Method for enhanced determination of analyte concentration in bodily fluid

Abstract

The invention relates to a computer-implemented analysis method for determining a concentration of an analyte in a bodily fluid by using a mobile device having at least one camera, the computer-implemented analysis method comprising: i) receiving at least one image captured by the camera of the mobile device, the image comprises at least a portion of a reagent test region associated with an optical test element and / or with a color reference card, the reagent test region being applied with a sample of the bodily fluid, said image further comprising at least a portion of at least one hydrochromic indicator zone associated with said optical test element and / or associated with said color reference card, wherein said hydrochromic indicator zone exhibits at least one optically detectable color change at a predetermined threshold level of relative humidity rHthreshold (m); ii) deriving an estimate of local relative humidity, rHestimate, from the color of the hydrochromic indicator zone in the image; and selecting one of at least two predetermined relative humidity application ranges rHappl-range (n) on the basis of the estimated value rHestimate, and selecting one of the at least two predetermined relative humidity application ranges rHappl-range (n) on the basis of the estimated value rHestimate; and iii) determining the concentration of the analyte from the color of the reagent test region in the image based on a color forming reaction at the reagent test region of the sample to which the bodily fluid is applied, taking into account the relative humidity application range rHappl-range (n) selected in step ii).

Description

Technical Field

[0001] The present invention relates to a method for determining the concentration of an analyte in a body fluid using at least one mobile device having a camera. Further, the present invention relates to a mobile device having a camera for implementing the method, to a kit comprising a mobile device having a camera, to a computer program, and to a computer-readable storage medium. The method, mobile device, computer program, and storage medium are specifically useful for medical diagnosis, for example in order to qualitatively or quantitatively detect one or more analytes in a body fluid, such as for detecting glucose in blood or interstitial fluid. Background Art

[0002] In the field of medical diagnosis, in many cases, it is necessary to detect one or more analytes in a body fluid sample such as blood, interstitial fluid, urine, saliva, or other types of body fluids. Examples of analytes to be detected are glucose, triglycerides, lactate, cholesterol, or other types of analytes that are normally present in these body fluids. If necessary, appropriate treatment can be selected based on the concentration and / or presence of the analyte.

[0003] Generally, devices and methods known to those skilled in the art use test elements containing one or more test chemicals that are capable of performing one or more detectable detection reactions, such as optically detectable detection reactions, in the presence of the analyte to be detected. Regarding the test chemicals contained in the test elements, reference can be made, for example, to J. Hoenes et al.: The Technology Behind Glucose Meters: Test Strips, Diabetes Technology & Therapeutics, Vol. 10, Supplement 1, 2008, S-10 to S-26.

[0004] In analytical measurements, specifically in analytical measurements based on color formation reactions, a technical challenge lies in evaluating the color change caused by the detection reaction. In addition to using dedicated analytical devices such as hand-held blood glucose meters, in recent years, the use of general-purpose electronic devices such as smart phones and portable computers or other mobile devices has become increasingly common.

[0005] Contrary to laboratory measurements and measurements performed using dedicated analytical measurement devices, when using a mobile computing device such as a smart phone, various additional effects need to be considered, such as, for example, lighting conditions and positioning aspects, which can be quite difficult to take into account. However, in order to improve the accuracy of the results of analyte detection in these cases, it is beneficial to appropriately consider any parameters known to be involved in the required analyte detection or measurement.

[0006] For an analytical measurement based on a test chemical, one such parameter is typically the temperature at which the reaction of the analyte with the test chemical takes place. For such test chemicals included in the test element, see, for example, the reference of J. Hoenes et al. cited above. In addition, another such parameter that can affect the test chemical is humidity, specifically the ambient humidity at the location of the measurement, which is typically expressed in the form of relative humidity.

[0007] When using a mobile device, one way to account for the temperature of the reaction on the test element is to provide a temperature sensor or a temperature indicating area on the test strip itself. See, for example: US9778200B2, which particularly describes a method for a portable computing device with an image sensor to read a reaction area on a test strip located in a peripheral device, where the test strip may include a temperature indicating area and the sample characteristics can be corrected based on the captured temperature indicating area in the image; and EP3018470A1, which particularly describes a method for terminally measuring biometric information, the method including: receiving an image of a biosensor including a reagent pad on which a sample is collected; wherein the method may further include determining the temperature of the sample based on temperature information indicated by a temperature measurer attached to the reagent pad in the received image; and US2013 / 267032A1 and EP3575781A2, which particularly relate to a sample test strip for detecting the characteristics of an analyte in a sample, where the sample test strip may include a temperature indicating area configured to correct the measurement of the characteristics of the analyte.

[0008] In contrast to the foregoing examples, where the analytical measurement can account for the influence of temperature, the analytical measurement involves using a test chemical based on color formation and involves using a mobile computing device such as a smartphone. In such scenarios, the influence of humidity has not been considered in the same way.

[0009] Examples of humidity-sensitive scenarios in non-diagnostic fields are described in US2021350689A1, which particularly relates to a workstation monitoring system including a camera for: receiving an image, identifying a surface and the state of the surface (including, for example, clean, dirty, contaminated, attended or unattended), tracking the behavior of an individual, the movement of an object and / or the appearance of a surface that causes a change in the state of the surface, and generating a trigger event signal based on the change in the state of the surface; wherein a unique identifier can be embedded in a sticker, for example hidden under a hydrochromic ink when the sticker is dry and visible only when the ink is wet and thus transparent, and the unique identifier can be read by a scanning mobile handheld device such as a mobile phone.

[0010] EP2941630B1 relates to a sample test strip for detecting the characteristics of an analyte in a sample, the sample test strip comprising: a reaction area; and a color calibration area; wherein the test strip further comprises: a path for the sample, the path being defined by a capillary extending from a capillary inlet to the reaction area; a hole passing through the capillary and defined between the capillary inlet and the reaction area; a top opening of the hole covered by a first transparent film; and a bottom opening of the hole covered by a second film. The test strip may further comprise a timer area for receiving the sample and linearly changing color in response to the sample; and the test strip may further comprise a timer area for changing color in response to light or humidity.

[0011] US2022 / 381773A1 relates to an analytical method for determining the concentration of an analyte in a body fluid using a mobile device having a camera and a processor, wherein local temperature information at the current location of the mobile device is used to determine a correction temperature and / or a correction temperature function, which are taken into account when determining the analyte concentration from an image captured by the camera based on a color formation reaction at a reagent test area of an optical test strip to which the body fluid is applied. In the described method, humidity information from various sources may be considered.

[0012] Although there are advantages involved in using mobile computing devices for the purpose of performing analytical measurements, one of the technical challenges that still remains is to properly account for the influence of humidity on the reaction involving the analyte to be detected and the test chemicals included in the test element.

[0013] Problems to be solved

[0014] Accordingly, it is desirable to provide devices and methods that at least partially address the foregoing challenges. Specifically, it is desirable to provide devices and methods that allow for the efficient determination of the concentration of an analyte in a body fluid based on a mobile in a reliable and accurate manner, yet with a small amount of setup and implementation effort, and which in particular should account for the influence of humidity. Summary of the invention

[0015] This problem is solved by: a computer-implemented analytical method for determining the concentration of an analyte in a body fluid by using at least one mobile device having a camera; further, a mobile device having a camera; a kit comprising the mobile device and an optical test strip and / or a color reference card; and a computer program and a computer-readable storage medium, having the features of the independent claims. Advantageous embodiments that may be implemented separately or in any arbitrary combination are listed in the dependent claims.

[0016] As used hereinafter, the terms "having", "including", or "comprising" or any grammatical variations thereof are used in a non-exclusive manner. Thus, these terms can either refer to a situation where no other features exist in the entity described in this context apart from the features introduced by these terms, or to a situation where one or more other features exist. By way of example, the statements "A has B", "A includes B", and "A comprises B" can either refer to a situation where no other elements exist in A apart from B (i.e., a situation where A consists of B alone and uniquely); or to a situation where one or more other elements (such as element C, elements C and D, or even other elements) exist in entity A apart from B.

[0017] Further, it should be noted that the terms "at least one", "one or more", or similar expressions indicating that a feature or element can exist once or more than once are generally used only once when introducing the corresponding feature or element. Hereinafter, in most cases, when referring to the corresponding feature or element, although the corresponding feature or element may exist only once or multiple times, the expressions "at least one" or "one or more" are not reused.

[0018] Further, as used hereinafter, the terms "preferably", "more preferably", "particularly", "more particularly", "specifically", "more specifically", or similar terms are used in conjunction with optional features without restricting alternative possibilities. Thus, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As those skilled in the art will recognize, the present invention can be carried out by using alternative features. Similarly, the features introduced by "in an embodiment of the present invention" or similar expressions are intended to be optional features without any limitation on alternative embodiments of the present invention, without any limitation on the scope of the present invention, and without any limitation on the possibility of combining the features introduced in this way with other optional or non-optional features of the present invention.

[0019] In a first aspect of the present invention, a computer-implemented, specifically in vitro analysis method for determining the concentration of an analyte in a body fluid is disclosed, the method comprising using a mobile device having at least one camera and specifically a processor. The method comprises the following steps, by way of example, the following steps may be carried out in a given order. However, it should be noted that different orders are also possible. Further, one or more method steps may be carried out once or repeatedly. Further, two or more method steps may be carried out simultaneously or in a timely coincidence manner. The method may include other method steps not listed. The method includes, in a first step i), specifically receiving, by the processor of the mobile device, at least one image captured by the camera of the mobile device. The image includes at least a part of a reagent test area associated with an optical test element and / or associated with a color reference card, wherein a sample of the body fluid is applied to the reagent test area. Further, the image includes at least a part of at least one hydrochromic indicator area associated with the optical test element and / or associated with the color reference card. The hydrochromic indicator area exhibits at least one optically detectable color change at a relative humidity rH at a predetermined threshold level threshold(m) below which

[0020] The method further comprises:

[0021] ii) specifically deriving, by the processor of the mobile device, an estimated value rH of the local relative humidity from the color of the hydrochromic indicator area in the image estimate .

[0022] Step ii) further includes specifically selecting, by the processor of the mobile device, at least two from at least three predetermined relative humidity applicable ranges rH estimate , specifically one of a predetermined relative humidity applicable range, based on the estimated value rH appl-range(n) .

[0023] The method still further comprises:

[0024] iii) specifically determining, by the processor of the mobile device, the concentration of the analyte from the color of the reagent test area in the image based on a color formation reaction at the reagent test area where the sample of the body fluid is applied

[0025] In step iii), the relative humidity applicable range rH selected in step ii) is taken into account when determining the analyte concentration appl-range(n) .

[0026] Without limiting the scope, the present invention may be specifically described with respect to blood glucose measurement. However, it should be noted that the present invention may also be used for other types of analytical measurements using test elements

[0027] As used herein, the term "determining the concentration of an analyte in a body fluid" (which is also referred to as an analytical measurement) is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art and is not limited to a special or custom meaning. The term can specifically refer to, but is not limited to, quantitatively and / or qualitatively determining at least one analyte in any sample or aliquot of a body fluid. For example, the body fluid can include one or more of blood, interstitial fluid, urine, saliva, or other types of body fluids, particularly blood. By way of example, the result of determining the concentration can be the concentration of the analyte and / or the presence or absence of the analyte to be determined. In particular, by way of example, the analytical measurement can be a blood glucose measurement, and thus the analytical measurement can yield, for example, a blood glucose concentration. In particular, the analytical measurement result value can be determined by the analytical measurement.

[0028] Accordingly, the term "analyte concentration value" (which is generally also referred to as the "analytical measurement result value") as used herein is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art and is not limited to a special or custom meaning. The term can specifically refer to, but is not limited to, a numerical indication of the concentration of an analyte in a sample.

[0029] By way of example, the at least one analyte can be or can include one or more specific chemical compounds and / or other parameters. By way of example, one or more analytes involved in metabolism, such as blood glucose, can be determined. Additionally or alternatively, other types of analytes or parameters, such as a pH value, can be determined.

[0030] As outlined above, the method includes using at least one mobile device having at least one camera. The term "mobile device" as used herein is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art and is not limited to a special or custom meaning. The term can specifically refer to, but is not limited to, a mobile electronic device, and more specifically can refer to a mobile communication device such as a mobile phone or a smart phone. Additionally or alternatively, the mobile device can also refer to a tablet computer or another type of portable computer having at least one camera and at least one processor.

[0031] As used herein, the term "camera" is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art and is not limited to a special or custom meaning. Specifically, the term can refer to, but is not limited to, a device having at least one imaging element configured to record or capture spatially resolved one-dimensional, two-dimensional or even three-dimensional optical data or information. By way of example, a camera can include at least one camera chip configured to record an image such as at least one CCD chip and / or at least one CMOS chip. As used herein but not limited thereto, the term "image" can specifically relate to data recorded by using a camera, such as a plurality of electronic readings from an imaging device, such as pixels of a camera chip.

[0032] In addition to at least one camera chip or imaging chip, a camera can further include additional elements, such as one or more optical elements, for example one or more lenses. By way of example, a camera can be a fixed-focus camera having at least one lens with a fixed adjustment relative to the camera. However, alternatively, a camera can also include one or more variable lenses that can be adjusted automatically or manually. The present invention should be particularly applicable to cameras commonly used in mobile applications, such as laptop computers, tablet computers or especially cellular phones such as smart phones. Thus, specifically, a camera can be part of a mobile device that, in addition to at least one camera, further includes one or more data processing devices such as one or more data processors. However, other cameras are also possible.

[0033] In this method, at least one image is received, the image including at least a portion of a reagent test area associated with one of: an optical test element and / or a color reference card. Specifically, the optical test element and / or the color reference card may be provided with a reagent test area. Additionally, if the reagent test area is provided on the optical test element, the color reference card may be adapted to be associated with the optical test element having the reagent test area. The reagent test area is adapted to receive a sample of body fluid, and when a sample of body fluid is applied to the reagent test area, the reagent test area is adapted to at least partially undergo a color-forming reaction. The reagent test area may also be referred to herein as a "test zone". As used herein, the term "optical test element" is a broad term and will be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, any element or device configured to perform a color change detection reaction. The optical test element may also be referred to as a test strip or a test element, where all three terms may refer to the same element. In particular, the optical test element and / or the color reference card may have a reagent test area that contains at least one test chemical for detecting at least one analyte. As an example, the optical test element may include at least one substrate such as at least one carrier, to which or in which at least one reagent test area is applied. In particular, the optical test element may further include one or more reference areas, such as a white area and / or a black area. Additionally or alternatively, the substrate or carrier itself may be or may include such reference areas. As an example, at least one carrier may be strip-shaped, such that the test element is a test strip. These test strips are generally widely used and provided. A test strip may carry a single test zone or multiple test zones, including the same or different test chemicals therein. The color reference card may include similar features for the optical test strip as described above herein. In particular, the color reference card may be provided in a credit card format, i.e., in the size and form of a conventional credit card made of plastic. Generally, such card-sized color reference cards exhibit multiple reference areas, such as white areas, black areas, and / or gray areas. Additionally or alternatively, the color reference card may exhibit multiple reference areas having various reference colors, the reference colors being colors other than white, black, or gray.

[0034] As used further herein, the term "reagent test area" (also referred to herein as "test area") is a broad term and will be given its ordinary and customary meaning to one of ordinary skill in the art and is not limited to a special or custom meaning. The term can specifically refer to, but is not limited to, a coherent amount of a test chemical, such as an area (e.g., a circular area, a polygonal area, or a rectangular area) having one or more layers of material, wherein the test chemical is included in at least one layer of the test area. As an example, for a test chemical included in an optical test strip, reference is made to J. Hoenes et al.: The Technology Behind Glucose Meters: Test Strips, Diabetes Technology & Therapeutics, Vol. 10, Suppl. 1, 2008, S-10 to S-26. Other types of test chemicals are possible and can be used to practice the present invention.

[0035] As described above, the method includes receiving at least one image of at least a portion of a reagent test area to which a sample of body fluid has been applied, the at least one image being captured by a camera of a mobile device. As used herein, the term "receiving at least one image" is a broad term and is given its ordinary and customary meaning to one of ordinary skill in the art and is not limited to a special or custom meaning. The term can specifically refer to, but is not limited to, one or more of imaging, image recording, image acquisition, and image capture. The term "receiving at least one image" can include receiving and / or capturing a single image and / or multiple images such as an image sequence. For example, the receiving and / or capturing of an image can include continuously recording an image sequence such as a video or movie. The receiving and / or capturing of at least one image can be initiated by a user action or can be automatically initiated, for example, once it is automatically detected that at least one object is present within the field of view and / or within a predetermined sector of the field of view of the camera. These automatic image acquisition techniques are known, for example, in the field of automatic barcode readers such as automatic barcode reading applications. For example, the receiving and / or capturing of an image can be performed by utilizing a stream or "live stream" of images acquired by the camera, wherein one or more of the images in the stream are automatically or by user interaction (such as pressing a button) stored and used respectively as at least one first image or at least one second image. Image acquisition can be supported by a processor of the mobile device, and the storage of the images can be performed in a data storage device of the mobile device.

[0036] The reception and / or capture of at least one image may include receiving and / or capturing at least one image in the case of applying a sample of body fluid to a test strip, and further optionally, receiving and / or capturing at least one image without applying a body fluid sample to the test strip, such as before capturing an image in the case of applying the sample to the test strip. The latter images can specifically be used for comparison purposes and can also be referred to as "blank images" or "dry images". For example, sample application can generally be carried out directly or indirectly, for example via at least one capillary element. At least one image received and / or captured after sample application can generally also be referred to as a "wet image", even if the sample may have dried by the time the image is actually captured. The wet image can generally be received and / or taken after having waited for at least a pre-determined waiting time (such as after five seconds or more) to allow the detection reaction to occur. Thus, as an example, the method can include waiting for at least a pre-determined minimum amount of time between receiving and / or taking at least one optional dry image and at least one wet image. The pre-determined minimum amount of time can specifically be sufficient for the detection reaction to occur in the test strip. As an example, the minimum amount of waiting time can be at least 5 s.

[0037] The method includes determining an analyte concentration, particularly an analyte concentration value, from the color formation in the reagent test area. Thus, the method can be an analytical measurement including a change in at least one optical property of an optical test element (such as an optical test strip), which change can be visually measured or determined using a camera. Specifically, the analytical measurement can be or can include a color formation reaction in the presence of at least one analyte to be determined. As used herein, the term "color formation reaction" is a broad term and will be given the ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or customized meaning. The term can specifically refer to, but is not limited to, a chemical, biological or physical reaction during which the color (specifically the reflectance) of at least one element participating in the reaction changes as the reaction proceeds. The color formation can be detected by a mobile device, such as by a processor of the mobile device, and can be quantitatively evaluated, such as by deriving from at least one image at least one parameter that quantifies or characterizes the color formation in the test area due to the presence of the analyte in the body fluid. For this purpose, one or more specific color coordinates can be used. Thus, the mobile device and specifically the processor of the mobile device can be configured to determine the color change by determining a change in one or more color coordinates that occurs due to the detection reaction.

[0038] The concentration of the analyte, particularly the analyte concentration value, is determined from the color formation in the test area. For this purpose, at least one image is used. For example, the analyte concentration value can be a numerical indication identifier of the analytical measurement result, such as indicating the concentration of at least one analyte in the sample, such as a blood glucose concentration.

[0039] The image received in step i) further includes at least a portion of at least one hydrochromic indicator region associated with the optical test element and / or associated with the color reference card, specifically associated with the color reference card. For example, at least one hydrochromic indicator region may be attached to the optical test element, or at least one hydrochromic indicator region may be attached to the color reference card. Alternatively or additionally, at least one hydrochromic indicator region may be provided separately from the optical test element and the color reference card, but may be used in conjunction with the optical test element and / or the color reference card. The hydrochromic indicator region exhibits at least one optically detectable color change at a relative humidity rH at one or more predetermined threshold levels threshold(m) below.

[0040] The relative humidity of an air-water mixture is defined as the ratio of the partial pressure of water vapor in the mixture to the equilibrium vapor pressure of water on a flat surface of pure water at a given temperature. In other words, relative humidity is the ratio of how much water vapor is in the air to how much water vapor the air could contain at a given temperature. Relative humidity is usually expressed as a percentage (also referred to herein as “%rH”, i.e., percentage relative humidity); a higher percentage means the air-water mixture is wetter. At 100% relative humidity, the air is saturated and at its dew point. As is known to those skilled in the art, common devices for measuring the humidity of air include psychrometers and hygrometers. An overview of such devices can be found, for example, in the following: Kohlrausch, F., Praktische Physik 1, Kose, V.; Wagner, S., Hrsg., 24. Aufl.; Teubner: Stuttgart, (1996), S. 400. Any relative humidity value used herein (also referred to herein as “rH” value) and any relative humidity level (including the threshold levels of relative humidity, e.g., rH threshold(m) 、rH threshold(m1) 、rH threshold(m2) and rH estimate ) are provided as numerical values with the unit of “%rH”, i.e., the percentage of relative humidity. Generally, any rH value mentioned herein may be associated with a given ambient temperature and / or a given ambient pressure. Generally speaking, in the context of the present invention, the ambient temperature may be any temperature from 0 °C to 65 °C, for example, any one of 0 °C, 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C and 65 °C, specifically, any temperature among 20 °C or 25 °C. In addition, generally speaking, in the context of the present invention, the ambient pressure may be any pressure from 900 hPa to 1080 hPa (mean sea level pressure, MSLP), for example, any one of 990 hPa, 1013 hPa, 1040 hPa.

[0041] In step ii), an estimated value rH of the local relative humidity is derived from the color of the hydrochromic indicator region in the image. estimate . The term "local" as used in this context refers to the relative humidity at the current location of the mobile device, such as an indoor location or an outdoor location. Additionally, the term "local" as used herein may refer to any place or area that can be specified or defined in order to appropriately represent or approximate the relative humidity conditions at or within the locally restricted surroundings of the mobile device. For example, particularly in the case where the current location of the mobile device is outdoors, it may be appropriate to refer to the relative humidity conditions of a region (such as a city, a part of a city, a neighborhood, a landscape or a part thereof, a county or a federal state, etc.). In this regard, "local relative humidity" may refer to information on relative humidity as provided by any common online weather service, provided that information on the local relative humidity is provided. Alternatively or additionally, if the current location of the mobile device is indoors, it may be appropriate to refer to the relative humidity conditions within the housing or within a room.

[0042] The method may further comprise the steps of: displaying an analyte concentration value on a display of the mobile device, such as. Additionally or alternatively, the method may comprise storing at least one analyte concentration value in at least one data storage device of the mobile device. Also additionally and alternatively, the method may further comprise transmitting at least one analyte concentration value to another computer, for example, via at least one interface and / or via at least one data transmission network for further evaluation, for example.

[0043] Thus, in a first aspect, the present invention particularly relates to a computer-implemented analytical method for determining the concentration of an analyte in a body fluid by using a mobile device having at least one camera and specifically having at least one processor, specifically an in vitro analytical method, the method comprising:

[0044] i) receiving, specifically by a processor of the mobile device, at least one image captured by a camera of the mobile device, the image comprising at least a portion of a reagent test region associated with an optical test element and / or associated with a color reference card, to which a sample of the body fluid is applied, the image further comprising at least a portion of at least one hydrochromic indicator region associated with the optical test element and / or associated with the color reference card, wherein the hydrochromic indicator region exhibits at least one optically detectable color change at a pre-determined threshold level of relative humidity rH threshold(m) , specifically at two or more different pre-determined threshold levels of relative humidity rH threshold(m) ;

[0045] ii) Specifically, an estimate value rH of the local relative humidity is derived by a processor of the mobile device from the color of the hydrochromic indicator region in the image estimate ; and specifically, by the processor of the mobile device, based on the estimate value rH estimate to select one of at least two predetermined relative humidity applicable ranges rH appl-range(n) specifically, one of at least three predetermined relative humidity applicable ranges; and

[0046] iii) Considering the relative humidity applicable range rH selected in step ii) appl-range(n) , specifically, a processor of the mobile device determines the concentration of the analyte from the color of the reagent test region in the image based on the color formation reaction at the reagent test region of the sample to which the body fluid is applied;

[0047] where each of rH threshold(m) and rH estimate is an rH value provided in the form of " % rH" (i.e., as a relative humidity percentage).

[0048] The proposed method provides an effective mobile - based determination of the concentration of the analyte in the body fluid for performing the method by considering information on relative humidity at the current location of the mobile device. Information on the local relative humidity is obtained from hydrochromic indicator regions, which are obtained with low input and are cost - effective. Thus, reliable accuracy of analyte measurement can be effectively achieved especially with low input for setup and implementation.

[0049] The image received in step i) includes at least a part of at least one hydrochromic indicator region. The hydrochromic indicator region exhibits at least one optically detectable color change at one or more, for example, at 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 predetermined threshold levels of relative humidity rH threshold(m) ; specifically, at one or two, or alternatively, at two or more, for example, at two or three, or still alternatively, at three or more, for example, at 3, 4, 5, 6 or 7 different predetermined threshold levels of relative humidity rH threshold(m) Specifically, the hydrochromic indicator region may include one or more individual hydrochromic indicator regions, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Each of the individual hydrochromic indicator regions exhibits at least one, specifically an optically detectable color change, at a predetermined threshold level of relative humidity rH threshold(m) where the predetermined threshold level of relative humidity rH threshold(m)may be partly the same, i.e., there may be at least some redundant individual hydrochromic indicator regions, or wherein the relative humidity rH of the predetermined threshold level threshold(m) may each be different from one another. For example, the hydrochromic indicator region may comprise a specific number of individual hydrochromic indicator regions, e.g., in the range from 1 to 10, such as 3, 4, 5, 6, or 7, and each of the specific number of individual hydrochromic indicator regions exhibits an optically detectable color change at a different predetermined threshold level of relative humidity rH threshold(m) Thus, such a hydrochromic indicator region may comprise 7 individual hydrochromic indicator regions, and each of the individual hydrochromic indicator regions exhibits an optically detectable color change at a different predetermined threshold level of relative humidity rH threshold(m) wherein the relative humidity rH of the predetermined threshold level threshold(1) = 20% rH, rH threshold(2) = 30% rH, rH threshold(3) = 40% rH, rH threshold(4) = 50% rH, rH threshold(5) = 60% rH, rH threshold(6) = 70% rH and rH threshold(7) = 80% rH. Providing at least one hydrochromic indicator region in the form of a plurality of individual hydrochromic indicator regions can significantly facilitate the detection of local relative humidity, which in step ii) is derived from the color of the hydrochromic indicator region in the image: Since the position of the individual hydrochromic indicator regions in the image can be known or predetermined, e.g., by their known positions on the optical test element and / or the color reference card, it is easier and thus more accurate to determine the color change occurring at any of such known or predetermined positions. Therefore, from such an arrangement of at least one hydrochromic indicator region, an estimate rH of the local relative humidity can be more reliably derived in step ii) estimate . However, for the purposes of the present invention, it is also feasible for one or more individual hydrochromic indicator regions to exhibit more than one color change at two or more different predetermined threshold levels of relative humidity rH threshold(m)

[0050] ​The materials for the water-responsive color indicator region to be used in this article can provide reversible or irreversible color changes, specifically reversible color changes. Suitable color-changing materials are commercially available and can include, for example, compounds selected from the list comprising cobalt dichloride, cobalt dibromide, and copper oxide. Such color-changing materials can be obtained commercially, for example, from LongLife for Art (Germany), see https: / / llfa.eu. Generally, such color-changing materials are provided in the form of test papers impregnated with a solution of the material.

[0051] If each of at least one optically detectable color change occurs substantially completely within at least one narrow interval of rH values, where each of the at least one narrow intervals of rH values is centered on at least one of the relative humidities rH at a pre-determined threshold level threshold(m) then it is particularly useful. Specifically, each of the at least one narrow intervals of rH values can include rH values spanning a range of no more than 15% rH; and more specifically, no more than 10% rH; and even more specifically, no more than 5% rH. In this context, the term "substantially completely" can refer to the degree of color change from a first color to a second color, where the second color is clearly distinguishable from the first color; specifically, where the color change from the first color to the second color occurs to an extent of at least 80%; more specifically, where the at least 80% degree of color change occurs between 10% and 90% of the degree of color change, in each case the degree of color change relative to the complete color change from the first color to the second color, which represents 100% of the degree. Additionally, in this context, the term "centered on... substantially" can refer to a configuration where the relative humidity rH at a pre-determined threshold level threshold(m) represents a given rH value, such as 30% rH, and the narrow interval of rH values (e.g., a range of up to 10% rH values) is adapted such that the relative humidity rH at a pre-determined threshold level threshold(m) is at least approximately at the center of the narrow interval of rH values; thus, in this example, with the relative humidity rH at a pre-determined threshold level threshold(m) being 30% rH, the narrow interval of rH values covering a range of up to 10% rH values gives a range of rH values from 25% rH to 35% rH, which is equal to 30% rH ± 5% rH.

[0052] In step i), the pre-determined threshold level or the relative humidity rH of the threshold level threshold(m)may include one or more rH values selected from 10% rH, 15% rH, 20% rH, 25% rH, 30% rH, 45% rH, 50% rH, 55% rH, 60% rH, 65% rH, 70% rH, 75% rH, and 80% rH. For example, the hydrochromic indicator region may exhibit an optically detectable color change at a relative humidity at a following predetermined threshold level: rH threshold(1) = 20% rH, rH threshold(2) = 30% rH, rH threshold(3) = 40% rH, rH threshold(4) = 50% rH, rH threshold(5) = 60% rH, rH threshold(6) = 70% rH, rH threshold(7) = 80% rH. As another example, the hydrochromic indicator region may exhibit an optically detectable color change at a relative humidity at a following predetermined threshold level: rH threshold(1) = 30% rH, rH threshold(2) = 40% rH, rH threshold(3) = 50% rH.

[0053] Specifically, at least one hydrochromic indicator region may include one or more individual hydrochromic indicator regions, each of the one or more individual hydrochromic indicator regions exhibiting at least one optically detectable color change independently of each other at a relative humidity rH at specifically different predetermined threshold levels threshold(m) wherein the relative humidity rH at the predetermined threshold levels threshold(m) in each case includes one or more, specifically one, rH value selected from 10% rH, 15% rH, 20% rH, 25% rH, 30% rH, 45% rH, 50% rH, 55% rH, 60% rH, 65% rH, 70% rH, 75% rH, and 80% rH.

[0054] In step ii), an estimated value rH of the local relative humidity is specifically derived by a processor of the mobile device from the color of the hydrochromic indicator region in the image estimate . Specifically, when the hydrochromic indicator region exhibits an optically detectable color change at a relative humidity rH at a specific predetermined threshold level threshold(m) , for example, at rH threshold(m) = 30% rH, then the estimated value rH of the local relative humidity derived therefrom estimate may be at least substantially equal to the relative humidity rH at the specific predetermined threshold level threshold(m) such that an estimated value of the local relative humidity of rH estimate = 30% rH can be produced.

[0055] If at least one hydrochromic indicator zone comprises more than one separate hydrochromic indicator zone, for example 7, each of which exhibits an optically detectable color change at different predetermined threshold levels of relative humidity rH threshold(m) e.g., at rH thresholds equal to 20% rH, 30% rH, 40% rH, 50% rH, 60% rH, 70% rH and 80% rH, then the estimated value of the local relative humidity rH estimate derived therefrom may be equal to the highest one of all these predetermined threshold levels of relative humidity rH threshold(m) at which an optically detectable color change actually occurs when performing the method. In this case, for the foregoing 7 different predetermined threshold levels of relative humidity rH threshold(m) as an example, if five predetermined threshold levels of relative humidity rH threshold(1) = 20% rH, rH threshold(2) = 30% rH, rH threshold(3) = 40% rH, rH threshold(4) = 50% rH and rH threshold(5) = 60% rH actually exhibit an optically detectable color change when performing the method, then an estimated value of the local relative humidity rH estimate = 60% rH may be generated; where the remaining two predetermined threshold levels of relative humidity rH threshold(6) = 70% rH and rH threshold(7) = 80% rH do not actually exhibit such an optically detectable color change when performing the method because their corresponding rH threshold values rH threshold(m) are higher than the actual local relative humidity.

[0056] Alternatively, other ways may be envisioned herein for specifically deriving an estimated value of the local relative humidity rH estimate from the color of the hydrochromic indicator zone in the image by the processor of the mobile device.

[0057] In step ii), in addition, specifically by the processor of the mobile device, based on the estimated value of the local relative humidity rH estimate to select one of at least two predetermined applicable ranges of relative humidity rH appl-range(n) , specifically one of at least three predetermined applicable ranges of relative humidity. Specifically, a predetermined applicable range of relative humidity rH appl-range(n) may be selected such that it includes the estimated value of the local relative humidity rH estimate . For example, if the estimated value of the local relative humidity is rH estimate = 70% rH, then the predetermined applicable range of relative humidity rH appl-range(n), which includes an rH value of >60%, e.g., an rH value of >60% to ≤90% rH.

[0058] Specifically, in step ii), at least two, specifically at least three, pre-determined relative humidity application ranges rH appl-range(n) are different from each other and do not overlap with each other. Generally, at least two, specifically at least three, pre-determined relative humidity application ranges rH appl-range(n) are defined such that they form a continuous range of rH values. Such a continuous range of rH values can span an rH value range from 0% rH to 100% rH (e.g., 0% rH to 90% rH or 10% rH to 80% rH). Specifically, the upper threshold rH value of the pre-determined relative humidity application range (e.g., an rH value having <30% rH and thus having an rH threshold(k) with an upper threshold of 30% rH appl-range(1)_low (where the threshold rH value of 30% rH is excluded from the first rH value range)) itself can be the lower threshold for another adjacent pre-determined relative humidity application range (e.g., an rH value having ≥30% rH and thus having an rH threshold(k1) with a lower threshold of 30% rH appl-range(2)_high (where the threshold rH value of 30% rH is included in the second rH value range)).

[0059] If there are two pre-determined relative humidity application ranges rH appl-range(n) , the first pre-determined relative humidity application range can be a low relative humidity range, e.g., an rH having an rH value of <30% rH appl-range(1) , and the second pre-determined relative humidity application range can be a high relative humidity range, e.g., an rH having an rH value of >60% rH appl-range(2) . Generally, at least two pre-determined relative humidity application ranges rH appl-range(n) can include: a first relative humidity application range rH appl-range(1)_low having an rH value X1 such that 0 < X1 rH < rH threshold(k) ; and a second relative humidity application range rH rH having an rH value X2 such that rH appl-range(2)_high ≤ X2 threshold(k) < 100% rH . rH .

[0060] Alternatively, at least two pre-determined relative humidity application ranges rH appl-range(n) can include at least three pre-determined relative humidity application ranges rH appl-range(n) . Specifically, at least three pre-determined relative humidity application ranges rH appl-range(n)may include at least a first relative humidity range rH appl-range(1)_low that has an rH value X1 rH for 0 < X1 threshold(k1) < rH rH ; and a second relative humidity range rH appl-range(2)_medium that has an rH value X2 threshold(k1) for rH rH ≤ X2 threshold(k2) ≤ rH rH ; and a third relative humidity range rH appl-range(3)_high that has an rH value X3 threshold(k2) for rH rH < X3 rH .

[0061] Regarding the foregoing exemplary rH ranges, in particular, rH threshold(k) can be an rH value selected from among 15% rH, 30% rH, 45% rH, 60% rH, and 75% rH; or rH threshold(k1) can be an rH value selected from among 15% rH, 20% rH, 25% rH, 30% rH, 35% rH, and 40% rH, and rH threshold(k2) can be an rH value selected from among 50% rH, 55% rH, 60% rH, 65% rH, 70% rH, and 75% rH. Specifically, rH threshold(k) can be an rH value selected from among 30% rH and 60% rH. Alternatively, rH threshold(k1) can be an rH value selected from among 25% rH, 30% rH, and 35% rH, and rH threshold(k2) can be an rH value selected from among 55% rH, 60% rH, and 65% rH.

[0062] Herein, each of X1 rH , X2 rH , X3 rH , rH threshold(m) , rH threshold(k) , rH threshold(k1) , and rH threshold(k2) is respectively an rH value provided in units of “% rH” specifically at a given ambient temperature and / or at a given ambient pressure.

[0063] In step iii), specifically, the processor of the mobile device determines the concentration of the analyte in the body fluid from the color of the reagent test area in the image based on the color formation reaction at the reagent test area of the sample to which the body fluid is applied. Determining the concentration of the analyte takes into account the relative humidity range rH appl-range(n) selected in step ii).

[0064] Advantageously, determining the concentration of the analyte in step iii) may specifically include, for each case independently of one another by a processor of the mobile device, determining at least one relative humidity correction value rH appl-range(n) based on one of the relative humidity applicable ranges rH corr selected in step ii), and / or at least one relative humidity correction function rH corr-fct . The at least one relative humidity correction value rH corr and / or the at least one relative humidity correction function rH corr-fct may be considered in step iii) to determine the concentration of the analyte.

[0065] As used herein, the term "relative humidity correction value rH corr " is a broad term and will be given its ordinary and customary meaning to a person of ordinary skill in the art and is not limited to a special or custom meaning. The term may specifically refer to, but is not limited to, one or more of a specified relative humidity value, an average relative humidity value, a representative relative humidity value, a reference relative humidity value, a relative humidity value range, and an incremental relative humidity value, particularly an incremental relative humidity value from a reference relative humidity value. Additionally or alternatively, the term "relative humidity correction value rH corr " may refer to, but is not limited to, one or more of an incremental analyte concentration value, an average incremental analyte concentration value, a representative incremental analyte concentration value, a reference incremental analyte concentration value, and an incremental analyte concentration value range; specifically, an incremental analyte concentration value. The term "relative humidity correction function rH corr-fct " may refer to a mathematical function, factor, formula, or algorithm, each of which may be applied to the determination of the analyte concentration in step iii). Specifically, the term "relative humidity correction function rH corr-fct " may include, but is not limited to, using one or more of a specified relative humidity value, an average relative humidity value, a representative relative humidity value, a reference relative humidity value, a relative humidity value range, an incremental relative humidity value, an incremental analyte concentration value, an average incremental analyte concentration value, a representative incremental analyte concentration value, a reference incremental analyte concentration value, and an incremental analyte concentration value range. For a practical implementation, the "relative humidity correction value rH corr " and / or the "relative humidity correction function rH corr-fct " advantageously include an incremental analyte concentration value. The pre-determined relative humidity applicable range rH estimate selected in step ii) derived from an estimated value rH appl-range(n) of the local relative humidity may be used as an input or as a trigger for applying the function, factor, formula, or algorithm in the determination of the analyte concentration in step iii). Generally speaking, the "relative humidity correction value rH corr " and the "relative humidity correction function rHcorr-fct ” can be used to appropriately account for any effect of relative humidity on chemical reactions as used herein in the reagent test area of the optical test element. Such effects can be determined empirically by a person skilled in the art for any particular type of chemical test reagent, for example. In some cases, the determination of the analyte concentration in step iii) based on the color formation reaction at the reagent test area can be assumed to occur at a typical relative humidity, such as at an ambient relative humidity of, for example, about 45% rH. In such cases, any effect of relative humidity on the chemical reaction may not be explicitly represented by a factor, formula, or algorithm that uses the local relative humidity as an input; in these cases, the “relative humidity correction value rH corr ” can be determined to be set to the ambient relative humidity, such as 45% rH. Alternatively, in these cases, the “relative humidity correction function rH corr-fct ” can be determined to be a multiplication factor equal to “1”, i.e., it does not affect the calculation of the analyte concentration.

[0066] Relative humidity application range rH appl-range(n) One or more (optionally each) of can be associated with their own relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct Specifically, the relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct can be selected independently of each other for each relative humidity application range rH appl-range(n)

[0067] In particular, it is conceivable that at least one of the relative humidity application ranges rH appl-range(n) is not associated with the relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct such that for the at least one of the relative humidity application ranges rH appl-range(n) , the determination of the concentration of the analyte is made without considering the correction value for relative humidity. For example, the relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct can be associated with a relative humidity application range rH appl-range(n) having a high rH value (such as having an rH value X2 threshold(k) ≤X2 rH of rH value X2 rH of rH appl-range(2)_high , for example where rH threshold(k) = 30% rH or where rH threshold(k) = 60% rH), while another relative humidity application range rH appl-range(n) having a low rH value (such as having 0 < X1 rH ​<rH threshold(k) The rH value X1 rH of rH appl-range(1)_low , for example, where rH threshold(k) = 30% rH or where rH threshold(k) = 60% rH) is not associated with the relative humidity correction value rH corr and / or the relative humidity correction function rH corr-fct . Additionally or alternatively, the relative humidity correction value rH corr and / or the relative humidity correction function rH corr-fct can be provided in a form, for example, in the form of a number, factor, parameter, and / or function, such that for the relative humidity application range rH appl-range(n) , when considering the relative humidity correction value rH corr and / or the relative humidity correction function rH corr-fct to determine the concentration of the analyte in step iii), the correction value for relative humidity is effectively not applied.

[0068] Specifically, in step iii), considering the at least one relative humidity correction value rH corr and / or the at least one relative humidity correction function rH corr-fct may further include associating one or more, specifically one, two, or three, more specifically each, of the relative humidity correction value rH corr and / or the relative humidity correction function rH corr-fct with a predefined concentration range of the analyte concentration independently of each other. The predefined concentration range can be selected from at least two, specifically from at least three predefined analyte concentration ranges. Specifically, the predefined analyte concentration ranges are different from each other and do not overlap with each other.

[0069] In this regard, similar to the case of the generally predefined relative humidity application range rH appl-range(n) described above, generally at least two, specifically at least three predefined analyte concentration ranges are defined such that they form a continuous range of analyte concentration values. Such a continuous range of analyte concentration values can span the entire range of analyte concentration values that can be obtained for any specific analyte in a body fluid. Specifically, similar to what has been described above for the predefined relative humidity application range rH appl-range(n) , the upper threshold analyte concentration value of the predefined analyte concentration range (which may not include the threshold concentration value, for example) itself can be the lower threshold analyte concentration value of another adjacent predefined analyte concentration range (which may include the threshold concentration value, for example).

[0070] Specifically, it is contemplated that at least one of the predefined concentration ranges of the analyte concentration is not associated with the relative humidity correction value rH corr and / or the relative humidity correction function rH corr-fct , such that for at least one of the predefined concentration ranges of the analyte concentration, the determination of the concentration of the analyte in step iii) is performed without considering the correction value for relative humidity. Additionally or alternatively, for at least one of the predefined concentration ranges of the analyte concentration, the relative humidity correction value rH corr and / or the relative humidity correction function rH associated therewith corr-fct can be provided, for example, in the form of a number, factor, parameter, and / or function, such that for at least one of the predefined concentration ranges of the analyte concentration, the determination of the concentration of the analyte in step iii) is performed without considering the correction value for relative humidity.

[0071] In a particular aspect, the method described above herein may further include specifically receiving, by the mobile device, at least one additional estimate value rH of the local relative humidity from at least one of the following add-estimate :

[0072] a) A remote weather service, via a wireless connection with the mobile device;

[0073] b) An external electronic device including an environmental humidity sensor, via a wireless connection with the mobile device; and

[0074] c) An environmental humidity sensor located in the mobile device.

[0075] In addition, step ii) may include validating or adjusting, by the processor of the mobile device, the estimated value rH of the local relative humidity by considering at least one of the additional estimate values rH add-estimate estimate .

[0076] Herein, each of rH estimate and rH add-estimate is respectively an rH value specifically provided in the form of "%rH" at a given ambient temperature and / or at a given ambient pressure.

[0077] Specifically, the external electronic device may be selected from one or more of the following: wearable devices such as fitness trackers, smart watches, smart glasses, smart clothing; smart home components such as electronic heating systems, smart temperature measurement units, home weather stations; and body-worn sensors such as non-invasive analyte measurement sensors, provided that the corresponding external electronic device includes an environmental humidity sensor and the ability to be wirelessly connected to the mobile device, for example, via WiFi, Bluetooth, BLE, etc.

[0078] ​In another aspect, the present invention relates to a mobile device having at least one camera and at least one processor, the mobile device being configured to determine the concentration of an analyte in a body fluid, wherein at least one concentration of the analyte is determined from a color-forming reaction at a reagent test area; and wherein the mobile device is further configured to perform the computer-implemented analysis method described herein, specifically at least steps i) to iii) of the computer-implemented in vitro analysis method.

[0079] In another aspect, the present invention relates to a kit comprising

[0080] - a mobile device having at least one camera and at least one processor, the mobile device being configured to determine the concentration of an analyte in a body fluid, wherein at least one concentration of the analyte is determined from a color-forming reaction at a reagent test area; and wherein the mobile device is further configured to perform the computer-implemented analysis method described herein, specifically at least steps i) to iii) of the computer-implemented in vitro analysis method; and

[0081] - at least one of an optical test element and a color reference card, the optical test element and / or the color reference card being associated with the reagent test area.

[0082] In another aspect, the present invention relates to a computer program comprising instructions which, when executed by

[0083] - a mobile device having at least one camera and at least one processor, the mobile device being configured

[0084] to determine the concentration of an analyte in a body fluid, wherein at least one concentration of the analyte is determined from a color-forming reaction at a reagent test area; and wherein the mobile device is further configured to perform the computer-implemented analysis method described herein, specifically at least steps i) to iii) of the computer-implemented in vitro analysis method;

[0085] cause the mobile device to implement the computer-implemented analysis method described herein, specifically at least steps i) to iii) of the computer-implemented in vitro analysis method.

[0086] In another aspect, the present invention relates to a computer-readable storage medium comprising instructions which, when executed by

[0087] - A mobile device having at least one camera and at least one processor, the mobile device being configured to determine the concentration of an analyte in a body fluid, wherein at least one concentration of the analyte is determined from a color-forming reaction at a reagent test area; and wherein the mobile device is further configured to perform the computer-implemented analysis methods described herein, specifically at least steps i) to iii) of the computer-implemented in vitro analysis method;

[0088] These instructions cause the mobile device to implement the computer-implemented analysis methods described herein, specifically at least steps i) to iii) of the computer-implemented in vitro analysis method. BRIEF DESCRIPTION OF THE DRAWINGS

[0089] Figure 1 Shows the effect of humidity on blood glucose measurement values.

[0090] Figure 2 Shows several examples of relative humidity correction functions rH corr-fct of.

[0091] Figure 3 Shows an embodiment of a kit and a mobile device for performing analytical measurements illustrated in perspective view.

[0092] Figure 4 Illustrates a flowchart of an exemplary embodiment for implementing the method of the present invention.

[0093] Herein, all rH values mentioned are provided in the form of "% rH" (i.e., percentage relative humidity), including for example rH threshold(m) , rH threshold(k) , rH estimate etc.

[0094] Figure 1 Shows the effect of humidity on blood glucose measurement values in the analyte concentration range below 120 mg / dl without applying the correction value for relative humidity, the blood glucose measurement values being measured by the program using the Active optical test strips from Roche Diabetes Care GmbH (Germany). At higher analyte concentrations (not shown) of about 450 mg / dl, no significant dependence on relative humidity is observable.

[0095] In Figure 1 , the deviations of the measurement values (which can be attributed to the influence of relative humidity) are expressed as the incremental concentration percentage relative to the average measurement value at 45% rH. The indicated lines represent the average values of the deviations at 15% rH, 45% rH, and 85% rH, respectively.

[0096] Figure 2 Shows several relative humidity correction functions rH corr-fct Examples, each of the several relative humidity correction functions being associated with one of a plurality of relative humidity applicable ranges rH appl-range(n) In this example, each relative humidity correction function rH corr-fct Is associated with one of three relative humidity applicable ranges rH appl-range(n) Specifically, the first relative humidity correction function rH corr-fct(1) Is associated with the first relative humidity applicable range rH appl-range(1)_low Which has an rH value X1 of 0 < X1 rH < rH threshold(k1) Where rH rH = 30% rH; and the second relative humidity correction function rH threshold(k1) Is associated with the second relative humidity applicable range rH corr-fct(2) Which has an rH value X2 of rH appl-range(2)_medium ≤ X2 threshold(k1) ≤ rH rH Where rH threshold(k2) = 30% rH and where rH rH = 60% rH; and the third relative humidity correction function rH threshold(k1) Is associated with the third relative humidity applicable range rH threshold(k2) Which has an rH value X3 of rH corr-fct(3) < X3 appl-range(3)_high Where rH threshold(k2) < X3 rH Where rH rH = 60% rH threshold(k2) = 60% rH

[0097] In addition, in Figure 2 Each of the three relative humidity correction functions rH corr-fct(1) 、rH corr-fct(2) And rH corr-fct(3) Is associated with three predefined concentration ranges of the analyte concentration. Specifically, the first predefined concentration range of the analyte concentration has a concentration value of 0 mg / dl to < 120 mg / dl; the second predefined concentration range of the analyte concentration has a concentration value of 120 mg / dl to 200 mg / dl; and the third predefined concentration range of the analyte concentration has a concentration value of > 200 mg / dl. Thus, if the measured value is measured within the first analyte concentration range below 120 mg / dl, then for the three relative humidity applicable ranges rH appl-range(n)For each of them, a constant correction value is applied to determine the concentration of the analyte in step iii), and each of the three relative humidity applicable ranges has its own relative humidity correction function rH corr-fct . In the second analyte concentration range (120 mg / dl – 200 mg / dl), for two of the three relative humidity applicable ranges rH appl-range(n) , the correction factor applied to the measured value decreases linearly until a correction factor of 1 is obtained, such that the correction value for relative humidity is no longer considered. In the third analyte concentration range > 200 mg / dl, for each of the three relative humidity applicable ranges rH appl-range(n) , the correction value for relative humidity is not applied or not considered.

[0098] In Figure 3 , an embodiment of a kit 148 and a mobile device for performing an analytical measurement is illustrated in perspective. The kit 148 includes at least one mobile device 112 and at least one optical test element 118, namely a test strip configured to perform a color change detection reaction. The mobile device 112 having a camera 114 may further include a processor 149. The mobile device 112 (specifically by using the processor 149) may be configured to perform the methods described herein. The optical test element 118 is an optical test strip. In particular, the optical test strip 118 may specifically have at least one reagent test area 120, and the reagent test area 120 contains at least one test chemical for detecting at least one analyte in a sample. The optical test strip 118 further includes a hydrochromic indicator area 121. As Figure 3 shown, the mobile device 112 may capture at least one image 124 of at least a portion of the reagent test area 120 associated with the optical test strip 118 by using the camera 114.

[0099] Figure 4 Illustrates a flowchart of an exemplary embodiment of a method for practicing the present invention using a kit as Figure 3 shown.

[0100] A computer-implemented in vitro analytical method for determining the concentration of an analyte in a body fluid by using a mobile device 112 having at least one camera 114 and at least one processor 149 includes, in a first step i), as depicted by reference numeral 100 in Figure 4 , specifically receiving, by the processor 149 of the mobile device 112, at least one image 124 captured by the camera 114 of the mobile device 112. Herein, the image 124 includes at least a portion of the reagent test area 120 associated with the optical test element 118. Alternatively, the image 124 including at least a portion of the reagent test area 120 may be associated with a color reference card 118. The reagent test area 120 has a sample of body fluid applied thereto.

[0101] In addition, the image 124 includes at least a portion of at least one hydrochromic indicator region 121 associated with the optical test element 118. Alternatively, the hydrochromic indicator region 121 may be associated with the color reference card 118. The hydrochromic indicator region 121 exhibits at least one optically detectable color change at a pre-determined threshold level of relative humidity rH threshold(m) below. For example, the hydrochromic indicator region 121 may exhibit an optically detectable color change at two or more different pre-determined threshold levels of relative humidity rH threshold(m) below. Advantageously, the at least one hydrochromic indicator region 121 includes a plurality of individual hydrochromic indicator regions, each of which exhibits an optically detectable color change at a different pre-determined threshold level of relative humidity rH threshold(m) below. The pre-determined threshold level of relative humidity rH threshold(m) in each case (i.e., for each of the individual hydrochromic indicator regions) may include rH values selected from 10% rH, 15% rH, 20% rH, 25% rH, 30% rH, 45% rH, 50% rH, 55% rH, 60% rH, 65% rH, 70% rH, 75% rH, and 80% rH. For example, the following 7 different rH values may be selected as the pre-determined threshold level of relative humidity rH threshold(1) to rH threshold(7) : 20% rH, 30% rH, 40% rH, 50% rH, 60% rH, 70% rH, and 80% rH.

[0102] Generally speaking, each of the at least one optically detectable color changes occurs substantially entirely within a narrow interval of rH values. Each of the narrow intervals of rH values may be centered on one of the pre-determined threshold levels of relative humidity rH threshold(m) . Advantageously, each of the narrow intervals of rH values includes rH values spanning a range of no more than 15% rH.

[0103] Figure 4 The exemplary embodiment shown for implementing the method further includes, in the second step ii), by Figure 4 depicted by the reference numeral 200 in the drawing, specifically, the processor 149 of the mobile device 112 derives an estimated value rH of the local relative humidity from the color of the hydrochromic indicator region 121 in the image 124 estimate . In the example of 7 individual hydrochromic indicator regions, each of these individual hydrochromic indicator regions exhibits a different pre-determined threshold level of relative humidity rH threshold(1) to rH threshold(7)exhibits an optically detectable color change at one of the rH values (having rH values of 20% rH, 30% rH, 40% rH, 50% rH, 60% rH, 70% rH, and 80% rH respectively), and the estimated value rH of the local relative humidity estimate can be equal to the relative humidity rH of all these predetermined threshold levels that actually exhibit an optically detectable color change when performing this method threshold(m) of the highest one, while for the relative humidity rH of the other remaining predetermined threshold levels threshold(m) (having an rH threshold value higher than the actual local humidity), no optically detectable color change is actually observed when performing this method. Therefore, if in this example, when performing this method, optically detectable color changes are actually observed only for these two of the seven individual hydrochromic indicator regions with relative humidity rH threshold(1) = 20% rH and rH threshold(2) = 30% rH, then the estimated value of the local relative humidity with rH estimate = 30% rH can be derived in step ii).

[0104] Furthermore, step ii) (reference numeral 200) includes specifically selecting, by the processor 149 of the mobile device 112, based on the estimated value rH estimate one of at least two predetermined applicable ranges of relative humidity rH appl-range(n) . For example, one of the at least three predetermined applicable ranges of relative humidity rH Figure 2 shown in the figure can be selected, that is, the first applicable range of relative humidity rH appl-range(n) (having an rH value X1 appl-range(1)_low where 0 < X1 rH < rH threshold(k1) < X1 rH , where rH threshold(k1) = 30% rH), the second applicable range of relative humidity rH appl-range(2)_medium (having an rH value X2 threshold(k1) where rH rH ≤ X2 threshold(k2) ≤ rH rH , where rH threshold(k1) = 30% rH and where rH threshold(k2) = 60% rH) and the third applicable range of relative humidity rH appl-range(3)_high (having an rH value X3 threshold(k2) where rH rH < X3 rH , where rH threshold(k2) = 60% rH). Therefore, based on the rH derived in the example above in this article estimateEstimated value of the local relative humidity of 30% rH, select the second relative humidity applicable range rH appl-range(2)_medium (having rH threshold(k1) ≤X2 rH ≤rH threshold(k2) rH value X2 rH , where rH threshold(k1) = 30% rH and where rH threshold(k2) = 60% rH).

[0105] Figure 4 The exemplary implementation for implementing this method shown further includes, in the third step iii), as depicted by reference numeral 300 in Figure 4 , specifically, the processor 149 of the mobile device 112 determines the concentration of the analyte from the color of the reagent test area 120 in the image based on the color formation reaction at the reagent test area 120 of the sample to which the body fluid is applied. Here, consider the relative humidity applicable range rH selected in step ii) appl-range(n) , for example, the second relative humidity applicable range rH above in this article appl-range(2)_medium . As an example, it can be assumed that the second relative humidity applicable range rH with rH values from 30% rH to 60% rH appl-range(2)_medium represents a range of medium relative humidity values, that is, neither including particularly low rH values (e.g., <30% rH) nor including particularly high rH values (e.g., >60% rH); such medium relative humidity values may have only a relatively limited impact on the measured values of the analyte concentration in the body fluid. For example, this is illustrated in Figure 1 , where the intermediate rH value range (30% rH to 60% rH) represents a reference for both the rH value range with a relatively low rH value (<30% rH) and the rH value range with a relatively high rH value (>30% rH), and where it is illustrated that for both of the rH ranges with low and high rH values respectively, significant deviations in the measured blood glucose concentration occur when affected by a relatively low rH value (such as 15% rH) or a relatively high rH value (such as 85% rH). Therefore, when considering the relative humidity applicable range rH selected in step ii) appl-range(2)_medium , when determining the concentration of the analyte from the color of the reagent test area 120 in the image in step iii), it may be appropriate not to apply a correction value for relative humidity. This situation is illustrated by a dashed line in Figure 2 , the dashed line representing the relative humidity applicable range rH appl-range(2)_medium .

[0106] On the other hand, if the measurement of blood glucose concentration is carried out at a relatively low rH value (such as 15% rH) or a relatively high rH value (such as 85% rH), correction for the influence of relative humidity may be appropriate; inFigure 1 Deviations in the measured blood glucose concentration that occur under the influence of such low or high rH values are illustrated by a cross (“x”, for 15% rH) and by a plus sign (“+”, for 85% rH), respectively. Thus, for the purpose of giving an example, if one of the three predetermined relative humidity application ranges rH Figure 2 shown appl-range(n) is selected (i.e., the other one compared to the middle range), then taking into account the correction value for humidity can improve the accuracy of the resulting blood glucose measurement value.

[0107] To this end, determining the concentration of the analyte in step iii) may include determining at least one relative humidity correction value rH appl-range(n) and / or at least one relative humidity correction function rH corr for each case based on one of the relative humidity application ranges rH corr-fct selected in step ii), and taking them into account for the determination of the concentration of the analyte in step iii). By way of example, the relative humidity application ranges rH appl-range(n) may each be independently associated with their own relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct . In Figure 2 , the three relative humidity application ranges (rH appl-range(1)_low with an rH value X1 rH where 0 < X1 threshold(k1) < rH rH , where rH threshold(k1) = 30% rH; rH appl-range(2)_medium with an rH value X2 threshold(k1) where rH rH ≤ X2 threshold(k2) ≤ rH rH , where rH threshold(k1) = 30% rH and rH threshold(k2) = 60% rH; and rH appl-range(3)_high with an rH value X3 threshold(k2) where rH rH < X3 rH , where rH threshold(k2) = 60% rH) are each associated with their own relative humidity correction function rH corr-fct . However, alternatively, some of the relative humidity application ranges rH appl-range(n) may not be associated with a relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct , such that for the relative humidity application range rH appl-range(n)Some of them determine the concentration of the analyte without considering the correction value for relative humidity. The latter case may be applicable, for example, to the second relative humidity range rH appl-range(2)_medium as conceived and given as an example hereinabove in the text.

[0108] In step iii), the relative humidity correction value rH corr and / or the relative humidity correction function rH corr-fc t may further include associating rH corr and / rH corr-fct with a predefined concentration range of the analyte concentration. The predefined concentration range is selected from at least two predefined analyte concentration ranges. As an example, regarding Figure 2 , the first predefined concentration range of the analyte concentration has a concentration value of 0 mg / dl to <120 mg / dl; the second predefined concentration range has a concentration value of 120 mg / dl to 200 mg / dl; and the third predefined concentration range has a concentration value of >200 mg / dl. In this example, the relative humidity correction functions rH corr-fct are each associated with a different one of the three predefined concentration ranges of the analyte concentration. In this scenario, according to Figure 2 , for each of the three concentration ranges, different correction values for relative humidity are considered. However, alternatively, some of the predefined concentration ranges of the analyte concentration may be associated with the relative humidity correction function rH corr-fct such that for some of the predefined concentration ranges of the analyte concentration, the determination of the concentration of the analyte in step iii) is performed without considering the correction value for relative humidity. The latter case may be conceived, for example, for the third predefined concentration range of the analyte concentration having an analyte concentration value of >200 mg / dl, as given as an example hereinabove in the text.

[0109] As a specific example, an estimated value of the local relative humidity of rH estimate = 20% rH may be derived from the color of the hydrochromic indicator region in the image in step ii). Based on the estimated value of the local relative humidity of rH estimate = 20% rH, the first relative humidity range rH appl-range(1)_low (having an rH value X1 rH <rH threshold(k1) where rH rH = 30% rH) may be selected from three pre-determined relative humidity ranges rH threshold(k1) , which are illustrated in appl-range(n) and given as an example in Figure 2 .

[0110] The first relative humidity range rH appl-range(1)_low is further associated withFigure 2 are associated with three predefined concentration ranges of the analyte concentration (having the following concentration values respectively: 0 mg / dl to < 120 mg / dl; 120 mg / dl to 200 mg / dl; and > 200 mg / dl). In this example, the relative humidity correction function rH corr-fct , for including rH appl-range(1)_low of three predetermined relative humidity applicable ranges rH appl-range(n) each is associated with three predefined concentration ranges of the analyte concentration, such that different correction values for relative humidity are considered for each of the three concentration ranges.

[0111] For the first predetermined relative humidity applicable range rH appl-range(1)_low considered in this example, and regarding Figure 2 , if the measured blood glucose concentration value is less than 120 mg / dl, a constant correction is applied to the determination of the concentration of the analyte in step iii). This constant correction at least partially compensates for the positive deviation of the blood glucose measurement value observed at a relative humidity of 15% rH, and when the analyte concentration value is < 120 mg / dl, on average, expressed as Δ concentration, this positive deviation is greater than 10%. For the measured analyte concentration between 120 mg / dl and 200 mg / dl, similarly, a correction is applied to the determination of the concentration of the analyte in step iii), but in this case, the correction linearly decreases from 120 mg / dl to 200 mg / dl. For the measured analyte concentration above 200 mg / dl, the correction value for relative humidity is not applied or not considered respectively.

[0112] Similarly, the third predetermined relative humidity applicable range rH appl-range(3)_high (having an rH value X3 threshold(k2) <X3 rH for rH rH , where rH threshold(k2) = 60% rH) can be considered. This third predetermined relative humidity applicable range is associated with its own relative humidity correction function rH corr-fct , and this third predetermined relative humidity applicable range itself is further associated with Figure 2 the three predefined concentration ranges of the analyte concentration shown. For rH appl-range(3)_high and regarding Figure 2 , similarly, if the measured blood glucose concentration value is less than 120 mg / dl, a constant correction is applied to the determination of the concentration of the analyte in step iii). However, for rH appl-range(3)_high, this constant calibration at least partially compensates for the negative bias in blood glucose measurement values observed at a relative humidity of 85% rH, and when the analyte concentration value is < 120 mg / dl, on average, expressed as Δ concentration, this negative bias is greater than 5%. For the analyte concentration measured between 120 mg / dl and 200 mg / dl, similarly, apply calibration to the determination of the analyte concentration in step iii), where the calibration linearly decreases from 120 mg / dl to 200 mg / dl. For the analyte concentration measured above 200 mg / dl, do not apply or consider the calibration value for relative humidity, respectively.

[0113] List of Reference Signs

[0114] 112 Mobile device

[0115] 114 Camera

[0116] 118 Optical test element (optical test strip; color reference card)

[0117] 120 Reagent test area

[0118] 121 Hydrochromic indicator area

[0119] 124 Image

[0120] 148 Kit

[0121] 149 Processor

Claims

1. A computer-implemented analysis method for determining the concentration of an analyte in a body fluid by using a mobile device having at least one camera, the computer-implemented analysis method comprising: i) Receive at least one image captured by the camera of the mobile device, the image including at least a portion of a reagent test area associated with an optical test element and / or associated with a color reference card, the reagent test area having been applied with a sample of the body fluid, the image further including at least a portion of at least one hydrochromic indicator area associated with the optical test element and / or associated with the color reference card, wherein the hydrochromic indicator area exhibits at least one optically detectable color change at a relative humidity rH at a predetermined threshold level threshold(m) exhibits at least one optically detectable color change; ii) Derive an estimate rH of the local relative humidity from the color of the hydrochromic indicator region in the image estimate ; and based on the estimate rH estimate select one of at least two predetermined applicable ranges of relative humidity rH appl-range(n) ; And iii) Consider the applicable range of relative humidity rH selected in step ii) appl-range(n) , and determine the concentration of the analyte from the color of the reagent test area in the image based on the color formation reaction at the reagent test area of the sample to which the body fluid is applied; where rH threshold(m) and rH estimate each of which is the rH value provided in the form of "%rH", respectively.

2. The method according to claim 1, wherein each of the at least one optically detectable color change occurs substantially completely within at least one narrow interval of the rH value, wherein each of the at least one narrow interval of the rH value is centered on at least one of the predetermined threshold level of relative humidity rH threshold(m) ; specifically, wherein each of the at least one narrow interval of the rH value includes rH values spanning a range of no more than 15% rH.

3. The method according to any one of claims 1 and 2, wherein the at least one hydrochromic indicator region comprises one or more individual hydrochromic indicator regions, each of the one or more individual hydrochromic indicator regions exhibiting at least one optically detectable color change independently of one another at specifically different predetermined threshold levels of relative humidity rH threshold(m) below, and the predetermined threshold levels of relative humidity rH threshold(m) each comprise, in each case, one or more, specifically one rH value selected from 10% rH, 15% rH, 20% rH, 25% rH, 30% rH, 45% rH, 50% rH, 55% rH, 60% rH, 65% rH, 70% rH, 75% rH and 80% rH.

4. The method according to any one of the preceding claims, wherein the at least two predetermined relative humidity application ranges rH appl-range(n) comprise - First relative humidity applicable range rH appl-range(1)_low , which has an rH value X1 where 0 < X1 rH < rH threshold(k) ; and a second relative humidity applicable range rH rH ; and a second relative humidity applicable range rH appl-range(2)_high , which has an rH value X2 where rH threshold(k) ≤ X2 rH ; or rH ; or - At least three predetermined relative humidity ranges of applicability rH appl-range(n) ; Specifically, wherein the at least three predetermined relative humidity application ranges rH appl-range(n) include at least a first relative humidity application range rH appl-range(1)_low which has an rH value X1 of 0 < X1 rH < rH threshold(k1) ; and a second relative humidity application range rH rH which has an rH value X2 of rH appl-range(2)_medium ≤ X2 threshold(k1) ≤ rH rH ≤ rH threshold(k2) ; and a third relative humidity application range rH rH which has an rH value X3 of rH appl-range(3)_high < X3 threshold(k2) < X3 rH ; rH ; wherein X1 rH , X2 rH , X3 rH , rH threshold(k) , rH threshold(k1) and rH threshold(k2) each of which is an rH value provided in the form of "%rH".

5. The method according to the preceding claim, wherein rH threshold(k) is an rH value selected from among 15% rH, 30% rH, 45% rH, 60% rH, and 75% rH; or wherein rH threshold(k1) is an rH value selected from among 15% rH, 20% rH, 25% rH, 30% rH, 35% rH, and 40% rH, and rH threshold(k2) is an rH value selected from among 50% rH, 55% rH, 60% rH, 65% rH, 70% rH, and 75% rH.

6. The method according to any one of the preceding claims, wherein determining the concentration of the analyte in step iii) comprises: Determine at least one relative humidity correction value rH independently of one another based on one of the relative humidity application ranges rH selected in step ii) in each case appl-range(n) and / or at least one relative humidity correction function rH corr ; and perform the determination of the concentration of the analyte taking into account the at least one relative humidity correction value rH corr-fct and / or the at least one relative humidity correction function rH corr . corr-fct ​ 7. The method according to claim 6, wherein one or more of the relative humidity application ranges rH appl-range(n) are associated with their own relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct ; wherein the relative humidity correction value rH appl-range(n) and / or relative humidity correction function rH corr can be selected independently of each other for each relative humidity application range rH corr-fct ; optionally, wherein at least one of the relative humidity application ranges rH appl-range(n) is not associated with a relative humidity correction value rH corr and / or relative humidity correction function rH corr-fct such that for said at least one of the relative humidity application ranges rH appl-range(n) the determination of the concentration of the analyte is made without considering the correction value for relative humidity.

8. The method according to any one of claims 6 and 7, wherein in step iii), the at least one relative humidity correction value rH is considered corr and / or the at least one relative humidity correction function rH corr-fct further comprises associating one or more of the relative humidity correction values rH corr and / or one or more of the relative humidity correction functions rH corr-fct independently of each other with a predefined concentration range of the analyte concentration, the predefined concentration range being selected from at least two predefined analyte concentration ranges.

9. The method according to claim 8, wherein at least one of the predefined concentration ranges of the analyte concentration is not associated with the relative humidity correction value rH corr and / or the relative humidity correction function rH corr-fct , such that for at least one of the predefined concentration ranges of the analyte concentration, the determination of the concentration of the analyte in step iii) is performed without considering the correction value for relative humidity.

10. The method according to any one of the preceding claims, wherein the method further comprises receiving at least one additional estimate rH of the local relative humidity from at least one of the following add-estimate : a) A remote weather service, via a wireless connection with the mobile device; b) An external electronic device including an environmental humidity sensor, via a wireless connection with the mobile device; and c) An environmental humidity sensor located in the mobile device; and wherein step ii) comprises validating or adjusting the estimated value rH of the local relative humidity by considering at least one of the additional estimated values rH add-estimate wherein each of rH estimate and rH estimate is provided in the form of "% rH". add-estimate ​ 11. A mobile device having at least one camera and at least one processor, the mobile device being configured to determine the concentration of an analyte in a body fluid, wherein at least one concentration of the analyte is determined from a color-forming reaction at a reagent test area; and wherein the mobile device is further configured to perform at least steps i) to iii) of the computer-implemented analysis method according to any one of claims 1 to 10.

12. A kit comprising the mobile device according to claim 11 and at least one of an optical test element and a color reference card, the optical test element and / or the color reference card being associated with the reagent test area.

13. A computer program comprising instructions which, when executed by the mobile device according to claim 11, cause the mobile device to implement at least steps i) to iii) of the computer-implemented analysis method according to any one of claims 1 to 10.

14. A computer-readable storage medium comprising instructions which, when executed by the mobile device according to claim 11, cause the mobile device to implement at least steps i) to iii) of the computer-implemented analysis method according to any one of claims 1 to 10.

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