JP3217852B2 - Photodetector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a substance by a luminescence method in a capillary electrophoresis method.

[0002]

2. Description of the Related Art Capillary electrophoresis is a general term for a detection method in which a sample is introduced into a thin tube and a voltage is applied to both ends for analysis. As this detection method, methods using fluorescence detection, electric conductivity detection, and the like, including an absorption method, have been reported. An absorption method is widely used in such a method for detecting a sample. In this method, an extremely small window for measurement is provided in a capillary, ultraviolet rays are irradiated, and the absorbance is measured. However, in order to improve the resolution, the length of the optical path to be measured must be shortened, so that there is a disadvantage that the signal obtained by the detector is reduced.

[0003] In other words, this drawback is that a signal with good S / N cannot be obtained unless the analytes (for example, proteins of the same molecular weight) are electrophoresed together to some extent.

[0004] Therefore, as one of the methods for increasing the detection sensitivity over the absorption method, a luminescence method in which an analyte is labeled with a luminescence reagent or the like and the luminescence is measured is promising.

[0005]

However, in the conventional absorption method, the light emitted from the capillary is scattered in all directions, and the light reaching the detector is a part of the amount of light emitted, so that it is necessary for detection. The light quantity could not be obtained.

Accordingly, an object of the present invention is to provide a photodetector capable of obtaining a required light amount when measuring by a light emission method.

[0007]

According to the present invention, there is provided a photodetector for applying an applied voltage to a buffer solution inside the capillary from both ends thereof and detecting light from a sample moving in the capillary by a potential difference. A photodetector group in which photodetectors are arranged in the same plane along the longitudinal direction of the capillary, and a bonding surface provided corresponding to each of the plurality of photodetectors is defined as a light transmitting surface, and the opposite inner surface is defined as a light transmitting surface. A light-transmitting material serving as a light-reflecting surface, comprising a light-collecting member in which a plurality of shielding layers intersecting the axis of the capillary are arranged at predetermined intervals, wherein the capillary penetrates the light-collecting member. I do. The surface opposite to the light transmitting surface is desirably a secondary paraboloid, an elliptic cylinder, or an elliptic cylinder made of a polyhedron. Further, the shielding layer may be a light reflecting surface toward the inside of the light collecting member. Further, it is desirable that the capillary penetrates the light-collecting member at a position separated by a predetermined distance from the bonding surface.

[0008]

According to the above arrangement, in the light-collecting member through which the capillary penetrates, the joint surface with the photodetector is a light transmitting surface,
The opposite surface of the joining surface is a light reflecting surface. For this reason, the light emitted from the sample moving in the capillary in the direction opposite to the bonding surface is reflected by the light reflecting surface, and reaches the photodetector together with the light emitted in the direction of the bonding surface. In addition, since the shielding layer exists between the adjacent light condensing members, light does not leak to another adjacent photodetector.

[0009] If the half surface of the light transmitting surface is a curved surface, the light radiated in four directions substantially perpendicular to the axis of the capillary is reflected by the light reflecting surface and reaches the photodetector. If the shielding layer is formed on the light reflecting surface toward the inside of the light collecting member, the light that has reached this surface is also reflected toward the photodetector. If the capillary penetrates the light-collecting member at a position separated by a predetermined distance from the bonding surface, even if the photodetector is cooled, it is difficult to transmit the influence of heat to the capillary.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIG. 1 is a conceptual diagram of a capillary electrophoresis apparatus using a photodetector according to a first embodiment. As shown in FIG. 1, the capillary electrophoresis apparatus includes a light detection device 1 having a capillary 2, a reservoir 10a containing a positive buffer, and a reservoir 10b containing a negative buffer. . Each reservoir 10a, 10
Each of the ends of the capillary 2 of the photodetector 1 is arranged at b. A positive electrode 11a is provided in the reservoir 10a containing the positive buffer, and a negative electrode 11b is provided in the reservoir 10b containing the negative buffer.
b is connected to the power supply 13. This power supply 13
Are controlled by the controller 12. The controller 12 also serves as an arithmetic processing device, is connected to each detector 2 of the photodetector 1, and also performs a process of calculating an output from the detector 2.

FIG. 2 is a perspective view of a light detecting device according to a first embodiment of the present invention, and FIG. 3 is a perspective view of a light collecting member provided in the light detecting device. As illustrated, the photodetector 1 includes a solid-state sensor (for example, a group of photodetectors in which a plurality of pixels (photodiodes) as a plurality of photodetectors 3 are juxtaposed along the longitudinal direction of the capillary 2. A photodiode array element). In this case, the pitch of each photodiode and the pitch of the plate 4 serving as a reflective condenser described later need to correspond one to one, but a linear image sensor having a large number of pixels is used. In this case, the pitch of the plurality of pixels may correspond to the pitch of the plate 4.
That is, when the width of the plate 4 is W and the pixel pitch of the linear image sensor is P, W = nP (n
Is a positive integer), and the resolution is as high as P (several tens of μm). Here, the linear image sensor may be of a charge transfer type (CCD type),
A switch type may be used.

The outputs of the plurality of photodetectors 3 are each supplied to an arithmetic processing unit (not shown in FIG. 2). Further, the light detection device 1 is provided with a plurality of plates 4 made of a light transmitting material provided corresponding to each of the plurality of light detectors 3. As shown in FIG. 3, the plurality of plates 4 are superimposed on each other via a shielding layer 7 (for example, a metal film) to form a light collecting member 5. Each plate 4 constituting the light condensing member 5 has a through hole 6
Are formed, and the capillary 2 penetrates the through hole 6 so that the axis of the capillary 2 and the shielding layer 7 intersect. The shielding layer 7 is a light reflecting surface toward the inside of the light collecting member 5.

Further, in each plate 4, a joint surface 8 with the photodetector is a flat surface, and a secondary paraboloid 9 is formed on a surface opposite to the joint surface 8. A refractive index matching agent is interposed between the bonding surface 8 and the photodetector 3, and a light transmitting surface treatment is performed on the bonding surface 8. The secondary paraboloid 9 is a light reflecting surface,
For example, a light reflection surface treatment is performed by a metal coating. The through-hole 6 provided in the side surface 15 of the plate 4 is located at a position that becomes a focal point in relation to the secondary paraboloid 9. The capillary 2 is a hollow wire-shaped member, is made of phased silica, and has an outer surface coated with a polyimide film to increase its bending strength.

Next, the operation of the first embodiment will be described. The sample you want to analyze (for example, DNA or protein)
Is mixed with a buffer having the same polarity. Therefore, the electrode 11 provided in each of the reservoirs 10a and 10b
If a voltage is applied to a and 11b by the power supply device 13, a potential difference is generated between both ends of the capillary 2, so that the sample moves in the capillary 2.

At this time, the condensing member 5 through which the capillary 2 penetrates has a joint surface 8 with the photodetector 3 as a light transmitting surface, and a secondary paraboloid 9 facing the light transmitting surface as a light reflecting surface. It is. For this reason, the light radiated in all directions from the sample moving in the capillary 2 is reflected by the secondary paraboloid 9, and
Reaches the photodetector 3 together with the light emitted in the direction of. In addition, since the light-shielding layer 7 formed on the light reflection surface is present between the adjacent light-collecting members 5 toward the inside of the light-collecting member 52, light may leak to another adjacent light detector 3. Not
The light is reflected toward the photodetector 3. Therefore, crosstalk can be reduced and the light collection efficiency can be improved.

Since the capillary 2 and the photodetector 3 are separated from each other at a constant interval, even when the photodetector 3 is cooled, the effect of heat is hardly transmitted to the capillary 2. Therefore, the photodetector 3 can be cooled without affecting the capillary 2 and the sensitivity of the photodetector 3 can be increased, so that thermal noise can be reduced and S / N can be improved.

The heat of the capillary 2 is not easily transmitted to the photodetector 3. For this reason, the thermal noise of the detector 2 decreases, and the S / N
The ratio can also be improved.

Next, a second embodiment of the present invention will be described. The second embodiment differs from the first embodiment in the shape of the plate 4. That is, in the light detection device 1 according to the second embodiment, the portion corresponding to the secondary paraboloid 9 of the plate 4 of the light detection device 1 according to the first embodiment is a plane passing through one focal point or near the focus. The difference is that the elliptical cylinder surface is missing. In a portion forming the elliptic cylinder surface, a light reflecting surface treatment is performed together with the side surface 15. Side 15
At one of the positions on the upper side that is the focal point in relation to the elliptical cylinder surface, a hole that allows the capillary 2 to penetrate is provided.
The fact that the capillary 2 penetrates this hole is the same as in the first embodiment. In addition, at or near the other focal point position, the bonding surface 8 is subjected to the same light transmission surface treatment as in the first embodiment. This plate 4
In the same manner as in the first embodiment, the photodetection device 1 is obtained by attaching a polymerized product to the detector group and penetrating the capillary 2.

Therefore, in the second embodiment, since such a configuration is adopted, the capillary 2 at one focus is used.
Is reflected by the elliptical cylindrical surface subjected to the light reflecting surface treatment and converges to the other focal point. Therefore, when the length of the light receiving element is not so long as in the case of an avalanche photodiode, the collection efficiency of photons is increased.

That is, in the case of the secondary paraboloid 9 as in the first embodiment, the reflected light becomes a parallel light as shown in FIG. When the length of the light receiving element such as a CCD or a MOS type linear image sensor is relatively long, light can be efficiently received. However, when the reflected light is parallel light, the photon collection efficiency is low when the length of the light receiving element is short.

Therefore, as in the second embodiment, a plate 4 including an elliptical cylindrical surface is formed, and a capillary 2 is formed at one focal point.
And the detector 2 is arranged near the other focal point. With this arrangement, the light emitted from one of the focal points will
As shown in (b), the light is reflected by the elliptical cylinder and converges to the other focal point. As a result, even when the length of the light receiving element is not too long, the collection efficiency of photons can be increased.

Note that even if the curved light reflecting surface in the plate 4 included in the plate 4 is a polyhedron close to an elliptical cylinder surface as shown in FIG. 5, light emitted from one focal point will be the other focal point. Converges to Therefore, the same effect as in the above embodiment can be obtained even if the light reflecting surface is not necessarily a smooth mirror surface. Further, in each of the above-described embodiments, the shielding layer 7 is formed as a light reflecting surface toward the inside of the light collecting member 5, but may be subjected to, for example, a black processing without forming the light reflecting surface. In this case, although the light-collecting efficiency is reduced, it is possible to reduce the crosstalk, which is the original purpose of the shielding layer 7.

[0024]

As described above in detail, according to the present invention, in the light-collecting member through which the capillary penetrates, the joining surface with the photodetector is a light transmitting surface, and the opposite surface of the joining surface is light. It is a reflective surface. For this reason, the light emitted from the sample moving in the capillary in the direction opposite to the bonding surface is reflected by the light reflecting surface, and reaches the photodetector together with the light emitted in the direction of the bonding surface. In addition, since the shielding layer exists between the adjacent light condensing members, light does not leak to another adjacent photodetector. Therefore, the photon collection efficiency can be improved.

Further, if the surface opposite to the light transmitting surface is formed into a curved surface, all the light radiated in four directions substantially perpendicular to the axis of the capillary is reflected by the light reflecting surface and reaches the photodetector. Thereby, the collection efficiency of photons can be further increased. If the shielding layer is formed on the light reflecting surface toward the inside of the light collecting member, the light that has reached this surface is also reflected toward the photodetector. For this reason, crosstalk between adjacent detectors can be reduced, and the collection efficiency of photons is further improved. Furthermore, since the capillary penetrates the light-collecting member at a position separated by a predetermined distance from the bonding surface,
Even if the photodetector is cooled, it is difficult to transmit the effect of heat to the capillary. Therefore, the photodetector can be cooled without affecting the capillary, so that the sensitivity of the photodetector can be increased, thermal noise can be reduced, and S / N can be improved.

As described above, by using the photodetector according to the present invention, it is possible to achieve high resolution and high sensitivity (high photon collection efficiency) required for measurement by the light emission method. .

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a capillary electrophoresis apparatus using a photodetector according to a first embodiment.

FIG. 2 is a perspective view of the photodetector according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a light collecting member provided in the photodetector according to the present invention.

FIG. 4 is a cross-sectional view of a photodetector according to a first embodiment and a second embodiment of the present invention.

FIG. 5 is a sectional view of a photodetector according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light detection device, 2 ... Capillary, 3 ... Detector, 4 ...
Plate, 5 ... Light collecting member.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor: Manabu Yasukawa 1126 Nomachi, Hamamatsu-shi, Shizuoka Prefecture Inside Hamamatsu Photonics Co., Ltd. (56) References JP-A-5-209832 (JP, A) JP-A-3-3 72247 (JP, A) JP-A-61-223538 (JP, A) JP-A-5-307003 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/00-21 / 74 JICST file (JOIS)

Claims (4)

(57) [Claims] 1. A photodetector that applies an applied voltage to a buffer solution inside both ends of a capillary and detects light from a sample moving in the capillary due to a potential difference, wherein a plurality of photodetectors are connected to the length of the capillary. A group of photodetectors arranged side by side on the same plane along the direction, and a light having a bonding surface provided corresponding to each of the plurality of photodetectors as a light transmitting surface and an inner surface on the opposite surface as a light reflecting surface. A light-collecting member comprising a transparent substance and having a plurality of shielding layers intersecting with the axis of the capillary arranged at predetermined intervals, wherein the capillary penetrates the light-collecting member. 2. The light detecting device according to claim 1, wherein the surface opposite to the light transmitting surface is any one of a secondary paraboloid, an elliptic cylinder, and an elliptic cylinder made of a polyhedron. 3. The photodetector according to claim 1, wherein the shielding layer is a light reflecting surface facing the inside of the light collecting member. 4. The photodetector according to claim 1, wherein the capillary penetrates the light-collecting member at a position separated by a predetermined distance from the bonding surface.