadens the application field.

Description of drawings

Fig. 1 is the structural diagram of the thermosensitive element of the solid-state thermal conductivity detector of the present invention; Wherein 1 is the schematic diagram that the thermosensitive metal wire is folded on the support bar; 2 is the schematic diagram that the thermosensitive metal wire is directly wound on the support tube, Inorganic material sealing (the same below); 3 is a schematic diagram of a heat-sensitive metal film/metal oxide film/semiconductor metal compound film heat-sensitive element, and the heat-sensitive film is fixed on the support tube; 4 is the etching heat-sensitive film to form a thermistor Schematic diagram of the structure; 5 is to plate the heat-sensitive film on the support rod or tube, then perform double-helix etching, and then short-circuit the two conductive ends at the top, and weld the two conductive ends at the bottom to the fixed electrodes respectively to form a heat-sensitive resistance.

Figure 2.1 is a structural diagram of the basic structural unit of the solid-state thermal conductivity detector of the present invention; the right figure is the structure of the detector cell, and the left figure is the detector structure after the thermal sensor is embedded;

Fig. 2.2 is a schematic diagram of the structure of the four-arm solid-state thermal conductivity detector of the present invention.

Figure 3 is a schematic diagram of a measuring bridge composed of a pair of thermal elements; area 1 in the figure is the thermistor element of the measuring and reference arm, R ₁ is the measuring arm, R ₂ is the reference arm, R ₀ , R ₃ and R ₄ are bridge resistors;

Figure 4 is a schematic diagram of the measurement bridge composed of 2 pairs of heat-sensitive elements.

Fig. 5 is a spectrogram of analyzing dissolved gas samples in transformer oil when the solid-state thermal conductivity detector of the present invention is used in conjunction with a chromatographic separation column. Among them, the sample: 5ppm C ₂ H ₄ , C ₂ H ₆ , C ₂ H ₂ , C ₃ H ₈ standard gas mixture, the corresponding components of the peak number: 1: CO ₂ ; 2: C ₂ H ₄ ; 3: C _{2 H6} ; ₄ : _C2H2 ; 5: _{C3H8 .}

Detailed ways

See FIG. 1 and FIG. 2 , which are structural diagrams of the solid-state thermal conductivity detector of the present invention, including two parts of a thermal sensor 100 and a flow cell 200 . The thermosensitive element 100 consists of a cylindrical ceramic/glass/quartz rod as a support 101, a thermosensitive metal wire wound on the 101 as a thermosensitive electrode 102, or a thermosensitive metal film/metal oxide film/coated on the surface of the 101. The thermosensitive electrode 102 made of semiconductor metal compound film, the thermosensitive electrode lead 103 and the lead wire 104 are welded and connected, and the anti-oxidation protection layer 105 is composed. The thermosensitive element 100 is installed in the flow cell 200 , the base area of the 100 is covered with an elastic material 205 , and embedded in the position 204 to fix and seal. The lead-out wire 104 of the thermal element protrudes from one side and is electrically connected with an external circuit.

The cylindrical support 101 provides good strength, insulation and support with low thermal conductivity and a moderately rough surface. Make the wound or plated metal wire or metal/metal oxide/semiconductor metal compound thin-film thermosensitive electrode 102 firmly adhere to the rough surface, when the temperature changes by hundreds of degrees, it can still ensure that the thin-film thermosensitive electrode 102 can It is fixed on the surface of 101 without falling off, although the temperature expansion coefficient of the metal wire is very different from that of the support body 101, the outer coating anti-oxidation layer can fix the metal wire.

The thermosensitive metal wire can be rhenium tungsten wire, platinum wire, nickel wire and other electric heating wire with high temperature coefficient, and the thermosensitive film material can be metal film such as nickel, platinum, alloy or rhenium tungsten, or metal oxide, or semiconductor Materials such as materials with high temperature coefficient of resistance and stable performance. Referring to FIG. 3 , FIG. 4 and FIG. 5 , the thin-film thermosensitive electrode 102 is made by etching process to increase the resistance value or the temperature difference between the thermosensitive electrode and the wall of the flow cell. There can be one pair of thermal elements 100, or two pairs, as shown in FIG. 3 and FIG. 4 . Using 2 pairs of thermal elements can increase the response value and sensitivity, but increases the cell volume.

In the solid-state thermal conductivity detector of the present invention, a thermosensitive metal wire or a thermosensitive thin film resistor wound on or fixed on a cylindrical support body 101 is energized and self-heated to become a thermosensitive element 100, when the thermosensitive electrode 102 flows When the gas composition changes and the thermal conductivity of the gas changes, the degree of heat dissipation of the thermally sensitive electrode 102 changes, and the temperature of the thermally sensitive electrode 102 also changes accordingly, so that the resistance value changes accordingly. From this, changes in the gas composition can be measured.

In the thermosensitive element of the present invention, the metal wire is wound on the cylindrical support body, because the metal crystal structure is ideal, and the anti-oxidation coating is fixed, so the temperature resistance can reach 400 ° C (using platinum, rhenium tungsten wire, etc. ).

For the hollow cylindrical support 101 (implemented by a round pipe end cap), the thermally sensitive electrode 102 has a relatively high response value and response speed due to its good heat insulation effect, and is very sensitive to changes in the thermal conductivity of the gas. The solid-state thermal conductivity detector of the present invention can detect the change of thermal conductivity caused by ≤3×10 ^-6 butane gas in hydrogen gas.

Example 1

A solid-state thermal conductivity detector, on a ceramic rod 101 with a diameter of 0.6mm, a rhenium-tungsten alloy wire with a diameter of 15μm is used to wind a 100 ohm/0°C thermistor 102, and the lead wire 103 is welded to the lead wire 104, and then the The surface is coated with a low-temperature ceramic protective layer 105 with a thickness of 2 microns. This component is referred to as thermal element 100 . The two fabricated thermosensitive elements 100 are respectively embedded in two flow cells 201 to form a detection cell, which has a gas inlet 202 and a gas outlet 203 respectively. The distance between the thermal wire 102 and the wall of the detection cell is 100-200 microns. This pair of heat-sensitive elements is connected with an external circuit to form a Wheatstone bridge.

Use two elastic quartz capillary columns with a length of 20 meters and an internal diameter of 0.53mm to be connected to the two inlets of the detector respectively, one as a reference and the other as a measurement, and the inlet of the measuring capillary column is connected to the chromatographic inlet. on the sampler. Both paths are fed with carrier gas with a flow rate of 3 ml/min hydrogen. Apply a voltage to the lead wire of the detector to make the temperature of the thermosensitive electrode 60°C to 220°C higher than the detector temperature. The whole system is placed in an incubator. The sample is injected from the injector with the injection needle, and the components separated by the chromatographic column generate a signal on the detector, and the amplitude of the signal is proportional to the concentration of the component and the difference between the thermal conductivity of the component and the carrier gas. Figure 5 is the spectrum of the analyzed sample.

Example 2

Solid-state thermal conductivity detector, on a glass tube with an outer diameter of 1mm (as a support 101), a thermal electrode 102 with a resistance of 22 ohms/0°C is wound with a platinum wire with a diameter of 20 μm, and the platinum wire lead 103 is welded to a fixed lead wire 104 , coating glass glaze with a thickness of about 1 μm on the surface of the heat-sensitive area to form a protective film 105 . The two fabricated thermosensitive elements are respectively embedded in the two flow cells 201 to form two independent detection cells. The distance between the surface of the heat-sensitive area and the wall of the detection pool is 200-300 microns. The inlet 202 of the detection cell is connected to the outlet of the chromatographic column, and the outlet 203 of the detection cell is emptied. This pair of heat-sensitive elements is connected with an external circuit to form a Wheatstone bridge.

Use two micro-packed stainless steel columns with a length of 2 meters, an inner diameter of 1mm, and a chromatographic stationary phase of 100-120 mesh, which are respectively connected to the two inlets of the detector, one as a reference and the other as a measurement, and the inlet of the measuring column is connected to the detector. to the injection valve. Both paths are fed with carrier gas with a flow rate of 8 ml/min hydrogen. Apply a voltage to the lead wire of the detector to make the temperature of the thermosensitive electrode 80°C higher than the temperature of the detector. The whole system is placed in an incubator. The sample gas is injected into the sample tube from the injection valve, and the valve is turned to inject the sample. The components separated by the chromatographic column generate signals on the detector. The amplitude of the signal is proportional to the concentration of the components and the thermal conductivity of the components and the carrier gas. difference.

Example 3

On a quartz tube with an outer diameter of 0.8mm (as a support 101), a thermal electrode 102 with a resistance of 100 ohms/0°C is wound with a platinum wire with a diameter of 10 μm, and the platinum wire lead 103 is welded to a fixed lead electrode 104. The surface is coated with 0.5 μm polyimide to form the protective layer 105 . The two fabricated thermosensitive elements are respectively embedded in the two flow cells 201 to form two independent detection cells. The distance between the surface of the thermistor wire and the wall of the detection cell is 50-180 microns, the inlet 202 of the detection cell is connected to the outlet of the chromatographic column, and the outlet 203 of the detection cell is emptied. This pair of heat-sensitive elements is connected with an external circuit to form a Wheatstone bridge.

Use two elastic quartz capillary columns with a length of 30 meters and an internal diameter of 0.53mm to be connected to the two inlets of the detector respectively, one as a reference and the other as a measurement, and the inlet of the measuring capillary column is connected to the chromatographic inlet. on the sampler. Both paths are fed with carrier gas with a flow rate of 5 ml/min hydrogen. Apply a voltage to the lead wire of the detector to make the temperature of the thermosensitive electrode 150°C higher than the temperature of the detector. The whole system is placed in an incubator. The sample is injected from the injector with the injection needle, and the components separated by the chromatographic column generate a signal on the detector, and the amplitude of the signal is proportional to the concentration of the component and the difference between the thermal conductivity of the component and the carrier gas.

Example 4

A solid-state thermal conductivity detector, on a ceramic tube with a diameter of 0.5mm (as a support 101), a platinum wire with a diameter of 17 μm is used to fold a 20 ohm/0°C thermosensitive electrode 102, and the platinum wire lead 103 is welded to the lead wire 104 connection, and then coat the surface with a low-temperature ceramic protective layer 105 with a thickness of about 3 microns. The fabricated 4 pieces and 2 pairs of thermosensitive elements 100 are respectively embedded in the 2 flow cells 301 to form detection cells with gas inlets 302 and outlets 303 respectively. The distance between the thermosensitive electrode 102 and the wall of the detection cell is 50-100 microns. These 2 pairs of thermosensitive elements are connected with external circuits to form a Wheatstone bridge.

Two elastic quartz capillary columns with a length of 50 meters and an inner diameter of 0.32 mm, which are coated with a chromatographic stationary phase, are respectively connected to the two inlets of the detector, one as a reference and the other as a measurement. The inlet of the capillary column of the measuring arm is connected to the chromatographic injector. Both paths are fed with carrier gas with a flow rate of 3 ml/min hydrogen. Apply a voltage to the lead wire of the detector to make the temperature of the thermosensitive electrode 200°C higher than the temperature of the detector. The whole system is placed in an incubator. The sample is injected from the injector with the injection needle, and the components separated by the chromatographic column generate a signal on the detector, and the amplitude of the signal is proportional to the concentration of the component and the difference between the thermal conductivity of the component and the carrier gas.

Example 5

A solid-state thermal conductivity detector molds a spiral shallow groove on a glass rod with a diameter of 1.0mm (as the support body 101), and winds a 50 ohm/0°C thermosensitive electrode 102 with a platinum wire with a diameter of 22 microns, and then the platinum wire The lead 103 is welded to the lead wire 104 . The area around the platinum wire is sputtered and covered with glass with a thickness of 1-2 microns, and the protective layer 105 is stably formed after annealing. The two fabricated thermosensitive elements are respectively embedded in the two flow cells 201 to form two independent detection cells with gas inlets and outlets respectively. The distance between the surface of the thermosensitive electrode 102 and the detection cell wall 201 is 150 microns. These 2 thermistors are connected with an external bridge to form a measuring bridge.

Claims (9)

1. A solid-state thermal conductivity detector of a columnar thermosensitive area, comprising a columnar thermosensitive element (100) and a flow cell body (200), characterized in that: the columnar thermosensitive element is fixed with a thermal The sensitive electrode (102) is composed of a columnar support (101), and the two ends (103) of the metal wire or heat-sensitive coating are respectively connected to the lead-out electrodes (104) fixed at the same end of the columnar support; The inner cavity of the flow cell body is cylindrical, and the cylindrical thermosensitive element is embedded in the flow cell body, and the axis of the columnar support is coaxial with the axis of the detection cell, and the space formed by the cylindrical thermal element and the inner cavity of the flow cell is As a detection cell; a gas inlet (202) and a gas outlet (203) are respectively provided at two ends of the flow cell body, and the gas inlet is arranged on the axis of the detection cell; the lead-out electrode is electrically connected to an external circuit through a lead-out wire. 2. The solid-state thermal conductivity detector according to claim 1, characterized in that: the flow cell body is made of metal or silicon material with good thermal conductivity, the gas inlet is connected to the chromatographic column, and the gas outlet is emptied; the thermosensitive electrode The distance from the inner wall of the flow cell is 25-500 microns. 3. The solid-state thermal conductivity detector according to claim 1, characterized in that: the thermosensitive electrode is composed of a thermosensitive metal wire wound on the surface of the columnar support or a thermosensitive coating coated on the surface of the columnar support ; Coating an anti-oxidation protective layer on the surface of the thermosensitive electrode. 4. The solid-state thermal conductivity detector according to claim 3, characterized in that: the diameter of the heat-sensitive metal wire is 7-70 microns, wound on the columnar support, and the two wire ends are fixed on the columnar support The lower metal lead is connected; the metal wire has a high temperature coefficient of resistance and long-term stable performance, which is nickel, platinum, rhenium-tungsten alloy. 5. The solid-state thermal conductivity detector according to claim 3, characterized in that: the heat-sensitive coating is a heat-sensitive metal film, a metal oxide film or a semiconductor film, and the heat-sensitive coating is etched into a cylindrical shape, a comb or a spiral shaped electrodes, and the lead ends of the electrodes are respectively connected with the metal leads fixed on the lower part of the columnar support. 6. The solid-state thermal conductivity detector according to claim 3, characterized in that: the thickness of the anti-oxidation protective layer is

~2μm, which is a layer of high-temperature resistant inorganic compound or a layer of high-temperature resistant organic compound sprayed, or a layer of metal passivation layer or a gold-plated layer on the surface. 7. The solid-state thermal conductivity detector according to claim 1, characterized in that: the columnar support is a cylinder or a cylinder, which adopts ceramic rods, ceramic tubes, glass rods, quartz rods, glass tubes or quartz tubes The outer surface of the columnar support is rough or has a thread-shaped shallow groove. 8. The solid-state thermal conductivity detector according to claim 1, characterized in that: the cylindrical thermosensitive element is a pair and a fixed resistor to form a Wheatstone bridge; or two pairs form a Wheatstone bridge, so that To increase the response value and sensitivity of the detector, the lead wires protrude from the inlay of the cylindrical thermal element on the flow cell body. 9. The solid-state thermal conductivity detector according to claim 1, characterized in that: the effective volume of the detection cell is 0.5 to 50 microliters; when used in a gas chromatography detector, it is suitable for capillary chromatographic columns and micro-packed chromatographic columns , the flow rate of the carrier gas is 0.5-30 ml/min.

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