JP3800259B2 - Gas chromatograph thermal conductivity detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a highly sensitive and inexpensive thermal conductivity detector for a gas chromatograph.
[0002]
[Prior art]
FIG. 4 is an explanatory diagram of a configuration of a conventional example that is generally used in the past. For example, book title; micromachining and micromechatronics, publication date; June 20, 1992, editing author; Masayoshi Esashi, publication office; Is shown in
[0003]
In the figure, a heater 1 is obtained by sandwiching a titanium thin film 2 between silicon oxide substrates 3 and is formed in a bridge shape on a silicon pedestal 5 on a Pyrex glass substrate 4.
FIG. 5 is a detailed view of a main part of the heater 1. In FIG. 5, 11 is a heater body.
6 shows a gas flow.
[0004]
Reference numeral 7 denotes a support made of P ⁺ silicon, which supports the heater 1 on the Pyrex glass substrate 4 and also serves as a lead for the heater 1.
Reference numeral 8 denotes a terminal provided on the Pyrex glass substrate 4 and having one end connected to the column 7 and made of conductive epoxy.
[0005]
In the above configuration, the carrier gas R and the measurement fluid M are separately flowed through two of the devices configured as described above, the difference in thermal conductivity is measured, and the components of the measurement fluid are measured.
[0006]
[Problems to be solved by the invention]
However, in such a device,
(1) It has a three-layer structure of a Pyrex glass substrate 4, a silicon oxide substrate 3, and a silicon pedestal 5, and the measurement fluid M and the carrier gas R flow inside, and the measurement fluid M or the carrier gas R flows. Since it is a long multilayer film structure, a secret structure is required between each layer. Such a multilayer film structure is complicated and the apparatus is expensive.
[0007]
(2) Since the heater wires must be arranged on the intermediate layer substrate, it is necessary to secretly seal the stepped and uneven surfaces of the lead wires. A lead wire for taking out a signal to the outside through the flow of the measurement fluid M or the carrier gas R needs to be devised, the structure becomes complicated, and the apparatus becomes expensive.
[0008]
(3) Since the gas 6 flows in parallel to the plate of the heater 1, the temperature boundary layer develops from the upstream toward the downstream, so that the gas temperature on the downstream side rises. This causes a deterioration of sensitivity. The heat exchange with the gas 6 can be efficiently performed in the vicinity of the upstream end portion of the heater 1 with respect to the gas 6.
[0009]
(4) Since the heater 1 is supported in the flow path of the tunnel-like gas 6, the sensitivity characteristic of this device depends on the temperature of the flow path wall surface, and the sensitivity increases as the wall surface temperature decreases. . This is because the amount of heat generated in the heater 1 is eventually wasted on the walls, and this temperature difference is related to sensitivity.
When the size is reduced, the wall and the heater 1 are closer to each other, so that the sensitivity is further decreased. Therefore, a structure that eliminates the wall seems to be advantageous.
[0010]
The present invention solves these problems.
An object of the present invention is to provide a highly sensitive and inexpensive gas chromatograph thermal conductivity detector.
[0011]
[Means for Solving the Problems]
In order to achieve this object, the present invention provides:
(1) In a thermal conductivity detector of a gas chromatograph that detects a difference in thermal conductivity between a carrier gas and a measurement fluid,
A semiconductor heat insulating thin film body having one surface connected to one surface of the silicon semiconductor substrate, two through windows provided in the semiconductor heat insulating thin film body, and provided in parallel to the semiconductor heat insulating thin film body so as to close the through windows. A heater hole formed therein, an introduction hole for a measurement fluid provided perpendicular to the one surface of the silicon semiconductor substrate so as to face one of the through windows, and the other portion of the silicon semiconductor substrate facing the other of the through windows. A thermal conductivity detector for a gas chromatograph, comprising a carrier gas introduction hole provided vertically on one surface.
(2) The heat conductivity detector for a gas chromatograph according to claim 1, further comprising a heater wire formed in a rectangular wave shape, an alternating current wave shape or a sawtooth wave shape so as to close the through window.
(3) The gas chromatograph thermal conductivity detector according to claim 1, further comprising a heater wire formed by vapor deposition or sputtering.
Is configured.
[0012]
[Action]
In the above configuration, the measurement fluid is caused to flow through the introduction hole of the measurement fluid, and the carrier gas is caused to flow through the introduction hole of the carrier gas.
Then, the difference in thermal conductivity between the measurement fluid and the carrier gas is measured, and the components of the measurement fluid are measured.
Hereinafter, it demonstrates in detail based on an Example.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
1 is a perspective view of an essential part of one embodiment of the present invention, FIG. 2 is a front view of FIG. 1, and FIG. 3 is a cross-sectional view taken along line AA of FIG.
[0014]
In the figure, reference numeral 21 denotes a silicon semiconductor substrate.
Reference numeral 22 denotes a semiconductor heat insulating thin film body in which one surface is connected to one surface of the silicon semiconductor substrate 21. In this case, a silicon nitride film is used.
Reference numerals 23 and 24 denote two through windows provided in the semiconductor heat insulating thin film body 22.
[0015]
Reference numerals 25 and 26 denote heater wires provided in a rectangular wave shape so as to close the through windows 23 and 24 and parallel to the semiconductor heat insulating thin film body 22.
In this case, the heater wires 25 and 26 are formed on the semiconductor heat insulating thin film 22 by vapor deposition or sputtering.
Reference numeral 27 denotes a measurement fluid introduction hole provided perpendicular to one surface of the silicon semiconductor substrate 21 so as to face the through window 23.
[0016]
Reference numeral 28 denotes a carrier gas introduction hole provided perpendicularly to one surface of the silicon semiconductor substrate 21 so as to face the through window 24.
Reference numeral 29 denotes a measurement fluid introduction pipe having one end connected to the introduction hole 27.
31 is a carrier gas introduction pipe having one end connected to the introduction hole 28.
[0017]
In the above configuration, the measurement fluid M is caused to flow through the measurement fluid introduction pipe 29 and the carrier gas R is caused to flow through the carrier gas introduction pipe 31.
Then, the difference in thermal conductivity between the measurement fluid M and the carrier gas R is measured, and the components of the measurement fluid are measured.
[0018]
As a result,
(1) The flow path of the measurement fluid M or the carrier gas R is short of the introduction holes 27 and 28 and the through holes 23 and 24 provided at right angles to the layer structure of the silicon semiconductor substrate 21 and the semiconductor heat insulating thin film body 22. Since it is a flow path and is not a long multilayer film structure along the flow of the measurement fluid M or the carrier gas R as in the conventional example of FIG. 4, a confidential structure can be easily configured. Further, the structure is simplified, and an inexpensive gas chromatograph thermal conductivity detector can be obtained.
[0019]
(2) Since the heater wires 25 and 26 are arranged so as to face the flow of the measurement fluid M or the carrier gas R, the heater wires 25 and 26 are disposed at positions outside the flow of the measurement fluid M or the carrier gas R. A lead for taking out a signal from 25 and 26 may be attached to the outside. The structure is simplified and an inexpensive gas chromatograph thermal conductivity detector is obtained.
[0020]
(3) Since the heater wires 25 and 26 are arranged so as to face the flow of the measurement fluid M or the carrier gas R, the heater wires 25 and 26 do not have an upstream side or a downstream side. Therefore, unlike the conventional example of FIG. 4, the gas temperature on the downstream side cannot rise, and the heater wires 25 and 26 can efficiently exchange heat with the gas 6 and detect the thermal conductivity of the gas chromatograph with high sensitivity. A vessel is obtained.
[0021]
(4) Since the heater wires 25 and 26 are arranged so as to face the flow of the measurement fluid M or the carrier gas R, the heat exchange path with the gas 6 is shortened and depends on the temperature of the flow path wall surface. Less to do. Furthermore, since the heater wires 25 and 26 are formed on the semiconductor heat insulating thin film 22, the temperature rise of the introduction holes 27 and 28 can be ignored.
Therefore, a highly sensitive gas chromatograph thermal conductivity detector can be obtained.
[0022]
(5) If the heater wires 25 and 26 are formed in a rectangular wave shape, they can be arranged in the through windows 25 and 26 with a minimum gap, and can efficiently exchange heat with the gas 6 and have high sensitivity. The thermal conductivity detector is obtained.
[0023]
(6) If the heater wires 25 and 26 are formed by vapor deposition or sputtering, the entire thermal conductivity detector of the gas chromatograph can be manufactured by a normal semiconductor process, and the heat of the gas chromatograph which can reduce the manufacturing cost. A conductivity detector is obtained.
[0024]
In the above-described embodiment, the heater wire is described as being formed in a rectangular wave shape. However, the present invention is not limited to this, and for example, an AC wave shape or a saw wave shape may be used. In short, it is sufficient that heat exchange with the gas 6 can be efficiently performed and high sensitivity can be obtained.
[0025]
【The invention's effect】
As explained in detail above, according to claim 1 of the present invention,
(1) The flow path of the measurement fluid or carrier gas is a short flow path of introduction holes and through holes provided at right angles to the layer structure of the silicon semiconductor substrate and the semiconductor heat insulating thin film body, as in the conventional example. Since it is not a long multilayer structure along the flow of the measurement fluid or the carrier gas, a confidential structure can be easily constructed. Further, the structure is simplified, and an inexpensive gas chromatograph thermal conductivity detector can be obtained.
[0026]
(2) Since the heater wire is arranged so as to face the flow of the measurement fluid or the carrier gas, a signal is taken out from the heater wire at a position outside the flow of the measurement fluid or the carrier gas. Just install the lead for this. The structure is simplified and an inexpensive gas chromatograph thermal conductivity detector is obtained.
[0027]
(3) Since the heater wire is arranged so as to face the flow of the measurement fluid or the carrier gas, the heater wire has no upstream side or downstream side. Therefore, unlike the conventional example, the gas temperature on the downstream side cannot rise, and the heater wire can efficiently exchange heat with the gas, so that a highly sensitive gas chromatograph thermal conductivity detector can be obtained.
[0028]
(4) Since the heater wire is disposed so as to face the flow of the measurement fluid or the carrier gas, the heat exchange path with the gas is shortened and less dependent on the temperature of the flow path wall surface. Furthermore, since the heater wire is formed on the semiconductor heat insulating thin film body, the temperature rise of the introduction hole can be ignored.
Therefore, a highly sensitive gas chromatograph thermal conductivity detector can be obtained.
[0029]
According to claim 2 of the present invention, since the heater wire has a rectangular wave shape, an alternating current wave shape or a sawtooth wave shape, it can be arranged with a minimum gap in the through window, and heat exchange with gas can be performed efficiently. A highly sensitive gas chromatograph thermal conductivity detector can be obtained.
[0030]
According to claim 3 of the present invention, since the heater wire is formed by vapor deposition or sputtering, the entire thermal conductivity detector of the gas chromatograph can be manufactured by a normal semiconductor process, and the manufacturing cost can be reduced. A thermal conductivity detector for a gas chromatograph is obtained.
[0031]
Therefore, according to the present invention, a highly sensitive and inexpensive thermal conductivity detector for a gas chromatograph can be realized.
[Brief description of the drawings]
FIG. 1 is an explanatory perspective view of a main part of an embodiment of the present invention.
FIG. 2 is a front view of FIG. 1;
3 is a cross-sectional view taken along the line AA in FIG.
FIG. 4 is a diagram illustrating a configuration of a conventional example that is generally used conventionally.
FIG. 5 is a detailed explanatory diagram of the main part of FIG. 4;
[Explanation of symbols]
21 Silicon Semiconductor Substrate 22 Semiconductor Heat Insulating Thin Film Body 23 Through Window 24 Through Window 25 Heater Wire 26 Heater Wire 27 Measuring Fluid Introducing Hole 28 Carrier Gas Introducing Hole 29 Measuring Fluid Introducing Pipe 31 Carrier Gas Introducing Pipe

Claims (3)

In a thermal conductivity detector of a gas chromatograph that detects a difference in thermal conductivity between a carrier gas and a measurement fluid,
A semiconductor heat insulating thin film body having one surface connected to one surface of the silicon semiconductor substrate;
Two through windows provided in the semiconductor heat insulating thin film body;
Heater wires respectively provided in parallel to the semiconductor heat insulating thin film so as to close the through window;
A measurement fluid introduction hole provided perpendicularly to the one surface of the silicon semiconductor substrate so as to face one of the through windows;
A thermal conductivity detector for a gas chromatograph, comprising a carrier gas introduction hole provided perpendicularly to the one surface of the silicon semiconductor substrate so as to face the other of the through window. 2. The thermal conductivity detector for a gas chromatograph according to claim 1, further comprising a heater wire formed in a rectangular wave shape, an alternating current wave shape or a sawtooth wave shape so as to close the through window. The thermal conductivity detector for a gas chromatograph according to claim 1, further comprising a heater wire formed by vapor deposition or sputtering.

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