TEST STRIP FIXATION DEVICE FOR OPTICAL MEASUREMENTS OF AN ANALYTE

Abstract

A test strip fixation device for use in a method of determining analyte concentration in a body fluid using a mobile device with a camera. The device has top and bottom surfaces, has an essentially planar shape, and also has a cut-out portion configured for application of a body fluid sample. The top surface has color reference fields with known reference color values, including grey and non-grey reference fields. The grey reference fields are symmetrically arranged around the cut-out portion and around at least some of the non-grey color reference fields. The top surface also has position detection code elements. The bottom surface has a connector configured for detachable connection of an optical test strip relative to the test strip fixation device, and a reagent test region of the test strip can be aligned with the cut-out portion. A method of using the device is also disclosed.

Claims

1. A test strip fixation device for use in a method for determining concentration of an analyte in a body fluid using a mobile device with a camera, said test strip fixation device comprising: a) a top surface and a bottom surface and having an essentially planar shape; b) a cut-out portion configured for application of a body fluid sample; c) the top surface comprising a plurality of color reference fields having known reference color values, including grey and non-grey reference fields, wherein the grey reference fields are symmetrically arranged around the cut-out portion and around at least some of the non-grey color reference fields, the top surface further comprising position detection code elements; and d) the bottom surface comprising a connector configured for detachable connection of an optical test strip to the test strip fixation device and for alignment of a reagent test region of the test strip with the cut-out portion.

2. The test strip fixation device according to claim 1, wherein: the test strip fixation device comprises first and second pairs of outer edges arranged essentially parallel to one another; and the test strip fixation device has an essentially rectangular or trapezoid shape and the outer edges of the first pair are longer than the outer edges of the second pair.

3. The test strip fixation device according to claim 2, wherein: the cut-out portion is located away from the first and second pairs of outer edges; and/or the cut-out portion is located in a central area of the test strip fixation device relative to the first and second pair of outer edges; and/or the cut-out portion is located away from a geometric center defined by the first and second pair of outer edges of the test strip fixation device.

4. The test strip fixation device according to claim 1, wherein: the test strip fixation device has a height of no more than 10 mm, including the top surface, the bottom surface and the connector; and/or the bottom surface is, at least in part, beveled from at least one of the outer edges towards a central region of the test strip fixation device, a central region of the test strip fixation device provides a maximum height of the test strip fixation device, and the central region has a planar surface.

5. The test strip fixation device according to claim 1, wherein a planar surface of a central region of the test strip fixation device deviates from a parallel orientation relative to the top surface by an angle of from 5° to 25°.

6. The test strip fixation device according to claim 1, wherein: at least some of the position detection code elements are located essentially at the outer edges of the test strip fixation device; and/or wherein at least some of the position detection code elements are located such that they delimit the grey reference fields on the top surface.

7. The test strip fixation device according to claim 1, wherein: the position detection code elements comprise ArUco markers; and/or the position detection code elements comprise information specific to the test strip fixation device, said information comprising at least lot-specific information and/or calibration information relating to the color reference fields.

8. The test strip fixation device according to claim 1, wherein the grey reference fields comprise at least three different grey shades arranged locally around the cut-out portion and/or around at least some of the non-grey color reference fields.

9. The test strip fixation device according to claim 1, wherein the connector comprises one or more guides.

10. The test strip fixation device according to claim 1, wherein the top surface and the bottom surface, including the connector, are formed as a one-piece injection molded part, wherein the color reference fields and the position detection code elements are applied to the top surface by a printing process, or wherein the color reference fields and the position detection code elements are printed onto a label which is applied to the top surface.

11. The test strip fixation device according to claim 1, further comprising the optical test strip which is adapted to be detachably connected to the connector, said optical test strip comprising a carrier and a reagent test region for application of the sample of body fluid, said reagent test region being arranged on said carrier and said carrier having a transparent zone or a cut-out zone at the location of said reagent test region.

12. The test strip fixation device according to claim 11, wherein the cut-out portion of the test strip fixation device has a size no smaller than the reagent test region.

13. The test strip fixation device according to claim 12, wherein the cut-out portion has a size which, when the optical test strip is connected to the connector, allows observation of a part of the carrier which is adjacent to the reagent test region.

14. The test strip fixation device according to claim 11, wherein: the test strip fixation device comprises first and second pairs of outer edges arranged essentially parallel to one another; the connector is arranged essentially perpendicularly relative to at least one of the outer edges of the first or second pair of outer edges; and the optical test strip when connected to connector extends at least 5 mm beyond said one of the outer edges.

15. A method for determining concentration of an analyte in a body fluid by using a mobile device having a camera, said method comprising: (i) providing an optical test strip having a carrier and a reagent test region arranged on the carrier, wherein the carrier has a transparent zone or a cut-out zone at the location of the reagent test region; (ii) providing a test strip fixation device having a top surface and a bottom surface and a cut-out portion, the top surface having a plurality of color reference fields having known reference color values, including grey and non-grey reference fields; (iii) detachably connecting the optical test strip to the test strip fixation device such that a sample application site of the reagent test region faces away from the bottom surface of the test strip fixation device; (iv) applying a sample of the body fluid to the reagent test region and thereby forming a color in the reagent test region, wherein the color is observable from the top surface through the cut-out portion and through the transparent zone or through the cut-out zone of the carrier of the optical test strip; (v) capturing by the camera an image containing at least a part of the optical test strip and at least a part of the top surface of the test strip fixation device, wherein the image comprises at least a part of the reagent test region having the sample of the body fluid applied thereto and further comprises at least a part of the color reference fields, including at least a part of the grey reference fields; and (vi) determining the concentration of the analyte from the color formed in the reagent test region upon application of the sample of the body fluid, taking into account at least some of the color reference fields, including the grey reference fields.

16. The method of claim 15, wherein the determining the concentration of the analyte in step (vi) further comprises taking into account local intensity variations in the image captured in step (v), wherein said local intensity variations may occur at the locations of one or more of the color reference fields, and wherein the grey reference fields are used to account for said local intensity variations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0080] FIG. 1 shows a schematic view of a bottom surface of an exemplary embodiment of a test strip fixation device;

[0081] FIG. 2 shows a schematic side view of the embodiment of the test strip fixation device of FIG. 1;

[0082] FIG. 3 shows a schematic view of the top surface of an exemplary embodiment of a test strip fixation device;

[0083] FIG. 4 shows a schematic view of a mobile device and an embodiment of a kit comprising a test strip fixation device and an optical test strip, in a perspective view; and

[0084] FIG. 5 shows a flow chart of an embodiment of a method for determining the concentration of at least one analyte in a body fluid.

DESCRIPTION

[0085] The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.

[0086] In FIGS. 1 and 2, respectively, an exemplary embodiment of a test strip fixation device is illustrated. FIG. 1 shows the bottom surface (104) of the test strip fixation device of this embodiment, whereas FIG. 2 provides a side view thereof. Overall, the test strip fixation device comprises an essentially planar shape, such that the height of the test strip fixation device is much less than the length and the width of its bottom surface (104) and its top surface (110). Particularly, the test strip fixation device has a rectangular shape, limited by its outer edges (108) and its corners (124), wherein two of the outer edges (108) form a first pair of outer edges, and the other two of the outer edges (108) form a second pair of outer edges, such that the outer edges (108) of each of said pairs are arranged parallel to one another.

[0087] Generally, the test strip fixation device may have a height of up to, and no more than 10 mm, including the top surface (110), the bottom surface (104) and the fixation element. In the embodiment shown, a central region (160) of the bottom surface of the test strip fixation device provides a maximum height of the test strip fixation device. Additionally, the bottom surface (104) may, at least in part, be beveled from at least one of the outer edges (108), e.g., from 2, 3 or 4 of the outer edges (108), towards the central region (160) of the bottom surface of the test strip fixation device. In this embodiment, the bottom surface (104) is, at least in part, beveled from all 4 of the outer edges (108) towards the central region (160) of the test strip fixation device, as is depicted in FIGS. 1 and 2 by the lines indicating the beveled parts (104a) of the bottom surface (104). Particularly, the central region (160) has a planar surface which is essentially parallel to the top surface (110) of the test strip fixation device. As the skilled person will readily appreciate, the beveled parts (104a) of the bottom surface (104) may be designed in the form of a continuously beveled area, i.e., without the miniature steps (104a) as depicted in FIGS. 1 and 2, respectively.

[0088] Referring again to FIGS. 1 and 2, respectively, a cut-out portion (116) is provided which is located away from the outer edges (108) of the test strip fixation device. Furthermore, the cut-out portion (116) is located in a central area of the test strip fixation device relative to the first and second pair of outer edges (108), particularly in a central area which at least in part overlaps with the central region (160). Additionally, in this embodiment, the cut-out portion (116) is located away from a geometric center defined by the first and second pair of outer edges of the test strip fixation device; in other words, if two straight lines are drawn from each of two of the corners (124) of the bottom surface (104) of the test strip fixation device, wherein said each two of the corners (124) are diagonally opposing each other, then the intersection of these two straight lines represents such an aforementioned geometric center; and the cut-out portion (116) is located away from said geometric center.

[0089] In the embodiment shown in FIGS. 1 and 2, respectively, the cut-out portion (116) has a circular shape. Furthermore, the cut-out portion (116) comprises a beveled part (116a). Thereby, the area of the cut-out portion (116) located in the top surface (110) of the test strip fixation device is enlarged to some extent towards the bottom surface. The cavity thus formed, with the cut-out portion (116) at the center of said cavity, facilitates precise application of the sample of body fluid to a reagent test field of an optical test strip to be used together with the test strip fixation device.

[0090] The bottom surface (104) comprises a fixation element (also referred to herein as a “connector”) for detachable connection of an optical test strip (not depicted in FIGS. 1 and 2) relative to said test strip fixation device. In this embodiment, the connector is arranged perpendicularly relative to the outer edges of one of the pairs of outer edges. In this arrangement, the optical test strip is to be connected to the test strip fixation device by inserting the optical test strip in the direction indicated by the arrow A in FIG. 1.

[0091] The connector may comprise one or more guiding elements (170, 172, 174) (also referred to as “guides”). In the embodiment shown, the connector comprises at least three guiding elements, specifically including a guide channel (170), an orifice (172), and an engagement hook (174). The guiding elements (170, 172, 174) together ensure proper positioning of the optical test strip (118) relative to the test strip fixation device. Particularly, the guide channel (170) is essentially U-shaped and serves to accommodate the optical test strip (118) when it is connected to the test strip fixation device, and is configured to guide the optical test strip (118) during insertion of the test strip into the guide channel (170). The orifice (172), which the optical test strip (118) is pushed through during insertion of the test strip into the guide channel (170), is configured to keep the test strip in place, specifically if the test strip fixation device is turned upside down or is otherwise turned around. Additionally, the engagement hook (174) is configured to securely fasten the optical test strip (118) to the test strip fixation device, as soon as a corresponding hole in said optical test strip (118) is aligned with the engagement hook (174), such that the test strip can be locked in place.

[0092] An optical test strip (118) to be used together with the test strip fixation device is adapted to be detachably connected to said test strip fixation device. Such an optical test strip (118) usually will comprise a carrier and a reagent test region (120) for application of the sample of body fluid. Said reagent test region (120) may be arranged on said carrier. Specifically, said carrier may have a transparent zone or a cut-out zone at the location of said reagent test region (120).

[0093] If an optical test strip (118), such as one as described herein above, is connected to the test strip fixation device, said optical test strip (118) usually will extend at least 5 mm beyond one of the outer edges (108), e.g., beyond the lower one of the outer edges (108) depicted in FIG. 1. Thereby, a robust and convenient user handling of the test strip fixation device and the optical test strip can be achieved.

[0094] Moreover, if the optical test strip (118) is connected to the test strip fixation device, the reagent test region (120) of the optical test strip (118) can be aligned with the cut-out portion (116) of the test strip fixation device. Generally, the cut-out portion (116) of the test strip fixation device has a size no smaller than the reagent test region (120) of an optical test strip (118) to be used together with the test strip fixation device. Specifically, the cut-out portion (116) has a size which, if the optical test strip (118) is connected to the fixation element (170, 172, 174) of the test strip fixation device, allows observation of at least a part of the carrier of the optical test strip (118), for example, a part of the carrier which is adjacent to the reagent test region (120).

[0095] Referring to FIG. 3, the test strip fixation device comprises a top surface (110) comprising a plurality of color reference fields (112, 114, 148, 150, 152, 154) having known reference color values. The color reference fields include grey reference fields (114, 150) which are locally, and in this embodiment symmetrically, arranged around the cut-out portion (116) and around the non-grey color reference fields (112, 148, 152, 154).

[0096] Generally, the color reference fields (112, 114, 148, 150, 152, 154) may be distributed equally over the top surface (110), specifically in such a way that the plurality of color reference fields (112, 114, 148, 150, 152, 154) may be distributed over the entire top surface (110). As an example, the color reference fields (112, 114, 148, 150, 152, 154) may be arranged in a matrix pattern, such as a rectangular matrix pattern. However, the color reference fields (112, 114, 148, 150, 152, 154) may also be arranged in other ways, such as separately from each other. In the embodiment shown, the top surface (110) comprises a plurality of gray color reference fields (114, 150) surrounding the non-grey color reference fields (112, 148, 152, 154). The non-grey color reference fields (112, 148, 152, 154) and the gray color reference fields (114, 150) may not overlap each other.

[0097] In FIG. 3, the grey reference fields (114, 150) comprise more than three different grey shades. Specifically, the grey reference fields (114, 150) comprising the different grey shades are arranged locally around the cut-out portion. Additionally, the grey reference fields (114, 150) comprising the different grey shades are arranged locally around at least some of the non-grey color reference fields (112, 148, 152, 154).

[0098] Furthermore, top surface (110) comprises position detection code elements (122). In this embodiment, the position detection code elements (122) are located essentially at the outer edges (108) of the test strip fixation device. Additionally, and as an alternative to the embodiment shown, the position detection code elements (122) may be located on the top surface (110) such that they delimit the color reference fields (112, 114, 148, 150, 152, 154), specifically including the grey reference fields (114, 150), on the top surface (110).

[0099] The position detection code elements (122) may be or may, as an example, comprise at least one of a position marker, such as an ArUco code, a barcode, a QR-code, a label or a combination thereof. Specifically, the position detection code elements (122) may comprise one or more ArUco codes, such as in the corners of a rectangular matrix comprising the color reference fields (112, 114, 148, 150, 152, 154). Thus, generally, the position detection code elements (122) may be arranged in at least one corner (124) of the top surface (110). For example, at least one position detection code element (122) may be arranged in each of the corners (124) of the top surface (110), specifically in such a way that the position detection code elements (122) may be visible together with the plurality of color reference fields (112, 114, 148, 150, 152, 154).

[0100] The position detection code elements (122) used here comprise squared markers, and particularly ArUco markers. Furthermore, the position detection code elements (122) may comprise information specific to the test strip fixation device, said information comprising, for example, lot-specific information and/or calibration information relating to the color reference fields (112, 114, 148, 150, 152, 154). Further, the position detection code elements (122) may comprise information about the orientation of the top surface (110) of the test strip fixation device.

[0101] The top surface (110) and the bottom surface (104) including the fixation element may efficiently be formed as a one-piece injection molded part. The color reference fields (112, 114, 148, 150, 152, 154) and the position detection code elements (122) may be applied to the top surface (110) by a printing process. Alternatively, the color reference fields (112, 114, 148, 150, 152, 154) and the position detection code elements (122) may be printed onto a label which is applied to the top surface, e.g., by use of an adhesive, an adhesive tape, or the like. In an exemplary embodiment, the color reference fields (112, 114, 148, 150, 152, 154), including the gray color reference fields (114, 150), may be printed on a pre-printed gray-colored background of the top surface (110). Thus, the color reference fields (112, 114, 148, 150, 152, 154) may overlap with the gray-colored background of the top surface (110).

[0102] In FIGS. 3 and 4, respectively, the top surface (110) comprises a cut-out portion (116) of a rectangular shape. Thus, an optical test strip (118) or at least a part thereof may be visible through the cut-out portion (116) if the optical test strip (118) is connected to the test strip fixation device, as is the case with regard to FIGS. 3 and 4. Specifically, a reagent test region (120) of the optical test strip (118) may be visible through the cut-out portion (116).

[0103] In FIG. 4, a schematic view of a mobile device and an exemplary embodiment of a kit comprising a test strip fixation device and an optical test strip to be used therewith, in a perspective view. The kit comprises at least one test strip fixation device and at least one optical test strip (118). Further, the kit may comprise at least one mobile device (128). The mobile device (128) may be, or may comprise, at least one of a cell phone, a smartphone, a tablet computer or the like. Further, the mobile device (128) has at least one camera (130). The camera (130) of the mobile device (128) may be configured for recording images (herein also referred to as “capturing images”), specifically color images. Thus, the camera (130) may be a color camera, and may comprise at least three color sensors, such as at least one color sensor for the R, G, B colors.

[0104] Further, the mobile device (128) generally comprises at least one processor (132). The processor (132) may be configured, specifically by software programming, to perform one or more of the method steps of the method for determining the concentration of an analyte in a body fluid according to this disclosure. An exemplary embodiment of said method is shown in FIG. 5, and will be described in further detail below.

[0105] The processor (132) may specifically be configured for supporting the capturing of at least one image of the top surface (110) of the test strip fixation device. Specifically, the processor (132) may prompt a user of the mobile device (128) to capture the image. Additionally or alternatively, the processor (132) may be configured for automatically capturing the image of the top surface (110), specifically when the top surface (110) may be in a field of view.

[0106] The top surface (110) specifically may be embodied according to any one of the embodiments disclosed in connection with FIG. 3 as described in further detail above. The top surface (110) comprises the plurality of color reference fields (112, 114, 148, 150, 152, 154) having known reference color values. Further, the test strip fixation device comprises the at least one cut-out portion (116). Thus, the optical test strip (118) may be visible through the cut-out portion (116), specifically if the optical test strip (118) is connected to the test strip fixation device, such that both, the top surface (110) and the optical test strip (118), may be visible on the at least one image captured by the camera (130) of the mobile device (128). Specifically, the at least one reagent test region (120) of the optical test strip (118) may be visible through the cut-out portion (116), more specifically if looking from the direction of the top surface (110). In such an arrangement, the sample of body fluid is to be applied to the reagent test region (120) of the optical test strip (118) from the direction of the bottom surface. The color formed in the reagent test region (120) is then visible through the cut-out portion (116). Additionally or alternatively, the sample of body fluid may be applied to the optical test strip before it is connected to the test strip fixation device. Furthermore, additionally or alternatively, an optical test strip having a capillary for receiving the sample of body fluid and/or for transporting the sample of body fluid to the reagent test region (120) may be used together with the test strip fixation device.

[0107] The top surface (110) further comprises the at least one position detection code element (122). The position detection code elements (122) are arranged on the top surface (110) such that the position detection code elements (122) may be detectable by the camera (130) of the mobile device (128). The at least one position detection code element (122) may be used for identifying the orientation of the test strip fixation device and of the top surface (110) thereof, relative to the camera of the mobile device. Specifically, the processor (132) of the mobile device (128) may be configured for detecting the position detection code elements (122) on an image captured by the camera (130) and for further retrieving information about the orientation of the top surface (110).

[0108] In FIG. 5, a flow chart of an exemplary embodiment of a method for determining the concentration of at least one analyte in a body fluid is shown. The method comprises using at least one mobile device (128) having at least one camera (130). The method further comprises using at least one optical test strip (118) and the test strip fixation device as described herein above.

[0109] The method comprises the following steps, which specifically may be performed in the given order. Still, a different order may also be possible. It may be possible to perform two or more of the method steps fully or partially simultaneously. It may further be possible to perform one, more than one or even all of the method steps once or repeatedly. The method may comprise additional method steps that are not listed.

[0110] The method comprises: [0111] (i) (denoted with reference number 210) providing the optical test strip (118), wherein said optical test strip (118) comprises a carrier and a reagent test region (120) being arranged on said carrier, wherein said carrier comprises a cut-out zone (or, alternatively, a transparent zone) at the location of said reagent test region (120); [0112] (ii) (denoted with reference number 220) detachably connecting said optical test strip (118) to the test strip fixation device; specifically such that a sample application site of the reagent test region (118) faces away from the bottom surface (104) of the test strip fixation device; [0113] (iii) (denoted with reference number 230) applying a sample of the body fluid to said reagent test region (120), whereby a color is formed in the reagent test region (120), which color can be observed from the direction of the top surface (110) through the cut-out portion (116) of the test strip fixation device and through the cut-out zone (or, alternatively, the transparent zone) of the carrier of the optical test strip (118); [0114] (iv) (denoted with reference number 240) capturing by the camera (130) at least one image containing at least a part of the optical test strip (118) and at least a part of the top surface (110) of the test strip fixation device, wherein the image comprises at least a part of the reagent test region (120) having the sample of the body fluid applied thereto, wherein the image further comprises at least a part of the color reference fields, including at least a part of the grey reference fields; and [0115] (v) (denoted with reference number 250) determining the concentration of the analyte from the color formed in the reagent test region (120) upon application of the sample of the body fluid, taking into account at least some of the color reference fields, including the grey reference fields.

[0116] In step (iv), the capturing of the image of the reagent test region (120) may be performed by the processor (132), for example, by prompting the user to capture the image and/or by automatically capturing the image.

[0117] Further, the method may comprise an analytical measurement which comprises detecting a color value of the reagent test region (120) having the sample of the body fluid applied thereto and determining the analyte concentration based on the color formation reaction of the reagent test region (120). To this end, the method may further comprise determining measured reference color values for at least some of the color reference fields (112, 114, 148, 150, 152, 154), from the image; and determining a relationship between at least some of the measured reference color values and the corresponding known reference color values. Thereby, the relationship determined may be used to correct measured color values of the color formation reaction, in particular by using a color transformation matrix. The analyte concentration may be determined by using the corrected color values.

[0118] The method for determining the concentration of an analyte in a body fluid may at least partially be computer implemented, specifically steps (iv) and (v) of the method. The mobile device (128) may specifically be configured for executing the computer program, which when executed by the mobile device (128), cause the processor (132) of the mobile device (128) to perform steps (iv) and (v) of the method. The processor (132) may specifically be configured for capturing the at least one image of the reagent test region (120), such as by prompting the user to capture the at least one image and/or by automatically capturing the at least one image.

[0119] Further, the processor (132) may be configured, specifically by software programming, for determining the analyte concentration based on the color formation reaction of the reagent test region (120). The processor (132) may be configured for determining the analyte concentration by evaluating the captured image, deriving a change of one or more color coordinates, or any linear or non-linear combination thereof, taking place during the color formation reaction and transforming the change of the at least one color coordinate into the analyte concentration value. Specifically, the processor (132) may be configured for using a relationship between at least some of the measured reference color values and the corresponding known reference color values, for deriving a true color value from the captured image. Thus, the processor (132) may correct the measured color values of the captured image by transforming measured color values into true color values using a color transformation matrix determined from the relationship described herein above.

[0120] Specifically, the determining the concentration of the analyte in step (v) further may comprise taking into account local intensity variations in the at least one image captured in step (iv), wherein said local intensity variations may occur at the locations of one or more of the color reference fields, and wherein the grey reference fields are used to account for said local intensity variations.

[0121] While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

LIST OF REFERENCE NUMBERS

[0122] 104 bottom surface [0123] 104a beveled part of bottom surface [0124] 108 outer edge [0125] 110 top surface [0126] 112 color reference field [0127] 114 gray reference field [0128] 116 cut-out portion [0129] 116a beveled part of cut-out portion [0130] 118 optical test strip [0131] 120 reagent test region [0132] 122 position detection code element [0133] 124 corner [0134] 126 kit [0135] 128 mobile device [0136] 130 camera [0137] 132 processor [0138] 148 color reference field (black) [0139] 150 gray reference field [0140] 152 color reference field (white) [0141] 154 color reference field [0142] 160 central region of bottom surface [0143] 170 guide channel [0144] 172 orifice [0145] 174 engagement hook [0146] 210 providing an optical test strip [0147] 220 detachably connecting the optical test strip to a test strip fixation device [0148] 230 applying a sample of a body fluid to a reagent test region [0149] 240 capturing by a camera an image containing a part of the optical test strip and a part of the top surface of the test strip fixation device [0150] 250 determining the analyte concentration