JP2007155674A - Microcell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact, thin-type microcell capable of easily and highly accurately measuring the concentration of liquids to be measured having a wide concentration range from low concentration to high concentration by one cell. <P>SOLUTION: The microcell is provided with both a semiconductor substrate in which a plurality of channels having different optical path lengths are formed and which is integrally provided with a photo-detection part and an electric circuit for processing detection signals outputted from the photo-detection part and a cover member pasted to the surface of the substrate. Grooves having bottoms are formed in either one of the semiconductor substrate or the photo-detection part, and the channels are formed by blocking opening parts of the grooves having bottoms in the other one of the semiconductor substrate and the photo-detection part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a microcell that can measure liquids to be measured in a wide range of concentrations, can easily calibrate measurement results, and has high measurement accuracy.

  Conventionally, as a cell of an absorptiometer, a cell made of a light-transmitting substance such as glass and having a bottomed rectangular tube shape is generally used. To measure the absorbance of a solution to be measured using such a cell, first fill the cell with a calibration solution, measure the absorbance and calibrate, then fill the same cell with the solution to be measured and measure the absorbance. ing.

  However, if one solution cell is used to measure a solution to be measured at various concentrations, the optical path length will be fixed. Dilution is required, and there is a problem that an accurate measurement value cannot be obtained with a low-concentration liquid to be measured.

  For this reason, it is necessary to prepare a plurality of cells having different optical path lengths in order to measure the absorbance of a liquid to be measured having a wide range of concentrations from low to high. However, when a plurality of cells are used, it is necessary to perform calibration for each cell, which causes a problem that the work becomes complicated.

  Therefore, the present invention is a small size that can easily and accurately measure a concentration of a liquid to be measured having a wide range from a low concentration to a high concentration in one cell by using a MEMS (Micro Electro Mechanical Systems) technology. It is also intended to provide a thin microcell.

  That is, the microcell according to the present invention includes a semiconductor substrate integrally provided with a light detection unit and an electric circuit for processing a detection signal output from the light detection unit, and a cover member attached to the surface of the substrate. A bottomed groove is formed in one of the semiconductor substrate and the cover member, and the opening of the bottomed groove is closed by the other of the semiconductor substrate and the cover member. In addition, a flow path for measuring the absorbance of the liquid to be measured is formed, and a plurality of the flow paths having different optical path lengths are formed.

  In such a case, by providing a plurality of flow paths with different lengths on the same plane, a single cell has a wide measurement range from low concentration to high concentration, and is small and thin. It is possible to obtain a light absorption cell having excellent properties. In addition, having a wide measurement range eliminates the need to adjust the concentration of the liquid to be measured, and eliminates the effects of disturbance with a single measurement, eliminating the need for conventional calibration operations, simplifying measurement operations. Measurement time can also be shortened. Furthermore, since the electrical circuit and the light detection unit are provided on the same substrate, electrical noise can be reduced when the detection signal from the light detection unit is transmitted to the electrical circuit, thus improving measurement accuracy. You can also

  When the electric circuit calculates the difference in absorbance of the same liquid to be measured measured in the flow paths having different optical path lengths, it is possible to easily eliminate the influence of disturbance.

  In order to efficiently supply the liquid to be measured to the microcell according to the present invention, the cover member is preferably provided with an inlet for the liquid to be measured that communicates with all the flow paths.

  In a general absorptiometer, the light detection unit is provided perpendicular to the light traveling direction. However, in order to make the microcell according to the present invention thinner, the light detection unit is provided on the inner surface of the flow channel. It is preferable that a reflection surface for reflecting light traveling in the longitudinal direction in the flow path and introducing the light into the light detection unit is provided in the vicinity of the light detection unit.

  When light from the light source is incident perpendicular to the longitudinal direction of the flow path of the microcell according to the present invention, the light incident perpendicular to the longitudinal direction of the flow path is reflected in the flow path. And it is preferable that the reflective surface for advancing along the longitudinal direction of the said flow path is provided.

  As described above, according to the present invention, it is possible to obtain a microcell that has a wide measurement range from a low concentration to a high concentration in a single cell, and is small and thin and excellent in handleability. Further, the measurement operation is simple and the measurement time can be shortened, and the measurement accuracy can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the microcell 1 according to the present embodiment includes a semiconductor substrate 2 and a cover member 3, and the semiconductor substrate 2 has a light detection unit 4 and a detection output from the light detection unit 4. An electric circuit 5 for processing the signal is integrally provided. The microcell 1 has, for example, a size of about 1 cm × 1 cm in length × width.

  Each part will be described below. The semiconductor substrate 2 is made of a silicon substrate or the like, and has a bottomed groove formed on the surface thereof, and the flow path through which the liquid to be measured flows is closed by the cover member 3. 21 and a discharge path 25 are formed. A reflection surface 22 inclined 45 ° upward is provided at the end of the flow channel 21 on the introduction port 24 side by a mirror treatment or the like, and a reflection surface 23 inclined 45 ° downward is provided on the end of the light detection unit 4 side. Is provided. A plurality (six in this embodiment) of the flow paths 21 and the discharge paths 25 intersect each other vertically, and L-shaped grooves similar to each other formed by the pair of flow paths 21 and the discharge paths 25 are formed. They are arranged at equal intervals. The plurality of flow paths 21 are all connected at the end on the introduction port 24 side, and the plurality of discharge paths 25 are all connected at the end on the discharge port 26 side.

  The cover member 3 is made of a glass substrate or the like, and is attached to the surface of the semiconductor substrate 2. The cover member 3 is provided with an inlet 24 for the liquid to be measured that communicates with all of the plurality of flow paths 21 and a discharge port 26 that communicates with all of the plurality of discharge paths 25 through the member.

  The light detection unit 4 is composed of a photodiode or the like, and outputs a detection signal when light enters. The light detection unit 4 is provided so that the light reflected by the reflection surface 23 is incident on the bottom of the flow path 21 near the reflection surface 23. In the present embodiment, as shown in FIG. 1, the plurality of light detection units 4 are arranged linearly.

  The electric circuit 5 includes, for example, an analog amplifier circuit, a buffer circuit, a difference circuit, and the like, and processes the detection signal output from the light detection unit 4. Specifically, the difference in absorbance at a predetermined wavelength of the same liquid to be measured measured in the flow paths 21 having different optical path lengths is calculated. Here, the said wavelength is the absorption wavelength (peak wavelength) of the measuring object in a to-be-measured liquid. If the space of the semiconductor substrate 2 permits, a computer circuit having a CPU or the like may be added, or an A / D converter may be provided integrally.

  In order to measure the concentration of the liquid to be measured, the liquid to be measured flows from the inlet 24 of the microcell 1, fills all the channels 21 with the liquid to be measured, and uses, for example, an LED that emits surface light as a light source. When the light L from the light source is incident from the end on the introduction port 24 side so as to be perpendicular to the cover member 3 and evenly in any flow path 21, the light introduced into the microcell 1. As shown in FIG. 1B, L is reflected by the reflecting surface 22, passes through the liquid to be measured filled in the flow path 21, reaches the reflecting surface 23, and is reflected again by the reflecting surface 23. Then, the light enters the light detector 4. When the light L is incident on the light detection unit 4, the light detection unit 4 outputs a detection signal, the detection signal is processed by the electric circuit 5, and the difference in absorbance at a predetermined wavelength measured in the flow paths 21 having different optical path lengths. Is calculated. Then, the correlation between the difference in absorbance and the difference in optical path length is examined, and a range in which both are proportional to each other is determined as a region where the measurement has been performed satisfactorily. By comparing this with a calibration curve prepared in advance, the concentration of the liquid to be measured can be calculated.

  When the measurement is completed, the liquid to be measured filled in the flow path 21 is discharged from the discharge port 26 via the discharge path 25.

  When the concentration of the liquid to be measured is measured by the microcell 1 according to the present embodiment, the microcell 1 includes a light source including an LED and a computer circuit including a CPU, an internal memory, an I / O buffer circuit, an A / D converter, and the like. The microcell 1 can be used as an absorbance sensor by installing the microcell 1 in a main body including an arithmetic processing unit and a display unit made up of a small liquid crystal display device or the like. The measurement data output from the microcell 1 to the main body is compared with the calibration curve data stored in advance in the arithmetic processing unit of the main body, the concentration of the liquid to be measured is calculated, and the concentration is displayed on the display unit. .

  The microcell 1 according to the present embodiment can be manufactured using the MEMS technology, and according to this method, a plurality of flow paths 21 can be formed in a lump.

  According to the present embodiment having such a configuration, a plurality of flow paths 21 having different lengths are provided on the same plane, and the light detection unit 4 is provided at the bottom of the flow path 21. It is possible to eliminate the influence, and to have a wide measurement range from a low concentration to a high concentration, and to be a small and thin microcell with excellent handleability. In addition, having a wide measurement range eliminates the need to adjust the concentration of the solution to be measured, and eliminates the effects of disturbance with a single measurement, eliminating the need for conventional calibration operations, thus simplifying the measurement operation. Measurement time can also be shortened. Furthermore, since the light detection unit 4 and the electric circuit 5 are provided on the same semiconductor substrate 2, it is possible to reduce electrical noise when a detection signal from the light detection unit 4 is transmitted to the electric circuit 5. Therefore, measurement accuracy can be improved.

  In the present embodiment, the light detection unit 4 is provided on the semiconductor substrate 2 in a substantially diagonal shape, and the flow path 21 and the discharge path 25 are formed so as to be orthogonal to each other, thereby reducing the area of the microcell 1. Since the plurality of flow paths 21 are provided maximally, the microcell 1 can be made compact regardless of the formation of the plurality of flow paths 21.

  The present invention is not limited to the above embodiment. For example, the bottomed groove may be formed in the cover member 3, and in that case, a mirror or the like may be provided as the reflecting surfaces 22 and 23.

  As shown in FIG. 2, a light guide 6 made of a light transmissive substance is provided on the side of the introduction port 24 side of the microcell 1, and light from a light source such as an LED is introduced from the light guide 6 and guided. The light may pass through the light section 6 and go straight in the flow path 21. In this case, the cover member 3 may not be light transmissive such as a glass substrate.

  In addition, as shown in FIG. 3, the light detection unit 4 made of a photodiode or the like is integrated with all the flow paths 21, and the light L from the light source is separately irradiated in each flow path 21. You may do it.

  In order to convert the light emitted from the light source into a parallel light beam having a specific wavelength, a slit, a lens, a mirror, a prism, or a diffraction grating may be appropriately disposed in the main body of the absorbance sensor.

  Further, a light source such as an LED may be embedded in the semiconductor substrate 2, the cover member 3, etc. and integrated with the microcell 1. At that time, when the light source is embedded in the side of the introduction port 24 side of the microcell 1, the reflection surface 22 is unnecessary as in the embodiment shown in FIG. 2, and the light emitted from the light source flows directly. It is introduced into the path 21 and proceeds toward the reflecting surface 23. On the other hand, when the light source is embedded below the flow path 21, the reflecting surface 22 is provided with an inclination of 45 ° downward.

  In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

  According to the present invention, it is possible to obtain a small and thin microcell that can easily and highly accurately measure the concentration of a liquid to be measured having a wide concentration ranging from a low concentration to a high concentration in one cell.

The top view (a) of microcell concerning one embodiment of the present invention, and a sectional view (b) in A-A 'line. Sectional drawing in the A-A 'line of the microcell which concerns on other embodiment of this invention. The top view of the microcell concerning other embodiments of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Microcell 2 ... Semiconductor substrate 3 ... Cover member 4 ... Photodetection part 5 ... Electric circuit 21 ... Flow path

Claims (6)

A semiconductor substrate integrally provided with a light detection unit and an electric circuit for processing a detection signal output from the light detection unit, and a cover member attached to the surface of the substrate;
A bottomed groove is formed in one of the semiconductor substrate and the cover member, and an opening of the bottomed groove is closed by the other of the semiconductor substrate and the cover member, and the liquid to be measured A flow path for measuring the absorbance of
A plurality of the flow paths having different optical path lengths are formed.   The microcell according to claim 1, wherein the electric circuit calculates a difference in absorbance of the same liquid to be measured measured in flow paths having different optical path lengths.   3. The microcell according to claim 1, wherein the cover member is provided with an inlet for a liquid to be measured that communicates with all the flow paths. The light detection unit is provided on the inner surface of the flow channel in parallel with the longitudinal direction of the flow channel,
4. The microcell according to claim 1, wherein a reflection surface is provided in the vicinity of the light detection part for reflecting light traveling in the longitudinal direction in the flow path and introducing the light into the light detection part.   The reflective surface for reflecting the light which injected into the said flow path perpendicularly | vertically with respect to the longitudinal direction of the said flow path, and advancing the inside of the said flow path along the longitudinal direction of the said flow path is provided. 4. The microcell according to 4. An absorbance sensor comprising the microcell according to claim 1, 2, 3, 4 or 5.