DE102013101888A1 - Device for optical analysis of test strip with substance for detection of analyte, has deflection unit reflecting light towards detector, where deflecting unit is arranged such that only light emitted by substance falls into detector - Google Patents

Abstract

The device (100) has a receiving unit (3) for receiving a test strip, and a light source (9) e.g. LED, for exciting a substance of the test strip. A detector (14) or CCD matrix, is arranged for detecting light emitted by the substance of the test strip, where the substance emits or reflects light when the substance enters into interaction with an analyte. A deflection unit i.e. mirror (11), is arranged for reflecting light emitted from the test strip towards the detector. The deflecting unit is arranged such that only light emitted by the substance of the test strip falls into the detector. An independent claim is also included for a method for optical analysis of a test strip with a substance for detection of an analyte.

Description

The invention relates to a device for optical, in particular photometric analysis of a test strip of a lateral flow assay, as well as the use of such a device.

The apparatus for optically analyzing a test strip having at least one substance for detecting an analyte, which substance emits or reflects light when it interacts with the analyte, comprises at least the following components: a receiving unit for receiving a test tire, at least one A light source for exciting the substance of the test strip, a detector for detecting the light emitted by the substance of the test strip and a deflection means for reflecting the light emitted by the test strip in the direction of the detector.

introduction

The operating principle of arrangements for the photometric evaluation and quantification of lateral flow assays (LFA) in the form of rapid strip tests is based on the fact that a biological fluid (such as blood, plasma, urine, etc.) is applied to the test strip and the reflection behavior of a defined section on the test strip changes, or after the optical excitation with an electromagnetic radiation emission takes place, whereby the degree of change of the reflection or the emission correlates with the concentration of a specific, sought analyzes in the sample.

A test strip used in the LFA comprises a test substrate mounted in a cassette having at least one opening for receiving biological fluid to be examined and having at least one opening in which a reaction (eg, color change) is detected can be. On the test substrate of the test strip, the sample liquid flows by capillary action on a strip of flow and encounters zones (eg lines or dots) which have been pretreated with an antibody or antigen and to which a binding to a marker ("label") is caused by a chemical reaction. ) he follows. These markers can, for. As gold colloids, fluorophores, latex or the like. You may experience a color change or cause the exposure of photo-luminescence when exposed to special color sources, the degree of color change or radiation with the concentration of the analyte to be detected correlates. This means that the evaluation of the reflection signal or the photo-luminescence radiation indicates the concentration of the analyte.

Such rapid tests are due to their easy-to-handle operating principle increasingly widespread use in many applications. The most exact possible quantification is becoming increasingly important.

Such tests are known z. B. as qualitative tests in pregnancy. Quantitative tests are now used in so-called point-of-care diagnostics (for example in the field of cardiac infarction and cancer diagnostics, or the detection of inflammatory markers), but also in the detection of drugs and allergies. Other fields of application include tests in the food industry (such as the investigation of cereals on mycotoxins), the examination of water samples for harmful substances and the detection of explosives.

There is currently a need for devices that are as robust and suitable for mobile use, as well as high resolution and accuracy.

An important trend in this case is that the test fields to be analyzed are designed as different lines or points to be detected, closely adjacent to each other, or into several strips that are arranged side by side for different analytes in a common cassette (eg in the case of allergies). diagnostics).

The dynamics of the color change plays a major role for an exact evaluation of the test tire. Since the analytes may contain solvents which must evaporate during test development, erroneous measurements may be made in evaluating the reflectance signal in the presence of liquid. On the other hand, the test result for a user should be easy to read without having to wait until a stable dry state has set.

In the devices for the photometric evaluation of LFAs, camera systems prove to be advantageous in which a two-dimensional CCD array is used as the detector, as a result of which the image is generated by a single operation. Thus, the image of the entire object to be analyzed is imaged by optics onto the CCD detector, which consists of an array of photosensitive photodiodes. The electronic information is transmitted to a microprocessor with a clock frequency of several 1000 pixels per second and processed. An advantage of these camera systems is the fast processing speed, so that processes can be virtually filmed. The disadvantage is that the object field to be imaged is limited by the magnification. In addition, a good image requires relatively large Lens systems and greater distances between object, lens and image.

From the DE 10 2008 058 132 A1 For example, a device for optical analysis of a test strip is known in which an optical imaging arrangement with a CCD chip is realized. The test strip to be analyzed is illuminated by a light source. The optical imaging takes place via a deflection mirror and through a lens. The receiver unit consists of a receiver PCB on which a CCD detector is mounted.

A disadvantage of this device is the limited field of view for imaging the test tire to be analyzed. The better the resolution should be, the smaller the object field to be imaged becomes. In particular, measurements for lateral flow assays with multiple adjacent strips (for example, as is common in allergy testing, with up to 12 strips for different allergens) are not possible with the system. In addition, it turns out that the resolution of this system is limited by back reflections or light scattering.

Accordingly, the problem underlying the invention was to provide a device of the type mentioned, which has a greater resolution.

Description of the invention

This problem is solved by a device according to claim 1.

If, in the optical arrangement of a device for optical analysis of a test strip, the light source is close to the path of the image, the light of the light source is reflected by additional in the beam path optical interfaces and reaches the CCD detector (sensor), so that the image of Test strip is falsified. This is avoided with the present invention.

Back reflections are caused by a light source with a relatively large emission angle, for example of 120 °. Their light can be partially reflected back by optically transparent interfaces between the camera and the sample. The same effect can be caused by liquid solvents on the test strip.

The device described above for the qualitative or quantitative optical, in particular photometric analysis of a test strip according to the invention has a deflection that is arranged such that only the light reflected from the substance of the test tire light can fall into the detector, but not other scattered light. Light that is not emitted from the direction of the substance of the test tire can not fall on the light detector.

Preferably, the light source and the deflection means are positioned so that substantially no or only a little direct light from the light source falls on the detector.

The invention provides an arrangement for the photometric evaluation of strip tests, which offers a maximum of flexibility with respect to excitation and detection of different wavelengths, enables rapid and spatially resolved quantification and at the same time allows the evaluation of large fields of view and multiple test strips arranged side by side on a test panel power. In addition, reflections from the light source (intrinsic reflections) are minimized in the device.

The light source and the deflecting means are arranged in the camera such that no or only a little direct light from the at least one light source reaches the detector. In particular, the light source is arranged in a region adjacent to the deflection.

The deflection means is preferably a mirror or a prism.

The detector is preferably a CCD sensor or CCD array (CCD chip), whereby the entire image of the object to be analyzed is recorded.

The beam path within the device is described in particular with reference to the drawings of 2 described in more detail below. In short, at least one light source of the device emits light in a defined emission angle. The opening angle of the light source with ≥ 120 ° is preferably dimensioned such that it is directed directly onto the object field of the test tire. Thus, an area of at least 20 mm by 30 mm can be imaged. The angle of the arrangement of the light sources and the opening angle are dimensioned such that the back reflections of boundary surfaces parallel to the object field can not reach the detector when the beam is deflected by the deflection means of the device. Only the deflected light contributing to the image then falls into the detector of the device and can be processed by software.

In accordance with the present invention, stray radiation that does not originate from the test tire to be analyzed may not fall on the detector.

For this purpose, the angle of the plane of the deflection with respect to the object plane is not equal to 45 °, and at the same time the position of the light source such that the reflections from the beam angle of the light source can not be imaged on the detector. This is supported by the design of the entire camera body so that no stray radiation from outside into the camera and thus on the detector can fall.

In a preferred embodiment of the device, a surface normal of the deflection means forms an acute angle of non-45 ° to a surface normal of the detector.

In a further preferred embodiment of the invention, a surface normal of the mirror to an area normal of the detector forms an angle of 45.5 ° to 55 °, preferably of 45.5 ° to 50 °, particularly preferably of 50 °.

The advantage of this arrangement is that the surfaces in the beam path must not be arranged inclined to the axis of the image and for imaging only lighting proportions can be used, which are diffused and not reflected directly from the test strip. For example, if there is a wet film (eg, a solvent) on the test strip that volatilizes during the course of the test development, it can not falsify the image and therefore the measurement because these direct reflections do not enter the detector.

In a preferred embodiment of the invention, the light source is at least one LED, at least one laser and / or at least one laser diode. In one embodiment of the device, a plurality of light sources are present, which are selectively controllable.

In a preferred embodiment of the invention, the device has at least one diaphragm, which is arranged in the beam path in front of the detector. The aperture can be arranged in a change magazine for selectively arranging diaphragms of different properties in the beam path. Then can be brought into the beam path for each measurement to be performed each optimal aperture.

Furthermore, in the imaging beam path, in one embodiment of the invention, a filter is arranged in a region as close as possible to the diaphragm. At this point, the beam of the image has its smallest cross-section. Therefore, a small filter can be used that completely covers the space between the illumination and the detector with a small opening.

The combination of excitation wavelength of the light source and selection of the filter is selectable. For example, the excitation can be effected by light sources having defined wavelengths which are suitable for exciting fluorescence radiation in the sample.

The filter is preferably designed as a bandpass filter or edge filter in such a way that, although it allows the fluorescence radiation to pass, it blocks all other wavelengths, in particular also the excitation wavelength. The band edges of such filters are strongly dependent on the angle of incidence. Since the filter is passed by low-aperture beams that deviate only slightly from the normal angle of incidence, commercially available filters with high edge acuity can be used.

At the same time, in one embodiment of the device, a plurality of filters can be arranged in a magazine so that an optional replacement of the filters can take place. This replacement can be realized for example by motor or by software-controlled mechanical tilting. Thus, the system is flexible in terms of excitation and fluorescence wavelength and adaptable to a variety of applications and also able to evaluate several different fluorescent dyes sequentially and independently.

To stabilize the measurement conditions, a cooling system, in particular a Peltier element for cooling the detector is arranged in a preferred embodiment of the invention, which keeps the temperature of the detector constant, which is particularly advantageous for the reliable evaluation of fluorescence signals.

The device is also advantageous if test strips are to be measured which are not detectable by the given spatially limited object field.

If the device is to be suitable for analyzing a test strip with several adjacent test areas, the device preferably has a motor (traversing unit) for moving a test strip with several fields to be analyzed, so that each field located on the test strip can be measured separately.

If a test cassette with several test strips contained therein is to be measured, an analogous procedure can be followed. Thus, in one embodiment of the device, the evaluation area is extended by making a test cassette movable relative to the camera. The test cassette is then connected to a motorized unit passing through a Device electronics controlled, defined in the imaging plane moves. The test strips are moved one after the other into the object field of the camera to be imaged. The test fields can be recorded one after the other, electronically processed and analyzed.

An advantage of the image obtained by means of the device is that, based on the radiation of the analyte, two-dimensional images with spatial resolution are generated, in which the pixel height, represented in 3D form (as in FIG WO 2012/054645 A2 explained), the intensity of the color change or the fluorescence is visualized. It offers the user a variety of possibilities for quantification, especially with known software.

In a further aspect, the invention relates to the use of a device of the type described here for the qualitative or quantitative optical, in particular photometric or fluorescence analysis of a test strip with at least one substance for detecting an analyte, wherein the substance emits or reflects light when combined with the Analyte interacts.

With regard to a further aspect, the invention also relates to a method for qualitative or quantitative optical, in particular photometric, analysis of a test strip with at least one substance for detecting an analyte, wherein the substance emits or reflects light when it interacts with the analyte, the method is performed by means of a device of the type described here.

LIST OF REFERENCE NUMBERS

100, 100 '

contraption

1

test Device

2

adapter

3

Recording unit, receiving shaft

4a

first lateral guidance

4b

second lateral guidance

5

window opening

6

test areas

7

optically transparent pane

8th

level

9

light source

10

casing

11

Deflection means in the form of a mirror

12

cover

13

lens

14

Detector (sensor) in the form of a CCD matrix

15

filter

16

Coolant in the form of a Peltier element

17

cassette adapter

18

engine

19

spindle

characters

Show it:

1 : the arrangement according to the invention for the photometric analysis of a test strip;

2 : the beam path and the function of the device (camera);

3 : the design of the measuring device for fluorescence-based tests;

4 a preferred embodiment of the device with multiple filters; and

5 A preferred embodiment of the device for a test cassette in which a plurality of test strips are arranged side by side.

1 shows the arrangement according to the invention 100 for the photometric analysis of a test strip.

A test cassette 1 is located in an adapter 2 into a reception shaft 3 the device 100 is pushed to perform the analysis. To insert the test cassette 1 serve a first lateral guidance 4a and a second lateral guide 4b , The receiving shaft 3 and the adapter 2 have openings to the bottom, so that for example one on the back of the test cassette 1 applied barcode is visible and readable from below.

The test cassette 1 has a window opening 5 through which the test strips of the test cassette pass 1 are optically accessible from the top. There are test areas on the test strip 6 , z. B. Test lines to be optically analyzed.

Above the receiving shaft 3 there is a camera assembly with a detector 14 whose function is the color or radiation intensity of these test lines 6 to measure photometrically. The camera assembly goes down with an optically transparent lens 7 completed. Camera assembly and receiving shaft 3 can each other in one plane 8th to be adjusted.

The test strip with the test lines 6 comes with a light source 9 For example, LEDs on a circuit board that are attached to a housing 10 with an opening is mounted, lit. The test line 6 reflects a portion of the light, which via a deflection, here in the form of a mirror 11 in the case 10 is mounted on stop surfaces, is deflected. The light first radiates through an aperture 12 and then by a lens 13 to the image on the detector in the form of a CCD matrix 14 focused.

Based on 2 become the beam path and the function of the camera as a detector 14 the device 100 explained in more detail.

The at least one light source 9 emits light in a defined beam angle. The opening angle of the light source 9 is dimensioned so that it is preferably directed directly to the object field. The angle of the arrangement of the light source (s) and the opening angle are dimensioned so that the return reflections of interfaces, parallel to the object field (cutting disc, cover of the test, etc.) can not reach the CCD sensor.

In the 2 the outermost ray is shown by the light source 9 on the interface 7 passes, and like this through the interface 7 and the mirror 11 is reflected. This beam can not reach the detector 14 reach. To achieve this, according to the invention, the light source 9 close to the mirror 11 arranged and the mirror 11 is tilted by 5 ° so that the surface normal of the mirror 11 (perpendicular to the mirror) to the surface normal of the detector 14 instead of 45 ° has an angle of preferably 50 °. Thus, it is accepted that the object plane of the figure is also tilted by 5 °.

The advantage of the arrangement is that only light components that are diffuse and not directly reflected by the test strip can be used for imaging. For example, it is on the test strip of the test cassette 1 a wet film, z. As a liquid that is still volatilized in the course of the test development, this can not distort the image and thus the measurement, because these direct reflections do not get into the sensor.

3 shows the design of the measuring arrangement for tests based on fluorescence.

In fluorescence analysis, it is important to ensure a particularly high optical isolation between the excitation wavelength and the emission wavelength, since the excitation intensity can be several orders of magnitude greater than that of the emitted wavelength. Therefore, in this embodiment, the device 100 the arrangement of a filter 15 prefers.

In this case, it is advantageous to excite the test strip to be measured as needed LEDs or laser with the corresponding required excitation wavelength as a light source 9 to use. According to the invention is in the beam path near the aperture a filter 15 arranged, which separates the excitation radiation from the emission radiation. The advantage of this arrangement is that the beam cross-section of the image is particularly small at this point. Since the filter price depends directly on the area, this solution is cost-effective. In addition, by the arrangement of the filter 15 close to the aperture a very good separation between excitation wavelength and emission wavelength can be achieved.

The filter 15 is further irradiated almost vertically by the selected imaging ratio. In the commonly used high quality filters, a particularly good insulation is achieved when the filters 15 be irradiated as vertically as possible.

To stabilize the sensor temperature during the measurement is in the illustrated embodiment of the device 100 a Peltier element 16 for cooling the CCD detector 14 integrated.

There are applications where multiple excitation wavelengths and emission wavelengths are used. In this case, several parallel juxtaposed light sources can be used for illumination 9 can be used, which are selectively controlled. In this case, the filters must also 15 change. In the corresponding embodiment, it is advantageous to have multiple filters 15 near the aperture 12 with a change magazine to arrange and as needed in the beam path to move (arrow). For this purpose, a rotatable insert can be used, or a device with which the filters 15 folded or moved. This in 4 shown schematically.

Another embodiment of the device 100 ' is in 5 shown in the case of a test cassette 1 several test strips are arranged side by side. Here, the receiving shaft according to the invention to the camera assembly comprising the detector 14 movably arranged and is by means of a motor 18 controlled.

The cassette adapter 17 to hold one or more test cartridges 1 is moved in one direction on a slide, with a motor 18 and a spindle 19 is driven. Thus, the test fields to be measured are successively positioned so as to be successively in the light source 9 outgoing beam path can be brought.

Above the cassette adapter 17 is the camera (detector 14 ), whose function is related to the explanation of the 1 is described. With the engine 18 become the fields of vision of the test strips 1 one after the other into the object plane of the camera 14 moved and then the pictures taken and evaluated.

The advantage of this arrangement is that it makes the high resolution and advantages of a photometric evaluation by a camera usable for the evaluation of large-area cassettes with multiple test fields. Since a high resolution in cameras limits the size of the object fields, the evaluation of large-area cassettes is only possible because several fields are evaluated photometrically one after the other, which is why a motor feed can be arranged.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008058132 A1 [0011]
• WO 2012/054645 A2 [0039]

Claims (12)

Contraption ( 100 . 100 ' ) for optically analyzing a test strip having at least one substance for detecting an analyte, wherein the substance emits or reflects light when it interacts with the analyte, comprising - a recording unit ( 3 ) for receiving a test tire, - a light source ( 9 ) for excitation of the substance of the test strip, - a detector ( 14 ) for detecting the light emitted by the substance of the test strip and - a deflection means ( 11 ) for reflecting the light emitted by the test strip in the direction of the detector, characterized in that the deflection means ( 11 ) is arranged such that only the light emitted by the substance of the test tire can fall into the detector. Device according to claim 1, characterized in that the light source ( 9 ) and the deflection means ( 11 ) are positioned so that substantially no light from the light source ( 9 ) falls on the detector. Apparatus according to claim 1 or 2, characterized in that a surface normal of the deflection means ( 11 ) to a surface normal of the detector ( 14 ) forms an angle of not equal to 45 °, in particular greater than 45 °. Apparatus according to claim 1 to 3, characterized in that a surface normal of the deflection means ( 11 ) to a surface normal of the detector ( 14 ) forms an angle of 45.5 ° to 50 °, preferably of 50 °. Apparatus according to claim 1 to 4, characterized in that the light source ( 9 ) in a deflecting means ( 11 ) adjacent area is arranged. Apparatus according to claim 1 to 5, characterized in that the light source ( 9 ) has an LED, a laser and / or a laser diode. Apparatus according to claim 1 to 6, characterized in that the device at least one aperture ( 12 ), which is arranged in the beam path. Apparatus according to claim 1 to 7, characterized in that in one of the diaphragm ( 12 ) adjacent area a filter ( 15 ) is arranged to separate the excitation radiation from the emission radiation in the beam path. Apparatus according to claim 8, characterized in that the filter ( 15 ) is arranged in a changing magazine for selectively arranging filters of different properties in the beam path. Apparatus according to claim 1 to 9, characterized in that the device is a motor ( 18 ) for moving a test tire having a plurality of fields to be analyzed. Use of a device ( 100 . 100 ' ) according to claim 1 to 10 for the optical analysis of a test strip with at least one substance for the detection of an analyte, wherein the substance emits or reflects light when it interacts with the analyte. A method of optically analyzing a test strip with at least one substance for detecting an analyte, wherein the substance emits or reflects light when it interacts with the analyte, the method being performed by means of a device ( 100 . 100 ' ) is carried out according to claim 1 to 10.

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