JP2000346793A - Detector cell and optical measuring apparatus - 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

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector cell for measuring the absorption or emission of light in the ultraviolet or visible region, which is used for detecting a component in a very small amount of liquid sample, and the detection of the cell. The present invention relates to an optical measuring device using a measuring cell.

[0002]

2. Description of the Related Art A detector cell for measuring the light absorption of a sample in the ultraviolet or visible region is used in the field of analytical chemistry (particularly, in the field of environmental analysis, clinical field, pharmaceutical field, etc.) to accurately and extremely trace components. It is often used as a detector for rapid analysis techniques (eg, capillary electrophoresis (CE), liquid chromatography (LC), flow injection analysis (FIA), etc.).
The 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. Alternatively, it has a measurement chamber serving as an interaction region with light rays in the visible region, and is used by being arranged at an outlet of an analysis column used in the analysis method. The measurement chamber is provided with an entrance port and an exit port for measuring light, and light rays in the ultraviolet or visible range pass through the entrance port, pass through a liquid sample existing in the measurement chamber, exit from the exit port, and exit from the exit port. It is detected by the 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 sending section 30, a sample injection section 31, a separation section 32, and a detection section 33. The liquid sending pump 30a transfers the solution in the mobile phase tank 30b to the sample injection section 3 at a discharge pressure of about 70 to 400 kg / cm ^2.
Send to 1 A small amount of sample to be analyzed is injected from the septum of the sample injection unit 31 with a micro syringe, and sent to the analysis column 32a of the separation unit 32 together with the mobile phase. Through an analytical column 32a of a chromatographic tube filled with porous fine particles,
The separated sample enters the detector cell 33a. FIG. 10 shows an optical measurement device using the detector cell 33a. The apparatus includes a light source 21 (normally, the light emitted from the light source 21 is split into monochromatic light by a spectroscope and is irradiated on the sample, but the light emitted from the spectroscope is described as the light source 21 here) and the detection of the measurement chamber 36. It comprises a total cell 33a, a photodetector 22, and a data analyzer 34. The measurement chamber 36 includes a detector cell 33a and a cell holder for holding the detector cell 33a. Detector cell 33a
Is a flow cell having a small internal volume, which is usually of a square shape, but also has a special shape, which can be used depending on 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 light, while others are used in the visible region. Then, the sample is separated through the analysis column 32a together with the mobile phase, and enters the detector cell 33a from the inlet channel 25. The light from the light source 21 is applied to the sample in the detector cell 33a, absorbed or transmitted by the sample, and detected by the photodetector 22. The detected signal is amplified and displayed and recorded by the data analysis unit 34 as an absorbance or a transmission percentage. The sample that has passed through the detector cell 33a is discharged from the outlet channel 28 to the collector tank 35. Recently, “Science, Vol. 261, p.
895-897 (1993) ", a flow path for introducing a liquid sample and a liquid sample for separating the liquid sample on an electrophoresis member made of a glass (for example, Pyrex glass) substrate. Electrophoresis devices with flow paths formed using micromachining technology based on semiconductor manufacturing technology have been developed.Compared with conventional capillary electrophoresis devices, high-speed analysis is possible and solvent consumption is extremely low. It has been reported that it has the advantage that the device can be downsized. 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 in the field of DNA analysis, etc. From the viewpoint of high-speed analysis, it is considered promising as an advantage for screening.

[0003]

The conventional detector cell and the optical measuring device are configured as described above. However, the conventional detector cell used in, for example, a capillary electrophoresis device is a method in which a sample is used for a sample. In general, the volume of the measurement chamber is larger than that of the glass capillary to be separated, and in the case of analyzing a trace component, the separation ability of the capillary electrophoresis method cannot often be utilized. This is because the volume of the measurement chamber is large, so that the separated trace components are remixed or diffused into the medium. On the other hand, a method of using a separation capillary column itself as a detection cell has been studied. In this case, the sample volume and the volume of the measurement chamber required for the analysis can be extremely small, but the optical path length is short,
The problem is that the detection sensitivity is insufficient because light (stray light) that does not contribute to detection enters the detector. 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 when using absorbance detection for the detection method, the optical path length is short and sufficient detection sensitivity is obtained. There is a problem that can not be obtained. In order to increase the optical path length while maintaining high resolution, it is necessary to form a flow path having a high aspect ratio (ratio of flow path depth / width). In this case, since the etching proceeds isotropically, a flow path having an aspect ratio of 1 or more cannot be formed.
When dry etching is used, a channel having a high aspect ratio can be formed. However, in general, the etching rate of glass is lower than that of silicon, and it takes a long time to form the channel. Further, since a mask material for dry etching cannot obtain a large etching selectivity with glass, a thick film is required, and high-precision patterning is difficult. The present invention has been made in view of such circumstances, and has a detection chamber in which the volume of the measurement chamber does not impair the separation capability of the various separation and analysis means described above, that is, the cross-sectional area of the flow channel is substantially the same as that of the separation capillary column. Total cell, and
An object of the present invention is to provide a detector cell and an optical measuring device which can produce a cell having a channel having a high aspect ratio with high productivity in order to improve detection sensitivity.

[0004]

To achieve the above object, a detector cell of the present invention comprises a sample inlet for introducing a liquid sample, a flow path for the introduced liquid sample, and a liquid sample discharge port. The detector cell provided with a sample outlet to be used and using at least a part of the area of the flow path as a measurement chamber, the detector cell has a three-layer structure of a glass plate A, a silicon substrate, and a glass plate B. The glass plate A is provided with the sample introduction port and the sample discharge port,
The silicon substrate is provided with the flow path for the liquid sample.

Further, the detector cell of the present invention is characterized in that the cross-sectional shape of the flow path has a depth / width dimensional ratio of 1 or more.

The optical measuring device according to the present invention comprises a light source for irradiating the flow path with detection light from the glass plate A side of the detector cell, and a detection light from the glass plate B surface side of the detector cell. It comprises a photodetector for measurement and a means for positioning the detector cell, and performs optical measurement by the detector cell.

The detector cell and the optical measurement device of the present invention are configured as described above, and the detector cell is formed by joining a glass plate A, a silicon substrate, and a glass plate B in a three-layer structure, A portion to be a flow path of the sample is processed by dry etching the silicon substrate, and a sample introduction port and a sample discharge port are provided in a glass plate A on the upper portion thereof, and formed by joining the upper and lower glass plates. You. By using the photofabrication technology, forming a groove having a depth / width dimensional ratio of the cross-sectional shape of the flow path on the silicon substrate of 1 or more is higher than that of glass. Processing is possible in a short time. The etching mask can be formed using a photoresist film. As a result, a detector cell having excellent detection sensitivity can be manufactured with high productivity. In addition, since the width and depth formed with high precision are very small and the cross-sectional area of the flow path is almost the same as that of the separation capillary column, the separation capacity of various separation and analysis means is not impaired. Thus, a measurement chamber having a small volume can be realized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a detector cell and an optical measuring device according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a detector cell 20 of the present invention,
(A) is a plan view, (b) is a side view of AA section, (c)
Shows a front view of a BB section. FIG. 2 is a diagram showing an optical measurement device using the detector cell 20 of the present invention. The detector cell 20 is formed of three layers of a glass plate 2, a silicon substrate 3, and a glass plate 1. The glass plate 2 is made of a material having a high transmittance in a wide range from the visible region to the ultraviolet region, for example, a quartz glass substrate, and has an inlet 2a for introducing a sample.
And a discharge port 2b for discharging a sample. The silicon substrate 3 is formed with a micro channel groove 8 having a width of 20 μm and a depth of 100 μm used as a liquid sample channel.
The cross-sectional shape of the flow channel 8 is formed with a high aspect ratio so that the dimensional ratio of depth / width becomes 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 tightly joined with a hydrofluoric acid solution with their 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 8 of the silicon substrate 3, and is discharged from the outlet 2b of the glass plate 2.

An optical measuring apparatus for performing optical measurement by using the detector cell 20 detects a light source 21, a detector cell 20, a stage 23 for setting the detector cell, and light transmitted through the measuring chamber 8a. And a photodetector 22. As the light source 21, a deuterium lamp, a tungsten lamp, or the like is used, and the light source 21 is separated into a predetermined single wavelength by a spectroscope,
By irradiating the measurement chamber 8a, light of a predetermined wavelength from the ultraviolet region to the visible region can be emitted. Stage 23
Has a concave portion 24 for accurately positioning the detector cell 20, and by inserting the detector cell 20 into the concave portion 24, the inlet channel 25 formed in the stage 23 and the inlet 2a of the detector cell 20 Stage 23
The outlet channel 28 formed at the bottom and the outlet 2b can be in close contact with each other. The light from the light source 21 illuminates the measurement chamber 8a of the detector cell 20 and the detection light 11 transmitted through the measurement chamber 8a is incident on the photodetector 22.
Thereby, the detector cell 20 is placed in the concave portion 24 of the stage 23.
By simply setting, optical measurement becomes possible. The photodetector 22 includes a phototube, a photomultiplier, a photocell, a photoconductive cell,
Measurement room 8a using photodiode array detector etc.
Transmitted through the liquid sample to detect transmitted light. The signal is amplified and displayed in the data analyzer as absorbance or percent transmission.

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 and introduced out of the inlet channel 25 is introduced into the inlet 2a of the detector cell 20, and the detector cell 20
Flow channel 8. A part of the flow channel 8 is connected to the measuring chamber 8a.
Therefore, the liquid sample flows through the measurement chamber 8a having a sufficiently small volume. The cross-sectional shape of the flow channel 8 is depth /
Since it is formed with a high aspect ratio so that the width dimension ratio becomes 1 or more, the optical path length increases 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 8a which is a part of the liquid sample flow channel 8, and the other light is the silicon substrate 3 functioning as a slit. The detection light 11 enters the photodetector 22. For this reason, stray light can be reduced as compared with the related art, and the detection sensitivity is improved. After the detection, the liquid sample passes through the outlet channel 28 from the outlet 2b of the detector cell 20, and is discharged to an external collector tank.

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, as step a-1, the silicon substrate 3 and the glass plate 1 are washed, and an oxide film 37 is formed on the surface of the silicon substrate 3 by thermal oxidation. Then, as a procedure a-2, a 1% hydrofluoric acid aqueous solution is applied to the bonding surface of the silicon substrate 3 and the glass plate 1, and the two are combined at room temperature while applying a load of about 1 MP from above.
Leave for 4 hours. Here, the hydrofluoric acid bonding method is used, but another method, for example, a method by direct bonding may be used. Procedure a-
As 3, the oxide film 37 on the surface of the silicon substrate 3 is removed with a hydrofluoric acid solution. In the pre-manufacturing step (b) shown in FIG. 4, the procedure in which the silicon substrate 3 and the glass substrate 1 are bonded to each other is set on a turntable as step b-1, and a photoresist 6 is formed on the surface.
For example, AZ4620 is spin-coated at a rotation speed of 3000 rpm 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, and may be any material and thickness that can withstand a subsequent etching step. As step b-2, the photoresist 6 is exposed to UV light using the photomask 7, and then developed. Here, for the exposure of the photoresist 6, an aligner generally used in semiconductor manufacturing can be used. Further, a developing solution for developing the photoresist 6 includes:
There is no particular limitation as long as it is used for developing the photoresist 6 to be used. In the flow channel manufacturing step (c) shown in FIG. 5, SF _{6 is used} as the procedure C-1.
The silicon substrate 3 is etched by dry etching using high frequency plasma in a mixed gas of CHF ₃ and Ar and Ar. At this time, the flow channel 8 is formed. The etching gas used here is not particularly limited,
Any gas can be used as long as it can process the high aspect ratio flow channel 8 of the silicon substrate 3. In step C-2, the photoresist 6 is removed. Then, as 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 inlet 2a and the outlet 2b of the liquid sample are processed by, for example, sandblasting the glass plate 2 to form a through hole. In the assembly step (e) shown in FIG. 7, (a) to (c)
The silicon substrate 3 and the glass plate 1 in which the flow channel 8 for the sample is formed in the step (d) and the glass plate 2 in which the through hole is formed in the step (d) are overlapped, and the same as the silicon-glass bonding step (a) And the glass plate 2 and the silicon substrate 3 are bonded to each other to complete the detector cell 20.

In the above embodiment, a case was described in which one flow path was formed as the flow groove 8 in the silicon substrate 3. However, as shown in FIG. 8, a plurality of flow grooves 8 were formed in the silicon substrate 3. Can also. 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 formed at intervals of 20 μm. In this case, a plurality of analyzes can be performed simultaneously, and the throughput of the analysis can be improved.

Also, two intersecting flow channels 8 can be formed on the silicon substrate 3. In this case, high-precision sample injection is possible by using one flow path for sample introduction and the other for separation.

[0014]

The detector cell and the optical measuring device of the present invention are configured as described above, and the groove serving as a sample flow path in the detector cell is formed on a silicon substrate by using a photofabrication technique. The width and depth of the grooves are very small and highly precise, and the cross-sectional area of the channel is almost the same as that of the separation capillary column. Thus, a measurement chamber having a small volume can be realized. Since the silicon substrate is processed to form a flow path for the sample having a high aspect ratio, the optical path length in the absorbance analysis can be increased. Further, since the incident light other than that 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 related art. 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 accuracy,
Further, since a plurality of detector cells can be produced collectively, the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of a detector cell of the present invention.

FIG. 2 is a diagram showing an embodiment of the optical measuring device of the present invention.

FIG. 3 is a view showing a silicon-glass bonding step of the detector cell of the present invention.

FIG. 4 is a view showing a pre-fabrication process of the detector cell of the present invention.

FIG. 5 is a view showing a flow channel manufacturing process of the detector cell of the present invention.

FIG. 6 is a view showing a glass plate processing step of the detector cell of the present invention.

FIG. 7 is a view showing an assembly process of the detector cell of 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 device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass plate 2 ... Glass plate 2a ... Inlet 2b ... Outlet 3 ... Silicon substrate 6 ... Photoresist 7 ... Photomask 8 ... Channel groove 11 ... Detection port 20 ... Detector cell 20a ... Detector cell 21 ... Light source Reference Signs List 22 photodetector 23 stage 24 recess 25 inlet flow path 28 outlet flow path 30a liquid feed section 30a liquid feed pump 30b mobile phase tank 31 sample injection section 32 separation section 32a analysis column 33 Detector 33a Detector cell 34 Data analyzer 35 Collector tank 36 Measurement chamber 37 Oxide film

Claims (3)

[Claims] A sample introduction port for introducing a liquid sample;
A channel for the introduced liquid sample and a sample outlet for discharging the liquid sample are provided, and in a detector cell using at least a part of the channel as a measurement chamber, the detector cell is made of glass. Plate A, a silicon substrate, and a glass plate B are joined in a three-layer structure, the glass plate A is provided with the sample inlet and the sample outlet, and the silicon substrate is provided with the flow path for a liquid sample. Detector cell, characterized in that: 2. The detector cell according to claim 1, wherein a depth / width dimension ratio of a cross-sectional shape of the flow path is 1 or more. 3. An optical measuring apparatus using the detector cell according to claim 1 or 2, wherein the glass plate A
A light source that irradiates the flow path with detection light from the surface side, a photodetector that measures the detection light from the glass plate B side of the detection meter cell, and a unit that positions the detection meter cell; An optical measuring device for performing optical measurement by a measuring cell.