JP3978937B2 - Detector cell and optical measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detector cell having a sample flow passage of which the cross-sectional area is almost same to that of a separation capillary column, good in detection sensitivity and having productivity and an optical measuring apparatus. SOLUTION: A glass plate 1 and a silicon substrate 3 are bonded by fluoric acid. Next, the silicon substrate 3 is coated with a photoresist and an aligner is used to perform the patterning of the coated silicon substrate 3 through a photomask and the patterned silicon substrate is exposed and developed to be subjected to dry etching to form a minute flow channel groove 8 high in accuracy and having a cross section high in aspect ratio. An inlet port 2a and a discharge port 2b are provided to the glass plate 2 by a sand blasting method and the processed glass plate 2 is bonded to the silicon substrate 3 by fluoric acid. A detector cell 20 becomes a three-layered structure wherein the glass plate 2, the silicon substrate 3 and a glass plate 1 are bonded.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a detector cell for measuring absorption or emission of light in the ultraviolet or visible region, and optical measurement using this detector cell, which are used when detecting components in a very small amount of liquid sample. Relates to the device.
[0002]
[Prior art]
A detector cell for measuring the light absorption of a specimen in the ultraviolet or visible region is a method for accurately and rapidly analyzing trace components in the field of analytical chemistry (especially in the environmental analysis field, clinical field, pharmaceutical field, etc.). It is often used as a detector (for example, capillary electrophoresis (CE), liquid chromatography (LC) or flow injection analysis (FIA)). This detector cell usually has a sample inlet for introducing a liquid sample to be analyzed, a flow path for the liquid sample, and a sample outlet for discharging the liquid sample. Or it has a measurement chamber which becomes an interaction area | region with the light ray of a visible region, and it distributes and uses it at the exit of the analysis column used for the said analysis method. In addition, the measurement chamber is provided with an entrance and an exit for measurement light, and light in the ultraviolet or visible region passes through the liquid sample existing in the measurement chamber through the entrance and exits from the exit for photometry. It is detected by an optical system.
FIG. 9 shows an apparatus configuration diagram of liquid chromatography (LC) using a liquid as a mobile phase. The apparatus includes a liquid feeding unit 30, a sample injection unit 31, a separation unit 32, and a detection unit 33. The liquid feed pump 30 a sends the solution in the mobile phase tank 30 b to the sample injection unit 31 with a discharge pressure of about 70 to 400 kg / cm ² . A small amount of sample to be analyzed is injected from the septum of the sample injection unit 31 by a microsyringe, and sent to the analysis column 32a of the separation unit 32 together with the mobile phase. The separated sample enters the detector cell 33a through the analysis column 32a of the chromatographic tube filled with the porous fine particles.
FIG. 10 shows an optical measuring device using the detector cell 33a. The apparatus uses a light source 21 (normally the light emitted from the light source 21 is split into monochromatic light by a spectroscope and irradiated on the sample. Here, the light exiting the spectroscope will be described as the light source 21) and the detection of the measurement chamber 36. The measuring cell 33a, the photodetector 22, and the data analysis unit 34 are included. The measurement chamber 36 includes a detector cell 33a and a cell holder that holds the detector cell 33a. The detector cell 33a is a flow cell having a small internal volume and is usually a rectangular cell, but a special cell is also produced and can be used properly according to the purpose. The material is usually quartz glass, but there are also polystyrene resins and acrylic resins. Quartz glass can be used for both ultraviolet and visible, and others are used in the visible region. Then, the sample is separated together with the mobile phase through the analysis column 32a, and enters the detector cell 33a from the inlet channel 25. Light from the light source 21 is irradiated onto the sample in the detector cell 33a, and the sample 22 absorbs or transmits light and is detected by the photodetector 22. The detected signal is amplified and displayed and recorded by the data analysis unit 34 as absorbance or transmission percentage. The sample that has passed through the detector cell 33 a is discharged from the outlet channel 28 to the collector tank 35.
In recent years, as described in “Science, Vol. 261, p. 895-897 (1993)”, a liquid sample is introduced onto an electrophoretic member made of a glass (for example, Pyrex glass) substrate. An electrophoretic device has been developed that uses a micromachining technology based on semiconductor manufacturing technology to separate the flow channel and the flow channel for separating the liquid sample. Compared to conventional capillary electrophoresis devices, It has been reported that there are advantages that high-speed analysis is possible, solvent consumption is extremely small, and the apparatus can be miniaturized. These features make it possible to perform on-site (on-site, bedside) analysis, which has been difficult to achieve with conventional analyzers in the field of analytical chemistry described above, and for fields such as DNA analysis. It is considered promising as an advantage for screening from the viewpoint of high-speed analysis.
[0003]
[Problems to be solved by the invention]
Conventional detector cells and optical measuring devices are configured as described above. However, for example, conventional detector cells used in capillary electrophoresis devices are more common than glass capillaries that separate samples. In addition, when the volume of the measurement chamber is large and a trace amount component is analyzed, there are many cases where the separation ability of capillary electrophoresis cannot be utilized. This is because the volume of the measurement chamber is large, so that the separated trace components are remixed and diffused into the medium.
On the other hand, a method of using the separation capillary column itself as a detection cell has been studied. In this case, the sample volume required for analysis and the volume of the measurement chamber can be made extremely small, but the detection sensitivity is insufficient because the light path length is short and light that does not contribute to detection (stray light) enters the detector. Is a problem.
When a flow path is formed on a glass substrate using micromachining technology and used as an electrophoresis chip, the flow path is very small, so the optical path length is short and sufficient detection sensitivity is obtained when absorbance detection is used for the detection method. There is a problem that cannot be obtained. In order to increase the optical path length while maintaining high resolution, it is necessary to form a flow channel with a high aspect ratio (ratio of flow channel depth / width). Then, since the etching proceeds isotropically, a channel having an aspect ratio of 1 or more cannot be formed. When dry etching is used, it is possible to form a flow path with a high aspect ratio, but generally the etching rate of glass is smaller than that of silicon, and it takes a long time to form the flow path. Also, since the mask material for dry etching cannot have a high etching selectivity with glass, a thick film is required, and high-precision patterning is difficult.
The present invention has been made in view of the above circumstances, and the detection is performed so that the volume of the measurement chamber does not impair the separation ability of the various separation analysis means described above, that is, the flow path cross-sectional area is the same as that of the separation capillary column. An object of the present invention is to provide a detector cell and an optical measuring device capable of producing a cell having a flow path with a high aspect ratio with high productivity in order to realize a meter cell and improve detection sensitivity.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the detector cell of the present invention is provided with a sample inlet for introducing a liquid sample, a flow path for the introduced liquid sample, and a sample outlet for discharging the liquid sample. A detector cell that uses at least a part of a channel as a measurement chamber, wherein the detector cell is formed by bonding a silicon substrate and a glass plate B with hydrofluoric acid and etching the channel on the silicon substrate. Further, the glass substrate A provided with the sample introduction port and the sample discharge port is bonded to the silicon substrate with hydrofluoric acid, so that a flow path is formed by the glass plate A and the glass plate B. It is characterized by sandwiching and joining .
[0005]
Furthermore, the detector cell of the present invention is characterized in that the cross-sectional depth / width dimension ratio of the flow path is 1 or more.
[0006]
The optical measurement apparatus of the present invention is an optical measurement apparatus that performs optical measurement by irradiating detection light to a measurement chamber, and further includes means for positioning the detector cell.
[0007]
The detector cell and the optical measuring device of the present invention are configured as described above, and the detector cell is configured by joining a glass plate A, a silicon substrate, and a glass plate B in a three-layer structure, A portion to be a path is processed by dry etching the silicon substrate, and a glass inlet A is provided with a sample introduction port and a sample discharge port, and is formed by joining the upper and lower glass plates. And by using photofabrication technology, forming a groove having a high aspect ratio of 1 or more in the depth / width dimension ratio of the cross-sectional shape of the flow path on the silicon substrate is compared with glass. Processing is possible in a short time. The etching mask can be made of a photoresist film. As a result, a detector cell having excellent detection sensitivity can be manufactured with high productivity. In addition, since the flow channel, which is formed with high precision in both width and depth and has a cross-sectional area of approximately the same size as the separation capillary column, is used as a measurement chamber, it does not impair the separation ability of various separation analysis means. A measurement chamber with a minute volume can be realized.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the detector cell and the optical measuring device of the present invention will be described with reference to FIGS. 1A and 1B are diagrams showing a detector cell 20 of the present invention, where FIG. 1A is a plan view, FIG. 1B is a side view of the AA cross section, and FIG. 1C is a front view of the BB cross section. FIG. 2 is a diagram showing an optical measuring device using the detector cell 20 of the present invention.
Detector cell 20 is formed of three layers of glass plate 2, silicon substrate 3 and glass plate 1. The glass plate 2 is made of a material having good transparency in a wide range from the visible region to the ultraviolet region, for example, a quartz glass substrate, and includes an inlet 2a for introducing a sample and an outlet 2b for discharging the sample. The silicon substrate 3 is formed with minute channel grooves 8 used as a liquid sample channel having a width of 20 μm and a depth of 100 μm. The cross-sectional shape of the flow channel 8 is formed with a high aspect ratio such that the depth / width dimension ratio is 1 or more. As the glass plate 1, a quartz glass substrate is used similarly to the glass plate 2. The glass plate 2, the silicon substrate 3 and the glass plate 1 are joined together with a hydrofluoric acid solution, with the surfaces to be joined together. The liquid sample coming out of the analysis column is introduced from the inlet 2a of the glass plate 2, flows into the flow channel groove 8 of the silicon substrate 3, and is discharged from the outlet 2b of the glass plate 2.
[0009]
An optical measurement apparatus that performs optical measurement using the detector cell 20 includes a light source 21, a detector cell 20, a stage 23 that sets the detector cell, and a photodetector that detects light transmitted through the measurement chamber 8a. 22.
The light source 21 is a deuterium lamp, a tungsten lamp, or the like, which is split into a predetermined single wavelength by a spectroscope and irradiates the measurement chamber 8a, and emits light having a predetermined wavelength from the ultraviolet region to the visible region. be able to.
The stage 23 has a recess 24 that can accurately position the detector cell 20. By inserting the detector cell 20 into the recess 24, the inlet channel 25 formed in the stage 23 and the introduction port of the detector cell 20 are provided. 2a can be in close contact with each other, and at the same time, the outlet channel 28 formed on the stage 23 and the discharge port 2b can be in close contact with each other. Then, the light from the light source 21 becomes a position where it irradiates the measurement chamber 8a of the detector cell 20, and the detection light 11 transmitted through the measurement chamber 8a becomes a position where it enters the photodetector 22. Thereby, the optical measurement can be performed only by setting the detector cell 20 in the concave portion 24 of the stage 23.
The photodetector 22 uses a photoelectric tube, a photomultiplier tube, a photovoltaic cell, a photoconductive cell, a photodiode array detector, or the like, and detects the transmitted light through the liquid sample in the measurement chamber 8a. The signal is amplified and displayed as absorbance or percent transmission in the data analyzer.
[0010]
Next, the operation of the detector cell and the optical measuring device will be described. First, the detector cell 20 is set on the stage 23 and the analyzer is operated. The liquid sample separated from the analytical column is introduced from the inlet channel 25 to the inlet 2a of the detector cell 20 and flows into the channel groove 8 of the detector cell 20. Since a part of the channel groove 8 is used as the measurement chamber 8a, the liquid sample flows through the measurement chamber 8a having a sufficiently small volume. Since the cross-sectional shape of the channel groove 8 is formed with a high aspect ratio so that the depth / width dimension ratio is 1 or more, the optical path length becomes longer in the depth direction. Then, the light from the light source 21 enters the detector cell 20, the light passes only through the measurement chamber 8 a that is a part of the liquid sample channel groove 8, and the other light functions as a silicon substrate 3 that functions as a slit. And the detection light 11 enters the photodetector 22. For this reason, stray light can be reduced as compared with the prior art, and detection sensitivity is improved. The liquid sample that has been detected passes through the outlet channel 28 from the outlet 2b of the detector cell 20 and is discharged to an external collector tank.
[0011]
Next, the manufacturing process of the detector cell 20 will be described. The production process is performed in a silicon-glass bonding step (a), a pre-production step (b), a flow path production step (c), a glass plate processing step (d), and an assembly step (e). In the silicon-glass bonding step shown in FIG. 3, the silicon substrate 3 and the glass plate 1 are cleaned as a procedure a-1, and an oxide film 37 is formed on the surface of the silicon substrate 3 by thermal oxidation. Then, as a procedure a-2, the silicon substrate 3 and the glass plate 1 are coated with a 1% hydrofluoric acid aqueous solution on the joint surface, and both are left together at room temperature for 24 hours while applying a load of about 1 MP from the top . As a procedure a-3, the oxide film 37 on the surface of the silicon substrate 3 is removed with a hydrofluoric acid solution. In the pre-production step (b) shown in FIG. 4, as a procedure b-1, a silicon substrate 3 and a glass substrate 1 bonded together are set on a turntable, and a photoresist 6 such as AZ4620 is rotated on the surface at a rotation speed of 3000 rpm. Spin coat for 40 seconds. At this time, the thickness of the photoresist 6 is about 7 μm. The material and thickness of the photoresist 6 to be used are not particularly limited as long as the material and thickness can withstand a subsequent etching process. In step b-2, the photoresist 6 is exposed to UV light using a photomask 7 and then developed. Here, the aligner generally used for semiconductor manufacture can be used for exposure of the photoresist 6. Furthermore, the developing solution for developing the photoresist 6 is not particularly limited as long as it is used for developing the photoresist 6 to be used. In the flow path manufacturing step (c) shown in FIG. 5, the silicon substrate 3 is etched by dry etching using high frequency plasma in a mixed gas of SF ₆ , CHF ₃ and Ar as a procedure C-1. At this time, the flow channel 8 is formed. The etching gas used here is not particularly limited, and any gas may be used as long as it can process the high-aspect-ratio channel groove 8 of the silicon substrate 3. As a procedure C-2, the photoresist 6 is removed. In step C-3, the silicon substrate 3 is heated to form an oxide film 37 on the surface. In the glass plate processing step (d) shown in FIG. 6, the glass sample 2 is processed into a liquid sample introduction port 2a and discharge port 2b by processing such as sand blasting to form through holes. In the assembly step (e) shown in FIG. 7, the silicon substrate 3 and the glass plate 1 in which the sample channel grooves 8 are formed by the steps (a) to (c), and the through holes are formed by the step (d). The laminated glass plates 2 are overlapped and bonded by the same bonding method as in the silicon-glass bonding step (a), and the glass plate 2 and the silicon substrate 3 are bonded to complete the detector cell 20.
[0012]
In the above embodiment, the case where one channel is formed as the channel groove 8 in the silicon substrate 3 has been described, but a plurality of channel grooves 8 may be formed in the silicon substrate 3 as shown in FIG. A deep dry etching technique for the silicon substrate 3 has been established. For example, grooves having a width of 10 μm and a depth of 100 μm can be arranged at intervals of 20 μm. In this case, a plurality of analyzes can be performed simultaneously, and the analysis throughput can be improved.
[0013]
In addition, two intersecting channel grooves 8 can be formed on the silicon substrate 3. In this case, it is possible to inject a sample with high accuracy by using one flow path for sample introduction and the other for separation.
[0014]
【The invention's effect】
The detector cell and the optical measuring device of the present invention are configured as described above, and the groove serving as the sample flow path in the detector cell is formed on the silicon substrate using photofabrication technology. The groove width and depth are processed to a very high degree of accuracy, and the cross-sectional area of the flow path is almost the same as that of a separation capillary column, so that it can be used in a measurement chamber. A measurement room can be realized. Since the silicon substrate is processed to form a high-aspect-ratio sample flow path, the optical path length in the absorbance analysis can be increased. Furthermore, since the incident light other than passing through the flow path portion is blocked by silicon, stray light incident on the detector can be reduced, and the detection sensitivity is improved as compared with the conventional case. In addition, since the detector cell of the present invention is manufactured using semiconductor manufacturing technology, the entire detector cell is processed with small size and high precision, and a plurality of detector cells can be produced collectively. Therefore, the cost is reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a detector cell according to the present invention.
FIG. 2 is a diagram showing an embodiment of an optical measurement apparatus of the present invention.
FIG. 3 is a diagram showing a silicon-glass bonding process of the detector cell of the present invention.
FIG. 4 is a diagram showing a pre-production process of a detector cell according to the present invention.
FIG. 5 is a diagram showing a flow path manufacturing process of the detector cell of the present invention.
FIG. 6 is a diagram showing a glass plate processing step of the detector cell of the present invention.
FIG. 7 is a diagram showing an assembly process of a detector cell according to the present invention.
FIG. 8 is a diagram showing another embodiment of the detector cell of the present invention.
FIG. 9 shows a conventional liquid chromatography analyzer.
FIG. 10 is a diagram showing a conventional optical measurement apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Glass plate 2 ... Glass plate 2a ... Inlet port 2b ... Discharge port 3 ... Silicon substrate 6 ... Photoresist 7 ... Photomask 8 ... Channel groove 11 ... Detection port 20 ... Detector cell 20a ... Detector cell 21 ... Light source DESCRIPTION OF SYMBOLS 22 ... Optical detector 23 ... Stage 24 ... Recessed part 25 ... Inlet channel 28 ... Outlet channel 30 ... Liquid feeding part 30a ... Liquid feeding pump 30b ... Mobile phase tank 31 ... Sample injection part 32 ... Separation part 32a ... Analysis column 33 ... detector 33a ... detector cell 34 ... data analyzer 35 ... collector tank 36 ... measuring chamber 37 ... oxide film

Claims (3)

A sample inlet for introducing a liquid sample, a channel for the introduced liquid sample, and a sample outlet for discharging the liquid sample are provided, and at least a part of the channel is used as a measurement chamber. a detection meter cell, the detection meter cell, the silicon substrate and the glass plate B are joined hydrofluoric acid, the channel in the silicon substrate was etched, and further provided said sample inlet and said sample outlet A detector cell comprising: a glass substrate having a flow path formed by glass plate A and glass plate B sandwiched and bonded by hydrofluoric acid bonding of the obtained glass plate A to the silicon substrate . The detector cell according to claim 1 , wherein the flow path is formed by dry etching, and a cross-sectional depth / width dimension ratio is 1 or more. An optical measurement apparatus for performing optical measurement by irradiating a detection light to the measurement chamber of the detection meter cell according to claim 1 or claim 2, further comprising means for further positioning the detection meter cell An optical measuring device.

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