JP2008051608A - Optical cell for concentration measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simplify and low price optical cell securing measuring precision and measuring range capable of easily forming a structure corresponding to a small amount of flow and not causing stagnation and an analyzer using it. <P>SOLUTION: This cell arranged between a light source 31 and a photodiode 32 receiving an emitted measuring light 2 from the light source 2 comprises a light introduction mouth 121 introducing the measuring light 2, a light derivation mouth 131 deriving the measuring light and one channel 11 to flow the fluid of the measuring object crossing a plurality of times the measuring light 2 which passes from the light introduction mouth 121 to the light derivation mouth 131. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a measuring apparatus for measuring the concentration of hemoglobin or the like and an optical cell used therefor.

  Conventionally, as shown in Patent Document 1, a measuring apparatus has been developed in which a measurement target fluid containing hemoglobin or the like is allowed to flow through a transparent cell, and its concentration or the like is measured from its light transmittance. As a typical optical cell used in such a measuring apparatus, as shown in FIG. 5, the fluid to be measured is introduced from one thin fluid inflow path to one end of a thick columnar cell body, and to the other end. Some are derived from connected fluid outlets.

  In such a case, in order to ensure a sufficient optical path length and ensure measurement accuracy and measurement range, light is emitted along the flow direction of the cell body, that is, from one end of the cell body to the other end. The concentration of the fluid to be measured is measured based on the permeability.

  However, as apparent from FIG. 5, in this optical cell, the cell body is formed thicker than the fluid inflow path and the fluid outflow path, and the flow path diameter greatly changes at the connection portion, so the fluid flow changes greatly. . In addition to this, the shape of the cell body may be angular, and stagnation is likely to occur at the connection between the cell body and the fluid inflow path, the fluid outflow path, and the corner of the cell body. In this stagnation, bubbles and fluids to be measured in the past tend to accumulate, which potentially has the problem of adversely affecting the measurement. In particular, when the flow rate of the fluid to be measured is very small, the influence of stagnation is large, which causes a serious error.

  In order to solve this problem, for example, the corner of the cell may be eliminated, and the fluid inflow path may be thickened to the same diameter as the cell main body so that stagnation does not occur. However, this increases the volume of the cell. Therefore, it becomes difficult to measure a fluid having a small flow rate such as hemoglobin. On the other hand, if the cell body is thinned to the same diameter as the fluid inflow path, light is transmitted along the longitudinal direction inside the thin cell body having a curved surface because there are no corners, resulting in structural difficulties. It is easy and practicality is poor.

  The point is that the above-mentioned problem occurs because the conventional one transmits light along the flow of fluid.

However, if light is simply transmitted so as to be orthogonal to the fluid flow, a sufficient optical path length cannot be ensured and measurement accuracy and measurement range cannot be ensured.
JP 2004-257768 A

  The present invention has been made in order to solve the above-mentioned problems. In addition to ensuring a sufficient optical path length to ensure measurement accuracy and a measurement range, it can be easily applied to a structure corresponding to a small flow rate. The main object is to provide a low-cost optical cell and a measuring apparatus using the same.

  That is, the optical cell according to the present invention is interposed between a light source and a light receiving system for receiving measurement light emitted from the light source, and guides the measurement light and an optical entrance for introducing the measurement light. It has a light path and a single flow path for flowing the measurement target fluid that crosses the measurement light passing from the light entrance to the light exit a plurality of times.

  Here, the measurement light is light that exits from the light source and reaches the light receiving system (detector), and is refracted between the time when it first enters the optical cell and the time when it finally exits from the optical cell. Even if it is changed, it is light that has been reflected and has not changed its traveling direction. The term “one channel” includes a case where the branched channel does not intersect with the measurement light even if there is a branch.

  With such an optical cell, even if it is a narrow flow path, the flow path intersects the measurement light as many times as necessary, and the optical path length, which is the distance that the measurement light passes through the fluid to be measured, is accurately measured by the detector. Since it can be made long enough to be detected, measurement accuracy and measurement range can be secured. In addition, since the flow path can be narrowed as described above, the volume of the flow path does not increase, and measurement can be performed even when the amount of fluid to be measured is very small.

  Further, as described later, for example, the stagnation can be prevented from occurring only by adopting a structure in which the flow path cross section is the same and the flow path is formed only from the straight line portion and / or the smooth curved portion. Measurement error can be suppressed. In addition, the structure realized in this way is so simple that only one string-like flow path is partially bent, so that the structure is not complicated and the cost is not increased. . Moreover, it is not restricted to such a structure, It is also easy to set it as the various aspects according to the property of the fluid to be measured, the shape of the whole cell, etc. In other words, the restriction on the flow path is less than that of the conventional one, and the effect that the degree of freedom in design can be greatly improved is also obtained.

  In order to increase the measurement accuracy, it is desirable to have a structure that does not cause stagnation in the entire flow path. As a result, not only from the stagnation of the area where the light in the flow path (light irradiation area) stagnation, but also from the stagnation on the flow path other than the light irradiation area, air bubbles and past measurement target fluids flow into the light irradiation area of the flow path In addition to sampling measurement (batch measurement), measurement errors in continuous measurement can be reduced as much as possible.

  As a structure for that purpose, for example, it is desirable that the cross-sectional shape of the flow path is the same from the front end to the end of the flow path. If the flow path has an equal cross section, the manufacturing process may be simplified. Here, the cross section of the flow path is a cross section of the flow path perpendicular to the flow direction of the fluid as a whole. Shape includes shape and dimensions.

  As another structure, the inner wall of the flow path may change smoothly so as to draw a streamline shape, for example.

  As described above, the entire flow path may be structured without stagnation, but in some cases, it may be structured such that there is no stagnation on the upstream side at least including the light irradiation region. An effect can be produced.

  What is necessary is just to comprise so that the said flow path may cross the said measurement light perpendicularly as a further device for making a measurement precision high. In such a case, since the measurement light is not refracted, it always goes straight across the flow path on the same optical path regardless of the difference in the refractive index of the fluid to be measured. Therefore, the measurement light always reaches the same position of the light receiving system, and a measurement error due to the deviation of the arrival position can be avoided.

  If the optical cell is plate-shaped, it is possible to easily form a flow path by forming a groove in the plate-shaped member and covering the plate-shaped member, and manufacturing of the optical cell is facilitated. Further, since the optical cell can be made thin, it is useful for a portable measuring apparatus.

  When measuring the concentration of hemoglobin, only a small amount of fluid can be obtained, and it is easily affected by stagnation. Therefore, the effect of the present invention is particularly remarkable.

  As described above, according to the present invention, the measurement accuracy and the measurement range can be ensured, the flow path can be narrowed, the structure does not cause stagnation, an optical cell having a high degree of design freedom, and a measurement apparatus using the same. Can provide.

  Next, an embodiment of an optical cell of the present invention and a measuring apparatus using the same will be described with reference to the drawings.

  FIG. 1 schematically shows an entire optical cell 1 and a measuring apparatus 3 including the same according to the present embodiment. The measuring device 3 detects the measuring light 2 emitted from the light source 31 and passed through the fluid to be measured including hemoglobin contained in the optical cell 1 by the detector 32 constituting the light receiving system, and the detected measuring light. It is used for the measurement for obtaining the concentration of hemoglobin from the intensity of 2.

  First, the structure of the optical cell 1 according to the present embodiment will be described with an example of a manufacturing method.

  As shown in FIGS. 2 to 4, first, a bottomed groove 03 is provided on one surface 011 of the rectangular plate-shaped main body member 01 by etching or mechanical means. Since the main body member 01 is required to transmit at least the light 2 used for the measurement, it is made of, for example, a transparent acrylic resin having a light transmitting property.

  Next, from the surface 011 side of the main body member 01, a rectangular sheet-like lid member 02 having the same planar dimensions as the main body member 01 is covered, and the flow path 11 is formed by closing the opened groove 03, thereby forming a flat plate shape. The optical cell 1 can be formed. The fluid inlet 111 and the fluid outlet 112 are formed by providing holes in the lid member 03 at the positions of the front end and the end of the flow path 11. The fluid inlet 111 and the fluid outlet 112 are on the same surface of the optical cell 1 and are formed so as to be biased toward the same side.

  The one flow path 11 includes a fluid inlet 111, a fluid outlet 112, and an intermediate portion 113 sandwiched between them. Further, the intermediate portion 113 has a plurality of straight portions 1131 that are parallel to each other and have the same length, and a semicircular curved portion 1132 that smoothly connects the straight portions 1131, and the flow path 11 is folded and bent. .

  The cross section of the groove is a square with a width of 1 mm and a depth of 1 mm, and the cross sections of the straight portion 1131 and the curved portion 1132 of the flow path 11 to be formed are also square. Since the straight line portions 1131 are parallel and have the same width, the optical path length can be easily calculated. In other words, the optical path length is obtained by multiplying the number of times the flow path has crossed the measurement light 2 by the width of the flow path. In this embodiment, the length of the optical path is 5 mm, and the width is 1 mm. Further, the side surface of the straight line portion 1131 is parallel to the side surface of the optical cell 1.

  At least a part of the light 2 emitted from the light source 31 enters the optical cell from one side surface 12 of the optical cell 1, and is reflected from the other side surface 13 facing the one side surface 12 of the optical cell 1 without being reflected inside the optical cell 1. It leaves the optical cell 1 and reaches the detector (measurement light 2). A portion where the measurement light 2 is incident on the optical cell 1 is a light entrance 121, and a portion where the measurement light 2 is emitted is a light exit 131. The measurement light 2 passes through the optical cell 1 and the straight line connecting the light entrance 121 and the light exit 131 is the optical axis 21 of the measurement light. The straight portion 1131 of the flow path 11 of the optical cell 1 crosses the optical axis 21 of the measurement light 2 vertically. That is, since the plurality of straight line portions 1131 are parallel, if one straight line portion 1131 crosses the optical axis 21 vertically, the other straight line portion 1131 also crosses the optical axis 21 vertically.

  A hemoglobin concentration apparatus 3 using the optical cell 1 of this embodiment will be described. The measuring apparatus 3 includes the optical cell 1 described above, an LED (light source) 31 for allowing the measuring light 2 to enter the optical cell 1, a photodiode 32 that is a detector that receives the measuring light, an arithmetic processing unit 33, ,have.

  The LED 31 and the photodiode 32 are on a straight line perpendicular to the one side surface 12 of the optical cell 1, the LED 31 is disposed on the one side surface 12 of the optical cell 1, and the photodiode 32 is disposed on the other side surface 13 facing the one side surface 12. Arranged as desired, the optical cell 1 is sandwiched between the two.

  The arithmetic processing unit 33 performs processing described later.

  Operation | movement of the measuring apparatus 3 which has the optical cell 1 which concerns on this embodiment is demonstrated. The measurement target fluid S is supplied from the fluid supply system 34 to the optical cell 1, flows along the flow path 11 of the optical cell 1, and is discharged to the fluid discharge system 35. The measurement is performed in a state where the measurement target fluid S including, for example, hemoglobin is flowing through the flow path 11.

  When light is emitted from the LED 31, the measurement light 2 passes through the optical cell 1 and enters the photodiode 32 as described above. The photodiode 32 converts the intensity of the received measurement light 2 into an electrical signal. The arithmetic processing unit 33 receives this signal. When passing through the optical cell 1, the linear portion 1131 of the flow path 11 in which the measurement target fluid S is flowed intersects the measurement light 2 perpendicularly several times, and the measurement light 2 is absorbed by the measurement target fluid S. The intensity of the measurement light 2 detected by the photodiode 32 is smaller than the case where, for example, water that does not absorb the measurement light 2 is flown into the water 11 and does not contain hemoglobin. From this difference, the hemoglobin concentration in the fluid S to be measured can be obtained.

  In the optical cell 1 according to the first embodiment, the straight portion 1131 and the curved portion 1132 of the flow path 11 have the same square cross section, and the straight portion 1131 and the curved portion 1132 are smoothly connected. Since stagnation does not occur, bubbles and measurement target fluid S do not stay and measurement accuracy is improved. This is particularly effective when measuring temporal changes. Moreover, the optical cell 1 can be easily cleaned. Further, by increasing the number of straight portions 1131 of the flow path 11, the flow path 11 through which the measurement light 2 and the measurement target fluid S pass can be crossed as many times as necessary. (Passing length) can be increased, and sufficient absorbance can be obtained even when the concentration of the fluid S to be measured is low, and the measurement accuracy and measurement range can be ensured.

  Further, even if the flow path 11 is made thinner, by setting the number of times that the flow path 11 crosses the measurement light 2 to an appropriate number, sufficient absorbance can be obtained, and measurement accuracy and measurement range can be ensured. Since the channel 11 is formed by digging the groove 03 in one plate-like member 01 and covering the channel member 11 with the lid member 02, the manufacture of the cell is facilitated. Since the fluid inlet 111 and the fluid outlet 112 are formed so as to be biased toward the same side of the optical cell 1, for example, when the optical cell 1 is mounted in a cartridge so as to slide into the measuring device 3 The optical cell 1 can be easily attached to and detached from the device 3.

  As described above, in the conventional optical cell, light cannot be incident vertically while avoiding stagnation. In a conventional optical cell, it is possible to design a curved surface that eliminates stagnation and eliminates corners where stagnation occurs. In this case, however, light is not stagnation, but is incident on the bent portion. The light is reflected or refracted by the bent boundary surface, and the intensity of the light detected by the detection unit becomes small, so that the amount of light necessary for measurement cannot be secured, and the measurement accuracy is lowered. In the optical cell 1 of the first embodiment, the opposing side surfaces of the linear portion 1131 of the flow path 11, that is, the side surfaces on which the measurement light 2 enters and exits are parallel to each other and further to the side surface of the optical cell 1. The measurement light can be incident so that the incident angle and the emission angle of the light 2 with respect to the flow path forming member, and the incident angle and the emission angle with respect to the light flow path are perpendicular. Incidentally, the side surfaces of the curved portion 1132 are also parallel here. In this way, since the measurement light 2 is not scattered due to refraction or reflection due to the measurement light 2 entering the curved surface, the intensity of the measurement light 2 is not easily reduced, and the amount of light necessary for measurement can be secured, thereby increasing the measurement accuracy. be able to.

  Since the side surfaces of the straight line portion 1131 are parallel, the measuring light 2 incident perpendicularly into the surface can travel straight. Since the side surfaces of the straight line portion 1131 are parallel, even if the position of the light source is shifted relative to the optical cell, the optical path length of the measurement light 2 is the same and does not affect the density measurement.

  Note that the present invention is not limited to the present embodiment.

  In the above embodiment, the cross-sectional shape of the flow path 11 is made substantially the same so that the entire flow path 11 does not stagnate, but other than that, the flow path is gradually expanded or contracted. The wall surface may be streamlined, that is, the flow path may be curved smoothly without being bent, so that stagnation does not occur in the entire flow path. Further, even if the structure does not cause stagnation in the entire flow path, as shown in FIG. 6, the flow path may not have a structure in which stagnation occurs upstream from the portion that finally traverses the optical path. Any cross-sectional shape may be used as long as it is the same and is linearly or smoothly curved. Even if it comprises in this way, the optical cell which does not receive to the influence of stagnation can be obtained.

  Further, as shown in FIG. 6, a structure in which stagnation does not occur at least in a region where the flow path and the measurement light intersect may be used. Even if it comprises in this way, the optical cell which does not receive to the influence of stagnation can be obtained.

  In the above embodiment, the single flow path 11 crosses the measurement light 2 vertically a plurality of times by a plurality of parallel straight portions 1131 having the same width, but the width may be different, as shown in FIG. In addition, the straight part may not be parallel, the measurement light may be crossed not vertically, and the measurement light may be crossed by a curved surface instead of the straight part. What is necessary is just to cross the measurement light a plurality of times. With such an optical cell, the optical path length can be increased by changing the number of times of traversing, and the measurement accuracy and measurement range can be ensured. Even if the flow path is narrow, it is possible to cope with a low flow rate by setting the number of crossings to an appropriate number. Furthermore, the above-described design that does not cause stagnation can be easily performed. Further, the flow path only needs to cross the measurement light and does not need to be parallel to the measurement light, so the degree of freedom of the flow path is increased.

  In the above-described embodiment, the optical cell 1 has a groove 03 formed in one member 01 and covered with the sheet-like member 02 to form a flow path with two members. However, the present invention is not limited to this manufacturing method. The provided members may be combined, or the flow path may be formed in one member without a lid. In this embodiment, the optical cell is a flat plate, but the optical cell may have any outer shape. For example, it may be tubular.

  In the embodiment, the LED 31 is used as the light source. However, the present invention is not limited to this, and an appropriate light source can also be used. The light source includes a point light source and a surface light source, and the light may be parallel light or light diffused from one point. It is sufficient that at least a part of these lights enter the optical cell, pass through the optical cell without reflection, and reach the detector. Further, instead of the detector, a detection system may be provided in which an optical fiber is provided to guide light to a remote detector.

  Although the measurement target fluid is measured in a state where the fluid is flowing, the measurement may be performed in a state where the flow is stopped.

  In the above-described embodiment, the fluid containing hemoglobin in blood as the measurement target fluid has been described. However, fluid other than the fluid containing hemoglobin may be measured. For example, metal ions in the solution are colored with a color former, Metal ions may be measured. The fluid to be measured includes liquid and gas.

  In addition, the present invention may be combined with some or all of the above-described embodiments and modifications as appropriate, and various modifications may be made without departing from the spirit of the invention.

Schematic of a hemoglobin concentration measuring apparatus according to an embodiment of the present invention The top view of the optical cell of 1st embodiment of this invention A-A 'line sectional view in FIG. B-B 'line sectional view in FIG. Vertical section of a conventional optical cell Longitudinal sectional view of an optical cell according to a second embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Optical cell S ... Fluid to be measured 3 ... Hemoglobin concentration measuring device 11 ... Channel 2 ... Measurement light

Claims (6)

Intervening between a light source and a light receiving system for receiving measurement light emitted from the light source, wherein a light inlet for introducing the measurement light, a light outlet for deriving the measurement light, and a light inlet An optical cell comprising a single flow path for flowing a measurement target fluid that crosses the measurement light passing through the light exit port a plurality of times. The optical cell according to claim 1, wherein the flow paths have the same cross-sectional shape. The optical cell according to claim 1, wherein the flow path vertically crosses the measurement light. The optical cell according to claim 1, wherein the optical cell has a flat plate shape. 5. A measuring apparatus comprising: the optical cell according to claim 1; a light source for generating the light; and a light receiving system that receives the light that has passed through the optical cell. The measurement apparatus according to claim 5, wherein the measurement target is a liquid obtained by diluting blood.