Method for evaluating the suitability of lighting conditions for detecting analytes in a sample using a camera of a mobile device

Abstract

The present invention discloses a method (110) for evaluating the suitability of lighting conditions for detecting an analyte in a sample using a camera (112) of a mobile device (114). The method comprises the following steps: a) (117) capturing at least one first image of at least one test strip (116); b) (122) capturing at least one second image of the test strip (116); c) (124) comparing the first image and the second image captured in steps a) (117) and b) (122) to determine a difference in lighting conditions between the first image and the second image; and d) (126) deriving at least one item of suitability information based on the comparison in step c) (124), wherein the suitability information comprises information regarding the suitability of the lighting conditions for detecting the analyte.

Description

Technical Field

[0001] The present application relates to a method for evaluating the suitability of lighting conditions for detecting an analyte in a sample using a camera of a mobile device and a detection method for detecting an analyte in a sample by using a camera of a mobile device. The invention further relates to a computer program with program means for executing the method according to the invention. In addition, the invention relates to a mobile device. The method, computer program and mobile device according to the invention can be used in medical diagnosis in order to qualitatively or quantitatively detect one or more analytes in one or more body fluids. However, other fields of application of the invention are also possible. Background Art

[0002] In the field of medical diagnostics, in many cases, one or more analytes must be detected 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 typically present in these body fluids. If necessary, appropriate treatment can be selected depending on the concentration and / or presence of the analyte.

[0003] In general, the apparatus and methods known to the skilled person utilize test elements comprising one or more test chemicals that can perform one or more detectable detection reactions, such as optically detectable detection reactions, in the presence of an analyte to be detected. Regarding these test chemicals, reference may be made to, for example, the following literature by J. Hoenes et al.: The Technology Behind Glucose Meters: Test Strips, Diabetes Technology & Therapeutics, Vol. 10, Supplement 1, 2008, S-10 to S-26. Other types of test chemicals are also possible and can be used to perform the present invention.

[0004] In analytical measurements, in particular analytical measurements based on color forming reactions, a technical challenge is to evaluate the color change caused by the detection reaction. In addition to the use of dedicated analytical equipment such as handheld blood glucose meters, the use of general electronic devices such as smart phones and portable computers has become increasingly popular in recent years. WO 2012 / 131386 A1 discloses a test device for performing an assay, the test device comprising: a container containing a reagent, the reagent reacting to an applied test sample by forming a color or pattern change; a portable device, such as a mobile phone or a laptop computer, comprising a processor and an image capture device, wherein the processor is configured to process data captured by the image capture device and output a test result of the applied test sample.

[0005] WO 2014 / 025415A2 discloses a method and apparatus for performing color-based reaction testing on biological materials. The method includes capturing and interpreting digital images of unexposed and later exposed instruments in an automated calibration environment. The instrument includes: a unique identification (UID) label; a reference color bar (RCB) that provides a standard color sample for image color calibration; and several test-specific sequences of chemical test plates (CTPs). The method further includes: locating the instrument in the image; extracting the UID; extracting the RCB; and locating multiple CTPs in each image. The method further reduces image noise in the CTP and automatically calibrates the image based on light measurements performed on the RCB. The method further determines the test results by comparing the colors of the CTP image with the colors in the Manufacturer Interpretation Color Chart (MICC). The method displays these results in a graphical or quantitative mode.

[0006] EP 1801568 A1 discloses a test strip and method for measuring the concentration of an analyte in a biological fluid sample. The method involves positioning a camera on the test strip so as to graphically detect a color indicator and a reference color area. A measured value of the relative position between the camera and the strip is determined and compared with an expected value area. The camera is moved to reduce the deflection relative to the strip during the deflection between the measured value and the expected value. The image area assigned to the indicator is located in the color image detected by the camera. The analyte concentration in the sample is determined by the comparison value.

[0007] EP 1963828 B1 discloses a method for measuring the concentration of at least one analyte contained in a biological fluid sample, a) wherein a test strip is prepared, the test strip having at least one test point, at least one time indicator and at least one reference color range including the color white and / or a color scale; b) wherein the fluid sample is brought into contact with the test point and the time indicator; c) wherein the color indicator is arranged on the test point in accordance with the concentration of the analyte; d) wherein the color of the time indicator changes in accordance with the duration of contact of the fluid with the test point and is independent of the concentration of the at least one analyte; e) wherein a camera is positioned on the test strip; f) wherein at least one measurement value of the relative position between the camera and the test strip is determined and compared with a nominal value range; g) wherein, if there is a difference between the measured value and the nominal value range, the camera is moved relative to the test strip in order to reduce the difference, and f) and g) are repeated; h) wherein a color image is recorded using the camera, on which at least the color indicator, the time indicator and the reference color range are imaged; j) wherein image areas associated with the color indicator, the time indicator and the reference color range are located in the color image and the color values ​​of these image areas are determined; k) wherein based on the color value determined for the time indicator, with the aid of a predetermined reference value, the duration between the contact of the fluid sample with the test point and the recording of the color image is determined; and l) wherein based on the color value determined for the color indicator and the reference color range and based on the duration, with the aid of a predetermined comparison value, the analyte concentration in the sample is determined.

[0008] The reliability and accuracy of analytical measurements performed using mobile computing devices generally depend on a number of technical factors. In particular, there are a large number of mobile devices with cameras on the market, all of which have different technical and optical properties that must be taken into account when performing analytical measurements. WO 2007 / 079843 A2 describes a method for measuring the concentration of an analyte contained in a biological fluid sample. In the method, a test strip is provided, which includes at least one test point and at least one reference color portion covering the color white and / or a color scale. The fluid sample is brought into contact with the test point and a color indicator is set on the test point depending on the concentration of the analyte. A camera is placed on the test strip. At least one measurement value of the relative position between the camera and the test strip is detected and compared with a set value range. If the measurement value deviates from the set value range, the camera is moved relative to the test strip to reduce the deviation. A color image is detected with the aid of the camera, on which at least the color indicator and the reference color portion are represented. An image area assigned to the color indicator and the color matching portion is located and a color value of the image area is determined. Based on the color value, the analyte concentration in the sample is determined with the aid of a predefined comparison value. EP 3 108 244 A1 and WO 2015 / 120819 A1 describe a test strip module comprising a housing, a test strip in the housing, and a position anchor extending downward through a mating surface to a face of a mobile computing device. The position anchor has a shape that matches a feature on a face of the mobile computing device.

[0009] US 2015 / 233898 A1 describes a test strip module including a housing, a test strip in the housing, and a position anchor extending downward through a mating surface to a face of a mobile computing device. The position anchor has a shape that matches a feature on a face of the mobile computing device.

[0010] Despite the advantages of using mobile computing devices to perform analytical measurements, there are still several technical challenges. In particular, the reliability and accuracy of the measurements need to be enhanced and ensured. When using a mobile phone's camera, the reliability and accuracy of the analytical measurements may depend to a large extent on the lighting conditions during the capture of the image of the test strip used for the analytical measurement. In particular, ambient light may have a significant impact on the lighting conditions, for example, due to the presence of various illumination devices in different specific locations and / or depending on the location where the image is captured and whether the image is captured during the day or at night. In particular, ambient light may interfere with the evaluation of the color formed on the reagent area of ​​the test strip.

[0011] Purpose of the Invention

[0012] Therefore, it is desirable to provide methods and devices that can solve the above-mentioned technical challenges of analytical measurement using mobile devices such as consumer electronic mobile devices, in particular multi-functional mobile devices that are not dedicated to analytical measurement (such as smart phones or tablet computers). In particular, methods and devices that ensure the reliability and accuracy of measurements should be proposed. Summary of the invention

[0013] The problem is solved by a method for assessing the suitability of lighting conditions for detecting an analyte in a sample using a camera of a mobile device, a detection method for detecting an analyte in a sample by using a camera of a mobile device, a computer program and a mobile device having the features of the independent claims. Advantageous embodiments, which may be realized in isolation or in any combination, are listed in the dependent claims.

[0014] As used below, the terms "having", "including" or "comprising" or any grammatical variations thereof are used in a non-exclusive manner. Thus, these terms may refer to the absence of other features in the entity described in this context in addition to the features introduced by these terms, as well as the presence of one or more other features. As an example, the expressions "A has B", "A includes B" and "A contains B" may all refer to the absence of any other elements in A in addition to B (i.e., A consists only of B), as well as the presence of one or more other elements in entity A in addition to B, such as element C, elements C and D, or even other elements.

[0015] In addition, it should be noted that the terms "at least one", "one or more" or similar expressions indicating that a feature or element may exist once or multiple times are usually used only once when introducing the corresponding feature or element. In the following, in most cases, when referring to the corresponding feature or element, the expression "at least one" or "one or more" is not repeated even though the corresponding feature or element may exist only once or multiple times.

[0016] Furthermore, as used below, the terms "preferably", "more preferably", "particularly", "more particularly", "specifically", "more specifically" or similar terms are used in conjunction with optional features without limiting the alternative possibilities. Therefore, the features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As the skilled person will recognize, the present invention may be implemented 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 manner with other optional or non-optional features of the present invention.

[0017] In a first aspect, a method for evaluating the suitability of lighting conditions for detecting an analyte in a sample using a camera of a mobile device is disclosed. The method comprises the following steps, which, by way of example, may be performed in a given order. However, it should be noted that a different order is also possible. Furthermore, one or more method steps may be performed once or repeatedly. Furthermore, two or more method steps may be performed simultaneously or in a timely overlapping manner. The method may include other method steps not listed.

[0018] The method comprises the following steps:

[0019] a) capturing at least one first image of at least one test strip, wherein the test strip is suitable for detecting an analyte in a sample, the test strip having at least one test zone containing at least one test chemistry for performing an optical detection reaction in the presence of the analyte, wherein during the capturing of the first image, an illumination source of the mobile device is turned off;

[0020] b) capturing at least one second image of the test strip, wherein during the capturing of the second image, an illumination source of the mobile device is turned on;

[0021] c) comparing the first image and the second image captured in steps a) and b) to determine a difference in lighting conditions between the first image and the second image; and

[0022] d) deriving at least one item of suitability information based on the comparison in step c), wherein the suitability information comprises information about the suitability of the illumination conditions for the detection of the analyte.

[0023] As used herein, the term "mobile device" is a broad term and is to be given the ordinary and customary meaning to persons of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to (but is not limited to) a mobile electronic device, and more specifically to a mobile communication device such as a cellular phone or a smart phone. In addition or alternatively, as will be further outlined in detail below, a mobile device may also refer to a tablet computer or another type of portable computer having at least one camera.

[0024] As used herein, the term "test strip" is a broad term and will be given the common 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. In particular, the test strip may have a test zone that includes at least one test chemistry for detecting at least one analyte. As an example, the test strip may include at least one substrate such as at least one carrier, wherein at least one test zone is applied thereto or integrated therein. As an example, at least one carrier may be strip-shaped, so that the test element becomes 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, containing the same or different test chemicals in the test zones. The test strip may have at least one sample applied thereto.

[0025] As further used herein, the term "test zone" is a broad term and will be given the ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to (but is not limited to) a coherent amount of a test chemistry, such as a zone (e.g., a circular zone, a polygonal zone, or a rectangular zone) having one or more material layers, wherein the test chemistry is contained in at least one layer of the test zone. Other layers may be present that provide specific optical properties such as reflective properties, provide scattering properties to scatter the sample, or provide separation properties to, for example, separate particulate components (such as cellular components) of the sample.

[0026] As used herein, the term "test chemical" is a broad term and will be given the common and customary meaning for those of ordinary skill in the art, and is not limited to a special or custom meaning. The term may specifically refer to (but not limited to) a compound or compounds, such as a mixture of compounds suitable for performing a detection reaction in the presence of an analyte, wherein the detection reaction can be detected by specific means such as optics. The detection reaction may specifically be analyte-specific. In the present case, the test chemical may specifically be an optical test chemical, such as a color-changing test chemical, which changes color when an analyte is present. The color change may specifically depend on the amount of the analyte present in the sample. As an example, the test chemical may include at least one enzyme, such as glucose oxidase and / or glucose dehydrogenase. In addition, other components may be present, such as one or more dyes, mediators, etc. Test chemicals are generally known to technicians, and reference may be made to J. Hönes et al.: Diabetes Technology and Therapeutics, Vol. 10, Supplement 1, 2008, pp. 10-26. However, other test chemicals are also feasible.

[0027] As used herein, the term "analyte" is a broad term and is to be given the ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customized meaning. The term may specifically refer to (but is not limited to) one or more specific compounds and / or other parameters to be detected and / or measured. As an example, at least one analyte may be a compound involved in metabolism, such as one or more of glucose, cholesterol, or triglycerides. In addition or alternatively, other types of analytes or parameters may be determined, such as pH.

[0028] As used herein, the term "detecting an analyte in a sample" is a broad term and will be given the ordinary and customary meaning to those of ordinary skill in the art and is not limited to a special or customary meaning. The term may specifically refer to (but is not limited to) quantitatively and / or qualitatively determining at least one analyte in any sample. For example, a sample may include a body fluid (such as blood, tissue fluid, urine, saliva or other types of body fluids). As an example, the result of the analytical measurement can be the concentration of the analyte and / or the presence or absence of the analyte to be determined. In particular, as an example, the analytical measurement can be a blood glucose measurement, so the analytical measurement can obtain, for example, a blood glucose concentration.

[0029] The term "suitability" may refer to (but is not limited to) the properties of an element or device for performing one or more predetermined functions and the appropriateness of environmental conditions for ensuring the reliability and accuracy of the analyte in the detection sample. Therefore, the term refers to one or both of the properties of the device and the environmental conditions. Suitability can be defined and / or quantified by determining whether a predetermined requirement is met. As an example, the predetermined requirement (e.g., at least one threshold) can be derived from an experiment, or derived from a boundary condition determined, for example, by the accuracy to be achieved. The term "suitability information" may refer to (but is not limited to) an indication or information about suitability, particularly under current conditions of the suitability of the illumination conditions for the purpose of performing analytical measurements. As an example, a suitability information item may be Boolean or digital information, such as indicating "suitable" or "unsuitable" / "unsuitable". However, in addition or alternatively, suitability information may include quantitative results, such as suitability. For example, suitability information may include information about the adequacy of the light intensity of an illumination source originating from a mobile device for illuminating a test strip. Specifically, suitability information may include information regarding the sufficiency of light intensity originating from an illumination source of a mobile device for illuminating a test strip relative to and / or compared to ambient light intensity and / or ambient light conditions.

[0030] As used herein, the term "assessing the suitability of lighting conditions" refers to testing and / or determining and / or assessing and / or estimating lighting conditions. As used herein, the term "lighting conditions" refers to both image capture conditions, in particular ambient light conditions and the light intensity provided by the illumination source of the mobile device. In addition, the term "lighting conditions" refers to reflective conditions, in particular the reflective properties of the test strip, for example due to the material of the test strip. The term "ambient light" or "ambient light conditions" refers to light from an available natural or artificial light source, which illuminates the test strip independently of the illumination provided by the illumination source of the mobile device. Ambient light can be generated and / or provided by an artificial light source, such as indoor lighting (e.g., a lamp) and / or a natural light source, such as the sun, the moon, starlight, lightning. The lighting conditions may depend on the time, in particular the daytime or the nighttime. The lighting conditions may depend on the location, in particular whether the image is acquired outdoors or indoors, or on the geographical location. In particular, for outdoor measurements, the lighting conditions may depend on weather conditions. For indoor measurements, the lighting conditions may depend on the room lighting, which may vary depending on activities such as home, supermarket, theater, etc.

[0031] As used herein, the term "camera" is a broad term and will be given the ordinary and customary meaning for ordinary technicians in the field, and is not limited to a special or customized meaning. The term may specifically refer to (but 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 information. As an example, the camera may include at least one camera chip such as at least one CCD chip and / or at least one CMOS chip configured to record an image. For example, the camera may be a color camera, as will be described in detail below, which includes at least three color pixels. The camera may be a color CMOS camera. For example, the camera may include black and white pixels and color pixels. The color pixels and black and white pixels may be combined inside the camera. The camera may include at least one color camera and at least one black and white camera, such as a black and white CMOS. The camera may include at least one black and white CMOS chip. The camera may generally include a one-dimensional or two-dimensional array of image sensors, such as pixels. As an example, the camera may include at least 10 pixels in at least one dimension, such as at least 10 pixels in each dimension. However, it should be noted that other cameras are also feasible. The camera may be a camera of a mobile communication device. The invention should be particularly applicable to cameras commonly used in mobile applications, such as notebook computers, tablet computers or in particular cellular phones such as smartphones. Thus, in particular, the camera can be part of a mobile device, which, in addition to at least one camera, also includes one or more data processing devices such as one or more data processors. However, other cameras are also feasible. In addition to at least one camera chip or imaging chip, the camera may also include other elements, such as one or more optical elements, for example, one or more lenses. As an example, the camera may be a fixed-focus camera, which has at least one lens that is fixedly adjusted relative to the camera. However, alternatively, the camera may also include one or more variable lenses that can be adjusted automatically or manually.

[0032] The camera may in particular be a color camera. Thus, color information, such as color values ​​for three colors R, G, B, may be provided or generated, such as for each pixel. A larger number of color values ​​is also feasible, such as four colors per pixel. Color cameras are generally known to the skilled person. Thus, as an example, each pixel of a camera chip may have three or more different color sensors, such as color recording pixels, such as one pixel for red (R), one pixel for green (G), and one pixel for blue (B). For each pixel, such as for R, G, B, a value, such as a digital value in the range of 0 to 255, may be recorded by the pixel depending on the intensity of the respective color. As an example, instead of using a color triplet such as R, G, B, a quadruplet such as C, M, Y, K or RGGB, BGGR, RGBG, GRGB, RGGB, etc. may be used. The color sensitivity of the pixel may be generated by a color filter, such as a color filter array (e.g. by at least one Bayer filter) or by an appropriate intrinsic sensitivity of the sensor element used in the camera pixel. These techniques are generally known to the skilled person.

[0033] As used herein, but not limited to, the term "image" may specifically relate to data recorded using a camera, such as multiple electronic readings from an imaging device, such as pixels of a camera chip. Thus, the image itself may include pixels, the pixels of the image being related to the pixels of the camera chip. Thus, when referring to a "pixel", either reference is made to a unit of image information generated by a single pixel of a camera chip, or directly to a single pixel of a camera chip. The image may include raw pixel data. For example, an image may include data in RGGB space, monochrome data from one of an R pixel, a G pixel, or a B pixel, a Bayer pattern image, etc. An image may include evaluated pixel data, such as a full-color image or an RGB image. The raw pixel data may be evaluated, for example, by using a demosaicing algorithm and / or a filtering algorithm. These techniques are generally known to the skilled person.

[0034] The term "capturing at least one image" refers to one or more of imaging, image recording, image acquisition, image capture. The term "capturing at least one image" may include capturing a single image and / or multiple images such as a sequence of images. Capturing of at least one image may be initiated by a user action or may be automatically initiated, for example, upon automatic detection of the presence of at least one object 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.

[0035] As used herein, the term "irradiation source of a mobile device" refers to any light source of the mobile device. The term "irradiation source" refers to at least one device adapted to generate light for irradiating an object. As used herein, the term "light" generally refers to electromagnetic radiation in one or more of the visible spectral range, the ultraviolet spectral range and the infrared spectral range. The term "visible spectral range" generally refers to the spectral range of 380 nm to 780 nm. Preferably, the light used in the present invention is light in the visible spectral range. The illumination source may include at least one light emitting diode integrated in the mobile device. In particular, the illumination source may be a backlight of the mobile device, in particular a mobile phone. The mobile device may include additional illumination devices, such as at least one illumination source for illuminating a display, and / or the display may be designed as an additional illumination source itself.

[0036] The illumination source may have two states, namely an on state in which it generates a light beam for illuminating the test strip and an off state in which the light source is off. As used herein, the term "on" refers to activating and / or turning on the illumination source to illuminate the test strip. The term "off" refers to the illumination source being in an off state or being actively turned off. As outlined above, in step a), a first image is captured in which the illumination source of the mobile device is turned off. This allows the capture of an image that contains only the light intensity of the ambient light source and is independent of the illumination provided by the illumination source of the mobile device. In step b), the illumination source is turned on, making it possible to determine a second image containing the illumination intensity based on both the ambient light and the illumination of the illumination source of the mobile device.

[0037] The illumination source may include at least one light emitting diode (LED) integrated into the mobile device. The illumination source may include at least one white light LED. The white light LED may be controlled using short current pulses so that the white light LED may be adapted to generate a bright flash. The illumination source may be adapted to illuminate the test strip at all times during the capture of the image. The flash duration of the white light LED may require hundreds of milliseconds compared to an electronic flash. This may allow the illumination source to illuminate the test strip at all times during the capture of the image in the flash mode of the LED. Alternatively, the LED may be adapted to permanently illuminate the test strip in a non-flash mode.

[0038] The illumination source may be adapted to be brighter than bright ambient light. The illumination source may be the substantially dominant light source when the image is captured in step b) of the test strip. The term "substantially dominant" means that the illumination source exceeds the illumination of the ambient light, where low illumination from the ambient light is possible. The illumination of a flash generated by a white light LED used in a mobile device may be 80 to 300 lux at an object distance of 1 m. Thus, the illumination of a flash generated by a white light LED may be 8000 to 30000 lux at an object distance of 0.1 m. For comparison, full daylight may have 10752 lux, a cloudy day may have 1075 lux, a very dark day may have 107 lux, and dusk may have 10.8 lux, see https: / / www.noao.edu / education / QLTkit / ACTIVITY_Documents / Safety / LightLevels_outdoor+indoor.pdf. The illumination source may be adapted to generate at least one light beam for illuminating the test strip having a light intensity higher than that of the ambient light. The illumination source may generate an illumination with a light intensity that exceeds the light intensity of the ambient light by a factor of two, preferably 10, and more preferably 100.

[0039] Step c) comprises comparing the first image and the second image captured in steps a) and b) to determine the difference in lighting conditions between the first image and the second image. As outlined above, each pixel of the camera chip may have three or more different color sensors, such as color recording pixels, such as one pixel for red (R), one pixel for green (G), and one pixel for blue (B). Each of the color sensors and / or color recording pixels may be adapted to generate a single signal or multiple sensor signals in response to illumination. The sensor signal may be or may include at least one electrical signal, such as at least one analog electrical signal and / or at least one digital electrical signal. In addition, the raw sensor signal may be used, processed or pre-processed (such as by filtering, etc.), and the sensor signal may also be used. The camera may be adapted to capture the first image and the second image in steps a) and b) in at least one color channel, in particular in at least one color channel selected from the group consisting of an R channel, a G channel, and a B channel. The camera may be adapted to capture the first image and the second image in each color channel in steps a) and b). As used herein, the term "color channel" refers to color recording pixels of a camera chip for the same color. The camera and / or the processor (in particular the processor of the mobile device) may be adapted to determine, for at least one color channel, at least one first intensity distribution from the first image and at least one second intensity distribution from the second image. Preferably, a first intensity distribution and a second intensity distribution may be determined for each color channel. For at least one color channel, the camera and / or the processor (in particular the processor of the mobile device) may be adapted to determine, from the corresponding first intensity distribution, a first intensity spectrum of the corresponding color channel and from the corresponding second intensity distribution, a second intensity spectrum of the corresponding color channel. As used herein, the term "intensity spectrum" refers to an intensity distribution as a function of wavelength. The term "comparing a first image and a second image" refers to comparing a first intensity distribution and a second intensity distribution of at least one color channel and / or comparing a first intensity spectrum and a second intensity spectrum of at least one color channel. The comparison may include at least one mathematical operation, such as subtracting a corresponding sensor signal generated by a color recording pixel of one color channel and / or subtracting an intensity distribution of one color channel and / or subtracting an intensity spectrum of one color channel, and / or dividing by a corresponding sensor signal of one color channel and / or dividing by an intensity distribution of one color channel and / or dividing by an intensity spectrum of one color channel. For example, the comparison may include determining a difference between a first intensity distribution and a second intensity distribution of at least one color channel. Specifically, for the R channel, the G channel, and the B channel, the difference Δ may be determined by the following formula:

[0040] Δ color = I color LEDON – Icolor LEDOFF ,

[0041] where color = R, G, B, where Δcolor is the difference in the corresponding color channels, I color LEDON is the intensity distribution of the second image of the corresponding color channel, and I color LEDOFF is the intensity distribution of the first image of the corresponding color channel. Additionally or alternatively, the comparison may include determining a quotient by dividing the first intensity distribution and the second intensity distribution and / or by dividing by a multiple and / or by dividing by a linear combination of the first intensity distribution and the second intensity distribution of at least one color channel. Specifically, for the R channel, the G channel, and the B channel, the quotient may be determined by the following formula:

[0042] Q color = I color LEDON / I color LEDOFF ,

[0043] Where color = R, G, B, where Q color is the quotient in the corresponding color channel, I color LEDON is the intensity distribution of the second image of the corresponding color channel, and I color LEDOFFis the intensity distribution of the first image of the corresponding color channel. The camera and / or the processor (in particular the processor of the mobile device) may be adapted to perform the specified operation, preferably by using at least one data processing device, and more preferably by using at least one processor and / or at least one application specific integrated circuit. Thus, as an example, the mobile device may include at least one data processing device having a software code stored thereon, the software code comprising a plurality of computer commands. The mobile device may provide one or more hardware elements for performing one or more specified operations, and / or may provide one or more processors with software for performing one or more specified operations running thereon. The term "difference" may refer to a deviation of the first image and the second image, in particular a deviation in the intensity spectrum. In particular, the term "difference" refers to a deviation that is higher than a statistical fluctuation. The illumination source of the mobile device may have a known or predetermined spectral component. The term "spectral component" refers to an intensity spectrum of the illumination generated by the illumination source. In particular, for each of the R channel, the G channel, and the B channel, at least one distribution of light intensity as a function of wavelength may be known or predetermined. In particular, the emission spectrum of the white light LED may be known or may be determined empirically. The spectral composition may be stored in a table or lookup table and may be determined, for example, empirically and, as an example, may be stored in at least one data storage device of the mobile device, for example by software, in particular by an application downloaded from an application store or the like. In general, the illuminated test strip may absorb light within a specific wavelength range, while light that is not absorbed is reflected and captured by the camera. Therefore, the spectral characteristics or composition of the light illuminating the test strip may directly affect the resulting RGB values ​​of the captured image. Since the spectral composition of the illumination source is known or predetermined, it is possible to determine the amount of light intensity originating from the illumination source used to illuminate the test strip. The mobile device may include at least one processor, which may be adapted to compare the first image and the second image.

[0044] The first image and the second image may be captured before applying the sample. Additionally or alternatively, the method may include at least one sample application step, wherein in the sample application step, the sample may be applied to the test strip. Specifically, the sample may be applied to the test strip before steps a) and / or b).

[0045] Step d) comprises deriving at least one item of suitability information based on the comparison in step c). Derivation of suitability information in step d) may comprise comparing the difference in illumination conditions determined in step c) with at least one threshold value. Suitability information may be set to indicate suitability of illumination conditions for analyte detection only when the difference in illumination conditions between the second image and the first image is at least equal to the threshold value. The threshold value may depend on ambient light conditions. For example, a user and / or a processor may be adapted to adjust and / or select a threshold value based on ambient light conditions. The threshold value may be stored in a table or a lookup table and may be determined, for example, empirically and, as an example, may be stored in at least one data storage device of a mobile device, for example, by software, in particular by an application downloaded from an application store, etc. For example, suitability information may be set to indicate suitability of illumination conditions for subsequent analyte detection only when at least 70% of the light intensity for illuminating the test strip comes from the illumination source. For example, suitability information may be set to indicate suitability of illumination conditions for subsequent analyte detection only when at least 80% of the light intensity for illuminating the test strip comes from the illumination source. Other threshold values ​​are also possible. For example, suitability information may be set to indicate suitability of the lighting conditions for subsequent analyte detection only if 90% of the light intensity used to illuminate the test strip comes from the illumination source.

[0046] If the composition of the ambient light substantially corresponds to the expected composition of the illumination generated by the illumination source, the light conditions may be indicated as suitable even in the case of a bright ambient light source. The term "composition" refers to the color composition of the illumination, in particular the composition of the intensity distribution of the corresponding color channel. The term "expected composition" predetermines the spectral composition.

[0047] The term "substantially corresponds to" refers to a condition in which the composition of the ambient light corresponds to the expected composition of the illumination generated by the illumination source, with a tolerance of ±30% or less, preferably a tolerance of ±20% or less, most preferably a tolerance of ±10% or less. If I is satisfied R Ambient / I G Ambient / I B Ambient ≤ε (I R LEDON / I G LEDON / I B LEDON ), it can indicate that the light conditions are suitable, where I R Ambient ,I G Ambient ,I B Ambientis the intensity distribution of the corresponding color channel illuminated by the ambient light, I R LEDON ,I G LEDON ,I B LEDON is the intensity distribution of the corresponding color channel of the illumination generated by the illumination source, and ε≤0.3, preferably ε≤0.2, most preferably ε≤0.1.

[0048] The method may further comprise checking and / or assessing whether the illumination source provides sufficient illumination intensity. Checking and / or assessing whether the illumination source is configured to provide sufficient illumination may use at least one threshold method. The adequacy of the illumination intensity may depend on the surface properties of the test strip and / or the ambient light conditions. In particular, in the case of a test strip with highly reflective properties, a lower light intensity may be sufficient compared to dark or low reflective properties. Furthermore, in bright ambient light conditions, for example due to sunlight, a higher intensity may be required compared to shielded ambient light conditions.

[0049] In another aspect of the present invention, a detection method for detecting an analyte in a sample by using a camera of a mobile device is disclosed. The method comprises the following steps, which may be performed in a given order as an example. However, it should be noted that a different order is possible. Furthermore, one or more method steps may be performed once or repeatedly. Furthermore, two or more method steps may be performed simultaneously or in a timely overlapping manner. The method may include other method steps not listed. The method comprises the following steps:

[0050] i) assessing lighting conditions by using the method for assessing suitability of lighting conditions according to one of the preceding embodiments;

[0051] ii) If the suitability information regarding the suitability of the lighting conditions indicates that the lighting conditions are suitable for performing analyte detection, performing the following steps:

[0052] A) providing at least one test strip for detecting an analyte in a sample, the test strip having at least one test zone containing at least one test chemistry for performing an optical detection reaction in the presence of the analyte;

[0053] B) applying at least one sample to a test area of ​​a test strip;

[0054] C) capturing at least one image of the test area by using a camera, wherein during said capturing, an illumination source of the mobile device is turned on; and

[0055] D) Determine the analyte concentration in the sample based on the image captured in step C).

[0056] With regard to embodiments and definitions of the detection method, reference is made to the description of the method for assessing the suitability of lighting conditions described above and in further detail below. In particular, with regard to method step i), reference may be made to the description of the method for assessing the suitability of lighting conditions described above.

[0057] The determination of the analyte concentration may include optical detection. As used herein, the term "optical detection" refers to the detection of a reaction using an optical test chemistry, such as a color-changing test chemistry that changes color when an analyte is present. The color change may specifically depend on the amount of analyte present in the sample. Step D) may include analyzing the color of a spot on a test zone of a test strip, the spot at least partially containing the sample. Techniques for determining analytes by optical detection, in particular the color of spots on a test zone, are generally known to the skilled person. In order to evaluate at least one image and derive at least one analytical information thereof, several algorithms generally known to those skilled in the art in the field of analysis, such as in the field of blood glucose monitoring, may be used. Thus, as an example, the color of a test element, such as the color of at least one test zone with at least one test chemistry, may be evaluated. As an example, when evaluating an image, a region of interest may be defined within the image of the test element, such as within the test zone of the test element, and a color analysis, such as a statistical analysis, may be performed. As an example, a rectangular, square, polygonal, elliptical or circular region of interest may be defined within a portion of the image that is identified as a test zone. Subsequently, a statistical analysis may be performed on the colors of the pixels within the region of interest. As an example, one or more color coordinates of a pixel may be derived, and a statistical analysis of the color coordinates may be performed over the region of interest. As an example, the distribution center of at least one color coordinate may be determined. As used herein, the term "color coordinate" is a broad term and will be given the common and customary meaning for 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 not limited to) coordinates of any color coordinate system for describing a color using coordinates. Technicians generally know several color coordinate systems, and these color coordinate systems may also be used in the context of the present invention. Therefore, as an example, a colorimetric coordinate system or a coordinate system based on human perception may be used, such as the CIE 1964 color space, the Munsell color system, or other coordinate systems such as R, G, B, L, a, B.

[0058] Thus, as an example, in order to derive analytical information from an image, a predetermined or determinable relationship between at least one color coordinate of a test element, such as a test zone, may be monitored. As outlined above, a statistical analysis may be performed on a test element or a portion thereof, such as a test zone containing at least one test chemistry and / or a region of interest within a test zone containing at least one test chemistry. Thus, as an example, at least one test zone within an image of a test element may be preferably identified automatically (e.g., by pattern recognition and / or other algorithms described in the following examples). Likewise, one or more regions of interest may be defined within a partial image of a test zone. Above the region of interest, color coordinates may be determined, for example, again by using one or more histograms (e.g., again determining a blue coordinate and / or other color coordinates). The statistical analysis may include fitting one or more fitting curves (as described above) to at least one histogram, thereby, for example, determining the center of a peak. Thus, a color forming reaction may be monitored by using one or more images, wherein, for one or more images, the center of a peak may be determined by using a statistical analysis, thereby determining a color shift within at least one coordinate. Once the color forming reaction is complete or has reached a predetermined or determinable endpoint, as is generally known to the skilled person, for example from blood glucose monitoring, a shift in at least one color coordinate or endpoint color coordinate may be determined and the shift may be converted, for example, to the concentration of the analyte in the sample by using a predetermined or determinable correlation between the color coordinate and the concentration. As an example, the correlation, the transfer function, the conversion table or the lookup table may be determined, for example, empirically and, as an example, may be stored in at least one data storage device of the mobile device, for example by software, in particular by an application downloaded from an application store, etc.

[0059] In case the assessment of the lighting conditions in step i) is not set to indicate that the lighting conditions are suitable, the mobile device may be adapted to abort and / or prevent detection of the analyte in the sample. Additionally or alternatively, in case the assessment of the lighting conditions in step i) is not set to indicate that the lighting conditions are suitable, the mobile device may be adapted to generate at least one warning. Additionally or alternatively, in case the assessment of the lighting conditions in step i) is not set to indicate that the lighting conditions are suitable, the mobile device may be adapted to repeat step i). Additionally or alternatively, in case the assessment of the lighting conditions in step i) is not set to indicate that the lighting conditions are suitable, the mobile device may be adapted to generate at least one prompt to the user to change the ambient light conditions, such as moving to a different location and / or turning off interfering light sources.

[0060] After step D), the lighting conditions may be evaluated by using the method for evaluating the suitability of lighting conditions according to the present invention. If the suitability information about the suitability of the lighting conditions indicates that the lighting conditions are not suitable for performing analyte detection, the determined analyte concentration may be rejected. The mobile device may be adapted to generate a warning to the user, such as a visual warning on a display of the mobile device and / or at least one acoustic warning.

[0061] Step C) may include providing a visual indication for the user to position the test strip relative to the camera so that the test area is at least partially located in the target area. As used herein, the term "target area" refers to a predetermined or pre-specified area in which the test area of ​​the test strip may be assumed to be located during the capture of the image. A visual indication such as a visual guide may be provided to the user before the image is captured. The visual indication may include at least one instruction, such as a text message and / or a graphical instruction. For example, the visual indication may include a visualization of a test strip or a portion of a test strip, such as an outline and / or an outline of the test strip. The visual indication may include an outline of the test strip or a reference area on the test strip (e.g., a frame corresponding to the shape of the test strip), which is superimposed on the display of the mobile device, providing a visual guide for positioning the camera relative to the test strip. In the event that it is determined that the clarity criteria and / or the spatial criteria can be met, in particular in the event that the outline of the test strip of the visual indication is determined to be overlaid on the test strip, the capture of at least one image may be automatically initiated. The visual indication may depend on the test strip used. For example, visual indications such as the outline and / or contour of the test strip may be determined empirically and / or may be stored in at least one look-up table and / or in at least one data storage device of the mobile device, for example by software, in particular at least one application downloaded from an application store, etc. Additionally or alternatively, audio guidance or other types of guidance may be given.

[0062] As will be further outlined in detail below, the method for assessing the suitability of lighting conditions and the detection method may be fully or partially computer-implemented, in particular implemented on a computer of a mobile device, such as a processor of the mobile device. Thus, in particular, the method may comprise the use of at least one processor and software instructions for executing at least method steps c) and d) of the method for assessing the suitability of lighting conditions and / or method step d) of the detection method. In particular, these methods may be fully or partially implemented as a so-called application (e.g. for Android or iOS) and may be downloaded from an application store as an example. The software instructions (in particular the application) may further provide user instructions, for example via one or more of a display, audio instructions or other instructions, in order to support the method for assessing the suitability of lighting conditions and / or the method steps of the detection method. Therein, as described above, method steps a) and b) may also be fully or partially computer-implemented, for example by automatically taking a first image and a second image of at least one test strip using a camera once the test strip is within the field of view of the camera and / or within a certain range within the field of view. In particular, the processor for executing the method for assessing the suitability of lighting conditions and / or the detection method may be part of the mobile device.

[0063] As outlined above, the mobile device may specifically be a mobile computer and / or a mobile communication device. Thus, specifically, the mobile device may be selected from the group consisting of: a mobile communication device, in particular a smartphone; a portable computer, in particular a notebook; a tablet computer.

[0064] As mentioned above, further method steps may be computer-implemented or computer-assisted, in particular by a processor of the mobile device.

[0065] In another aspect of the present invention, a computer program is disclosed, the computer program comprising computer executable instructions for executing the method for evaluating the suitability of lighting conditions according to any one of the embodiments described herein. In particular, the computer executable instructions may be suitable for executing one or more of the method steps a), b), c) and d). In particular, the program is executed on a computer or a computer network, in particular on a processor of a mobile device having at least one camera.

[0066] Thus, generally speaking, a computer program is disclosed and proposed herein, the computer program comprising computer executable instructions for executing the method for assessing the suitability of lighting conditions according to the present invention in one or more embodiments attached herein when the program is executed on a computer or a computer network. In particular, the computer program may be stored on a computer-readable data carrier. Thus, in particular, one, more than one or even all method steps as indicated above may be performed by using a computer or a computer network, preferably by using a computer program. In particular, the computer may be fully or partially integrated into a mobile device, and the computer program may be specifically embodied as a software application. However, alternatively, at least a part of the computer may also be located outside the mobile device.

[0067] The present invention further discloses and proposes a data carrier having a data structure stored thereon, which, after being loaded into a computer or a computer network, such as into a working memory or a main memory of the computer or the computer network, can execute a method for evaluating the suitability of lighting conditions according to one or more embodiments disclosed herein, specifically one or more of the method steps mentioned above.

[0068] The present invention further discloses and proposes a computer program product having program code means stored on a machine-readable carrier, so that when the program is executed on a computer or a computer network, the method for evaluating the suitability of lighting conditions according to one or more embodiments disclosed herein is performed. As used herein, a computer program product refers to a program that is a tradable product. The product can generally exist in any format (such as a paper format) or on a computer-readable data carrier. In particular, the computer program product can be distributed on a data network.

[0069] Finally, this document discloses and proposes a modulated data signal containing instructions that can be read by a computer system or a computer network for executing a method for evaluating the suitability of lighting conditions according to one or more embodiments disclosed herein, specifically for executing one or more steps of the method for evaluating the suitability of lighting conditions as described above.

[0070] Specifically, this article further discloses the following:

[0071] - a computer or a computer network comprising at least one processor, wherein the processor is adapted to perform the method for assessing the suitability of lighting conditions according to one of the embodiments described in this specification,

[0072] - a computer-loadable data structure adapted to perform, when the data structure is executed on a computer, a method for assessing the suitability of lighting conditions according to one of the embodiments described in this specification,

[0073] - a computer program, wherein the computer program is adapted to perform, when the program is executed on a computer, a method for assessing the suitability of lighting conditions according to one of the embodiments described in this specification,

[0074] - a computer program comprising program means for executing the method for assessing the suitability of lighting conditions according to one of the embodiments described in the present description when the program means is executed on a computer or a computer network,

[0075] - a computer program comprising program means according to the preceding embodiment, wherein the program means is stored on a computer-readable storage medium,

[0076] - a storage medium, on which a data structure is stored and wherein the data structure is adapted to, after loading into a main storage device and / or a working storage device of a computer or a computer network, execute a method for assessing the suitability of lighting conditions according to one of the embodiments described in the present description, and

[0077] - A computer program product having program code means, wherein the program code means can be stored or stored on a storage medium for executing the method for assessing the suitability of lighting conditions according to one of the embodiments described in the present description when the program code means are executed on a computer or a computer network.

[0078] In another aspect of the present invention, a computer program is disclosed, the computer program comprising computer executable instructions for performing a detection method according to any one of the embodiments described herein. In particular, the computer executable instructions may be suitable for performing one or more of the method steps i) and ii). In particular, the program is executed on a computer or a computer network, in particular on a processor of a mobile device having at least one camera.

[0079] Therefore, in general, a computer program is further disclosed and proposed herein, which includes computer executable instructions for executing the detection method according to the present invention in one or more embodiments attached herein when the program is executed on a computer or a computer network. In particular, the computer program can be stored on a computer-readable data carrier. Therefore, in particular, one, more than one or even all method steps as indicated above can be performed by using a computer or a computer network, preferably by using a computer program. In particular, the computer can be fully or partially integrated into a mobile device, and the computer program can be specifically embodied as a software application. However, alternatively, at least a portion of the computer can also be located outside the mobile device.

[0080] This document further discloses and proposes a data carrier having a data structure stored thereon, which, after being loaded into a computer or a computer network, such as into a working memory or a main memory of the computer or the computer network, can execute a detection method according to one or more embodiments disclosed herein, specifically one or more of the method steps mentioned above.

[0081] The present invention further discloses and proposes a computer program product having program code means stored on a machine-readable carrier, so that when the program is executed on a computer or a computer network, a detection method according to one or more embodiments disclosed herein is performed. As used herein, a computer program product refers to a program that is a tradable product. The product can generally exist in any format (such as paper format) or on a computer-readable data carrier. In particular, the computer program product can be distributed on a data network.

[0082] Finally, this article discloses and proposes a modulated data signal, which contains instructions that can be read by a computer system or a computer network for executing a detection method according to one or more embodiments disclosed in this article, specifically for executing one or more steps of the detection method as described above.

[0083] Specifically, this article further discloses the following:

[0084] - a computer or a computer network comprising at least one processor, wherein the processor is adapted to perform the detection method according to one of the embodiments described in this specification,

[0085] - a computer loadable data structure adapted to perform, when the data structure is executed on a computer, a detection method according to one of the embodiments described in this specification,

[0086] - a computer program, wherein the computer program is adapted to perform a detection method according to one of the embodiments described in this specification when the program is executed on a computer,

[0087] - a computer program comprising program means for executing the detection method according to one of the embodiments described in this specification when the program means is executed on a computer or a computer network,

[0088] - a computer program comprising program means according to the preceding embodiment, wherein the program means is stored on a computer-readable storage medium,

[0089] - a storage medium, on which a data structure is stored and wherein the data structure is adapted to, after loading into a main storage device and / or a working storage device of a computer or a computer network, perform a detection method according to one of the embodiments described in the present description, and

[0090] - A computer program product having program code means, wherein the program code means can be stored or stored on a storage medium for executing the detection method according to one of the embodiments described in the present description when the program code means is executed on a computer or a computer network.

[0091] In another aspect of the present invention, a mobile device for performing analytical measurements is disclosed. The mobile device comprises

[0092] - At least one camera;

[0093] - at least one radiation source; and

[0094] - at least one processor comprising program means for executing the method for assessing the suitability of lighting conditions according to one of the preceding embodiments.

[0095] For most of the terms used herein and possible definitions, reference is made to the above description of the methods.

[0096] The processor may further include a program device for executing the detection method according to any one of the aforementioned embodiments. The mobile device may be a mobile communication device.

[0097] Compared to known methods and devices for analytical measurement, the method and device according to the present invention can provide a large number of advantages. Compared to processes known in the art, the present invention can improve the reliability and accuracy of the process of performing analytical measurement. In particular, compared to known applications or computer programs, the present invention can improve the reliability and accuracy of application programs (e.g., applications), including computer executable instructions for performing analytical measurement. In particular, the present invention can allow ensuring robust image capture conditions that are independent of ambient light conditions and for different mobile devices. In particular, this can be ensured by avoiding and / or significantly reducing the influence of ambient light.

[0098] In summary and without excluding further possible embodiments, the following embodiments may be envisaged:

[0099] Embodiment 1: A method for evaluating the suitability of lighting conditions for detecting an analyte in a sample using a camera of a mobile device, the method comprising the following steps:

[0100] a) capturing at least one first image of at least one test strip, wherein the test strip is suitable for detecting an analyte in a sample, the test strip having at least one test zone containing at least one test chemistry for performing an optical detection reaction in the presence of the analyte, wherein during the capturing of the first image, an illumination source of the mobile device is turned off;

[0101] b) capturing at least one second image of the test strip, wherein during the capturing of the second image, an illumination source of the mobile device is turned on;

[0102] c) comparing the first image and the second image captured in steps a) and b) to determine a difference in lighting conditions between the first image and the second image; and

[0103] d) deriving at least one item of suitability information based on the comparison in step c), wherein the suitability information comprises information about the suitability of the illumination conditions for the detection of the analyte.

[0104] Embodiment 2: A method according to the preceding embodiment, wherein the illumination source has a known or predetermined spectral composition.

[0105] Embodiment 3: The method according to any one of the preceding embodiments, wherein the illumination source is adapted to be brighter than bright ambient light.

[0106] Embodiment 4: The method according to any of the preceding embodiments, wherein the first image and the second image are captured before applying the sample.

[0107] Embodiment 5: The method according to any one of the preceding embodiments, wherein the method comprises at least one sample application step, wherein in the sample application step, a sample is applied to the test strip, wherein the sample is applied to the test strip before steps a) and / or b).

[0108] Embodiment 6: The method according to any one of the preceding embodiments, wherein deriving the suitability information in step d) comprises comparing the difference in the lighting conditions determined in step c) with at least one threshold value.

[0109] Embodiment 7: The method according to the preceding embodiment, wherein the suitability information is set to indicate the suitability of the illumination condition for analyte detection only if the difference in illumination condition between the second image and the first image is at least equal to the threshold.

[0110] Embodiment 8: The method according to any of the preceding embodiments, wherein the suitability information is configured to indicate suitability of the illumination conditions for subsequent analyte detection only if at least 80% of the light intensity used to illuminate the test strip comes from the illumination source.

[0111] Embodiment 9: The method according to any one of the preceding embodiments, wherein the method further comprises checking and / or evaluating whether the illumination source provides sufficient illumination intensity.

[0112] Embodiment 10: The method according to any one of the preceding embodiments, wherein the camera is the camera of a mobile communication device.

[0113] Embodiment 11: The method according to any one of the preceding embodiments, wherein the illumination source of the mobile device comprises at least one light emitting diode integrated in the mobile device.

[0114] Embodiment 12: A detection method for detecting an analyte in a sample by using a camera of a mobile device, the method comprising:

[0115] i) assessing lighting conditions by using the method for assessing suitability of lighting conditions according to any one of the preceding embodiments;

[0116] ii) If the suitability information regarding the suitability of the lighting conditions indicates that the lighting conditions are suitable for performing analyte detection, performing the following steps:

[0117] A) providing at least one test strip for detecting an analyte in a sample, the test strip having at least one test zone containing at least one test chemistry for performing an optical detection reaction in the presence of the analyte;

[0118] B) applying at least one sample to said test area of ​​said test strip;

[0119] C) capturing at least one image of the test area by using a camera, wherein during said capturing, an illumination source of the mobile device is turned on; and

[0120] D) Determine the analyte concentration in the sample based on the image captured in step C).

[0121] Embodiment 13: The detection method according to the preceding embodiments, wherein step D) comprises analyzing the color of a spot on the test area of ​​the test strip, wherein the spot at least partially contains the sample.

[0122] Embodiment 14: The detection method according to any one of the two preceding embodiments, wherein step C) comprises providing a visual indication for the user to position the test strip relative to the camera so that the test area is at least partially located in a target area.

[0123] Embodiment 15: A detection method according to any one of the two preceding embodiments, wherein after step D), the lighting conditions are evaluated by using the method for evaluating the suitability of lighting conditions according to any one of the preceding embodiments, wherein if the suitability information about the suitability of the lighting conditions indicates that the lighting conditions are not suitable for analyte detection, the determined analyte concentration is rejected.

[0124] Embodiment 16: A computer program comprising program means for executing a method for assessing the suitability of lighting conditions according to one of the preceding embodiments, the program means relating to a method for assessing the suitability of lighting conditions when the computer program is executed on a computer or on a computer network, in particular on a processor of the mobile device.

[0125] Embodiment 17: A computer program comprising program means for executing a detection method according to one of the preceding embodiments, the program means relating to a detection method when the computer program is executed on a computer or on a computer network, in particular on a processor of the mobile device.

[0126] Embodiment 18: A mobile device, comprising:

[0127] - At least one camera;

[0128] - at least one radiation source; and

[0129] - at least one processor comprising program means for executing the method for assessing the suitability of lighting conditions according to one of the preceding embodiments, the program means relating to a method for assessing the suitability of lighting conditions.

[0130] Embodiment 19: The mobile device according to the preceding embodiment, wherein the processor further comprises a program device for executing the detection method according to any one of the preceding claims, wherein the program device relates to a detection method.

[0131] Embodiment 20: The mobile device according to any one of the above two embodiments, wherein the mobile device is a mobile communication device. BRIEF DESCRIPTION OF THE DRAWINGS

[0132] Further optional features and embodiments will be disclosed in more detail in the subsequent description of the embodiments, preferably in conjunction with the dependent claims. Wherein, as will be appreciated by those skilled in the art, each optional feature can be implemented in an isolated manner and in any arbitrary feasible combination. The scope of the present invention is not limited by the preferred embodiments. Embodiments are schematically depicted in the accompanying drawings. Wherein, the same reference numerals in these figures refer to the same or functionally comparable elements.

[0133] In the attached figure:

[0134] FIG1 shows a flow chart of a method for evaluating the suitability of illumination conditions and a method for detecting an analyte;

[0135] FIG2 shows a perspective view of an embodiment of a mobile device for performing a method for assessing suitability of lighting conditions; and

[0136] 3A to 3G show experimental results of the relative spectral power distribution of a standard illuminant and the effect of ambient light on camera images. DETAILED DESCRIPTION

[0137] 1 shows a flow chart of a method 110 for evaluating the suitability of lighting conditions for detecting an analyte in a sample using a camera 112 of a mobile device 114 and a method for detecting an analyte 115. The method 110 for evaluating suitability includes the following steps:

[0138] a) capturing (reference numeral 117) at least one first image of at least one test strip 116, wherein the test strip 116 is suitable for detecting an analyte in a sample, the test strip 116 having at least one test zone 118 containing at least one test chemistry for performing an optical detection reaction in the presence of the analyte, wherein during the capturing of the first image, the illumination source 120 of the mobile device 114 is switched off;

[0139] b) (indicated by reference numeral 122 ) capturing at least one second image of the test strip 116 , wherein during the capturing of the second image, the illumination source 120 of the mobile device 114 is switched on;

[0140] c) (reference numeral 124) comparing the first image and the second image captured in steps a) 117 and b) 122 to determine differences in lighting conditions between the first image and the second image; and

[0141] d) (reference numeral 126 ) deriving at least one item of suitability information based on the comparison in step c) 124 , wherein the suitability information comprises information about the suitability of the illumination conditions for the detection of the analyte.

[0142] In FIG. 2 , a perspective view of a mobile device 114 for performing the method 110 for assessing the suitability of lighting conditions is shown. The mobile device 114 may be a mobile electronic device, more specifically a mobile communication device such as a cellular phone or a smart phone. In addition or alternatively, the mobile device 114 may also refer to a tablet computer or another type of portable computer having at least one camera. Furthermore, at least one test strip 116 is shown. The test strip 118 has a test zone 118 containing at least one test chemistry for detecting at least one analyte. As an example, the test strip 116 may include at least one substrate such as at least one carrier, wherein at least one test zone 118 is applied thereto or integrated therein.

[0143] The mobile device 114 includes at least one camera 112. The camera 112 may include at least one camera chip (not shown here), such as at least one CCD chip and / or at least one CMOS chip configured to record images. The camera 112 may generally include a one-dimensional or two-dimensional array of image sensors, such as pixels. The camera 112 may be a camera of a mobile communication device. The camera 112 may specifically be a color camera. The camera 112 may be adapted to generate color values ​​of at least three colors, for example, red (R), green (G), blue (B). As an example, each pixel of the camera chip may have three or more different color sensors, such as color recording pixels, such as one pixel for R, one pixel for G, and one pixel for B.

[0144] The method 110 for evaluating the suitability of lighting conditions may include determining the effect of ambient light on image capture using a camera 112 of a mobile device 114. For example, suitability information may include information about the adequacy of light intensity originating from an illumination source 120 of a mobile device 114 for illuminating a test strip 116. In particular, suitability information may include information about the adequacy of light intensity originating from an illumination source 120 of a mobile device 114 for illuminating a test strip 116 relative to and / or compared to ambient light intensity and / or ambient light conditions. Ambient light may be generated and / or provided by artificial light sources, such as indoor lighting (e.g., lamps), and / or natural light sources, such as the sun, the moon, starlight, lightning. Lighting conditions may depend on time, in particular daytime or nighttime. Lighting conditions may depend on location, in particular whether the image is acquired outdoors or indoors, or on a geographic location. In particular, for outdoor measurements, lighting conditions may depend on weather conditions. For indoor measurements, lighting conditions may depend on room lighting, which may vary depending on activities such as a home, a supermarket, a theater, etc.

[0145] The illumination source 120 may include at least one light emitting diode integrated in the mobile device 114. In particular, the illumination source 120 may be a backlight of the mobile device 114, in particular a mobile phone. The mobile device 114 may include further illumination devices, such as at least one illumination source illuminating at least one display 128, and / or the display 128 may be designed as a further illumination source itself.

[0146] The illumination source 120 may have two states, namely an on state in which it generates a light beam for illuminating the test strip 116 and an off state in which the light source 120 is off. As outlined above, in step a) 117, a first image is captured in which the illumination source 120 of the mobile device 114 is off. This may allow an image to be captured that contains only the light intensity of the ambient light source and is independent of the illumination provided by the illumination source 120 of the mobile device 114. In step b) 122, the illumination source 120 is turned on, making it possible to determine a second image containing the illumination intensity based on both the ambient light and the illumination of the illumination source 120 of the mobile device 114.

[0147] The light emitting diode integrated in the mobile device 114 may include at least one white light LED. The white light LED may be controlled using short current pulses so that the white light LED may be adapted to generate a bright flash. The illumination source 120 may be adapted to illuminate the test strip 116 at all times during the capture of the image. The flash duration of the white light LED may require hundreds of milliseconds compared to an electronic flash. This may allow the illumination source 120 to illuminate the test strip 116 at all times during the capture of the image in the flash mode of the LED. Alternatively, the LED may be adapted to permanently illuminate the test strip in a non-flash mode, wherein the LED is adapted to continuously generate at least one light beam for illuminating the test strip 116.

[0148] The illumination source 120 may be adapted to be brighter than bright ambient light. The illumination source 120 may be the substantially dominant light source when capturing an image in step b) 122 of the test strip 116. The illuminance of a flash generated by a white light LED used in a mobile device may be 80 to 300 lux at an object distance of 1 m. Thus, the illuminance of a flash generated by a white light LED may be 8000 to 30000 lux at an object distance of 0.1 m. For comparison, full daylight may have 10752 lux, a cloudy day may have 1075 lux, a very dark day may have 107 lux, and dusk may have 10.8 lux, see https: / / www.noao.edu / education / QLTkit / ACTIVITY_Documents / Safety / LightLevels_outdoor+indoor.pdf. Illumination source 120 may be adapted to generate at least one light beam 130 for illuminating test strip 116, the at least one light beam having a light intensity higher than that of ambient light. Light beam 130 generated by illumination source 120 may have a light intensity that exceeds that of ambient light by a factor of two, preferably 10, and more preferably 100.

[0149] Step c) 124 comprises comparing the first image and the second image captured in steps a) 117 and b) 122, thereby determining the difference in lighting conditions between the first image and the second image. As outlined above, each pixel of the camera chip may have three or more different color sensors, such as color recording pixels, such as one pixel for red (R), one pixel for green (G), and one pixel for blue (B). For example, the camera 112 may include at least one Bayer sensor. The camera chip may be adapted to generate at least one sensor signal for each of the R channel, the G channel, and the B channel. The camera chip may be adapted to determine the intensity spectrum of the corresponding R channel, the G channel, and the B channel. The camera 112 may be adapted to capture the first image and the second image in steps a) 117 and b) 122 in at least one color channel, in particular in at least one color channel selected from the group consisting of the R channel, the G channel, and the B channel. The camera 112 may be adapted to capture a first image and a second image in each color channel in steps a) 117 and b) 122. The mobile device 114 includes at least one processor 132. The camera 112 and / or the processor 132 may be adapted to determine, for at least one of the color channels, at least one first intensity distribution from the first image and at least one second intensity distribution from the second image. Preferably, the first intensity distribution and the second intensity distribution may be determined for each color channel. For at least one color channel, the camera 112 and / or the processor 132 may be adapted to determine a first intensity spectrum of the corresponding color channel from the corresponding first intensity distribution, and to determine a second intensity spectrum of the corresponding color channel from the corresponding second intensity distribution. For example, the comparison may include determining a difference between the first intensity distribution and the second intensity distribution of at least one color channel. Specifically, for the R channel, the G channel, and the B channel, the difference Δ may be determined by the following formula:

[0150] Δ color = I color LEDON – I color LEDOFF ,

[0151] Where color = R, G, B, where Δ color is the difference in the corresponding color channel, I color LEDON is the intensity distribution of the second image of the corresponding color channel, and I color LEDOFFis the intensity distribution of the first image of the corresponding color channel. Additionally or alternatively, the comparison may include determining a quotient by dividing the first intensity distribution and the second intensity distribution and / or by dividing by a multiple and / or by dividing by a linear combination of the first intensity distribution and the second intensity distribution of at least one color channel. Specifically, for the R channel, the G channel, and the B channel, the quotient may be determined by the following formula:

[0152] Q color = I color LEDON / I color LEDOFF ,

[0153] Where color = R, G, B, where Q color is the quotient in the corresponding color channel, I color LEDON is the intensity distribution of the second image of the corresponding color channel, and I color LEDOFF is the intensity distribution of the first image for the corresponding color channel. Processor 132 may include a computing device adapted to compare the first image and the second image.

[0154] The illumination source 120 of the mobile device 114 may have a known or predetermined spectral composition. In particular, for each of the R channel, the G channel, and the B channel, at least one distribution of light intensity as a function of wavelength may be known or predetermined. In particular, the emission spectrum of the white light LED may be known or may be determined empirically. The spectral composition may be stored in a table or a lookup table and may be determined, for example, empirically, and may be stored, as an example, in at least one data storage device of the mobile device, for example by software, in particular by an application downloaded from an application store, etc. Since the spectral composition of the illumination source 120 is known or predetermined, it is possible to determine the amount of light intensity originating from the illumination source 120 for illuminating the test strip 116.

[0155] The first image and the second image may be captured before applying the sample. Additionally or alternatively, the method may include at least one sample application step, wherein in the sample application step, the sample may be applied to the test strip 116. Specifically, the sample may be applied to the test strip 116 before steps a) 117 and / or b) 122.

[0156] Step d) 126 comprises deriving at least one item of suitability information based on the comparison in step c) 124. Derivation of suitability information in step d) 126 may comprise comparing the difference in the illumination conditions determined in step c) 124 with at least one threshold value. Suitability information may be set to indicate suitability of the illumination conditions for analyte detection only if the difference in illumination conditions between the second image and the first image is at least equal to the threshold value. The threshold value may depend on ambient light conditions. For example, the user and / or the processor 132 may be adapted to adjust and / or select the threshold value based on ambient light conditions. The threshold value may be stored in a table or a lookup table and may be determined, for example, empirically and, as an example, may be stored in at least one data storage device of the mobile device, for example by software, in particular by an application downloaded from an application store, etc. For example, suitability information may be set to indicate suitability of the illumination conditions for subsequent analyte detection only if at least 80% of the light intensity used to illuminate the test strip 116 comes from the illumination source 120. For example, suitability information may be set to indicate suitability of illumination conditions for subsequent analyte detection only if 90% of the light intensity used to illuminate test strip 116 comes from illumination source 120 .

[0157] FIG3A shows the relative power distribution of CIE standard illuminants A, B, C from 380 nm to 780 nm, see https: / / en.wikipedia.org / wiki / Standard_illuminant. FIG3B shows the intensity I of the determined RGB signal as a function of the wavelength λ(nm) for a 100 mg / dl blood sample irradiated with standard illuminant A. FIG3C shows the intensity I of the determined RGB signal as a function of the wavelength λ(nm) for a 100 mg / dl blood sample irradiated with standard illuminant B. FIG3D shows the intensity I of the determined RGB signal as a function of the wavelength λ(nm) for a 100 mg / dl blood sample irradiated with standard illuminant C. It can be observed that the intensity of the determined RGB signal as a function of the wavelength changes depending on the irradiation of the corresponding light source A, B or C. FIG3E shows the intensity I of the determined RGB signal as a function of the wavelength λ (nm) for a 100 mg / dl blood sample, where the sample is illuminated with 10% of the light intensity from the standard illuminant A and 90% of the light intensity from the illumination source 120, which in this case is the light emitting diode of a Samsung Galaxy® J7 smartphone. It can be seen that the intensity of the determined RGB signal as a function of wavelength is independent of the illumination of the corresponding illuminant. The illumination from the illumination source 120 determines the illumination conditions.

[0158] 1 , the detection method 115 includes step i) 134, wherein the illumination condition is evaluated by using a method for evaluating the suitability of the illumination condition. The detection method 115 includes step ii) 136, wherein, if the suitability information about the suitability of the illumination condition indicates that the illumination condition is suitable for performing analyte detection, the following steps are performed:

[0159] A) (indicated by reference numeral 138) providing at least one test strip 116 for detecting an analyte in a sample, the test strip 116 having at least one test zone 118 containing at least one test chemistry for performing an optical detection reaction in the presence of the analyte;

[0160] B) (indicated by reference numeral 140) applying at least one sample to the test area 118 of the test strip 116;

[0161] C) (indicated by reference numeral 142) capturing at least one image of the test area 118 by using the camera 112, wherein during said capturing, the illumination source 120 of the mobile device is turned on; and

[0162] D) (indicated by reference numeral 144) determining the analyte concentration in the sample based on the image captured in step C).

[0163] Step C) 142 may include providing a visual indication for the user to position the test strip 116 relative to the camera 112 so that the test area 118 is at least partially located in the target area. Visual indications such as visual guides may be provided to the user before the image is captured. The visual indication may include at least one instruction, such as a text message and / or a graphical instruction. For example, the visual indication may include a visualization of the test strip 116 or a portion of the test strip 116, such as an outline and / or an outline of the test strip 116. The visual indication may include an outline of the test strip 116 or a reference area on the test strip 116 (e.g., a frame corresponding to the shape of the test strip 116), which is superimposed on the display 128 of the mobile device 114, providing a visual guide for positioning the camera 112 relative to the test strip 116.

[0164] In case the evaluation of the lighting conditions in step i) 134 is not set to indicate that the lighting conditions are suitable, the mobile device 114 may be adapted to suspend and / or prevent detection of the analyte in the sample. Additionally or alternatively, in case the evaluation of the lighting conditions in step i) 134 is not set to indicate that the lighting conditions are suitable, the mobile device 114 may be adapted to generate at least one warning. Additionally or alternatively, in case the evaluation of the lighting conditions in step i) 134 is not set to indicate that the lighting conditions are suitable, the mobile device 114 may be adapted to repeat step i) 134. Additionally or alternatively, in case the evaluation of the lighting conditions in step i) is not set to indicate that the lighting conditions are suitable, the mobile device 114 may be adapted to generate at least one prompt to the user to change the ambient light conditions, such as moving to a different location and / or turning off interfering light sources.

[0165] After step D) 144, the lighting conditions may be evaluated by using the method 110 for evaluating suitability of lighting conditions as described above. If the suitability information regarding the suitability of the lighting conditions indicates that the lighting conditions are not suitable for performing analyte detection, the determined analyte concentration may be rejected. If the suitability information regarding the suitability of the lighting conditions indicates that the lighting conditions are not suitable during analyte detection, the mobile device 114 may be adapted to generate at least one error message. The mobile device 114 may be adapted to generate a warning to the user, such as a visual warning on the display 128 of the mobile device 114 and / or at least one acoustic warning.

[0166] Reference numerals list

[0167] 110 Methods for assessing the suitability of lighting conditions

[0168] 112 Camera

[0169] 114 Mobile devices

[0170] 115 Methods for detecting analytes

[0171] 116 Test Strips

[0172] 117 Step a)

[0173] 118 Test Area

[0174] 120 Irradiation Source

[0175] 122 Step b)

[0176] 124 Step c)

[0177] 126 Step d)

[0178] 128 Display

[0179] 130 Beam

[0180] 132 Processors

[0181] 134 Step i)

[0182] 136 Step ii)

[0183] 138 Step A)

[0184] 140 Step B)

[0185] 142 Step C)

[0186] 144 Step D).

Claims

1. A method (110) for evaluating the suitability of lighting conditions for detecting an analyte in a sample using a camera (112) of a mobile device (114), the method comprising the steps of: a) (117) capturing at least one first image of at least one test strip (116), wherein the test strip (116) is suitable for detecting an analyte in the sample, the test strip (116) having at least one test zone (118), the at least one test zone comprising at least one test chemistry for performing an optical detection reaction in the presence of the analyte, wherein during the capturing of the first image, an illumination source (120) of the mobile device (114) is turned off; b) (122) capturing at least one second image of the test strip (116), wherein during the capturing of the second image, the illumination source (120) of the mobile device (114) is turned on, wherein the illumination source (120) has a known or predetermined spectral composition, wherein the spectral composition is an intensity spectrum of the illumination generated by the illumination source (120); wherein the method comprises at least one sample application step, wherein in the sample application step, a sample is applied to the test strip (116), wherein the sample is applied to the test strip (116) prior to steps a)(117) and / or b)(122); c) (124) comparing the first image and the second image captured in steps a) (117) and b) (122) to determine a difference in lighting conditions between the first image and the second image, wherein the camera (112) is adapted to capture the first image and the second image in steps a) and b) in at least one color channel, wherein the camera (112) and / or the processor (132) of the mobile device (114) is adapted to determine at least one first intensity distribution from the first image and at least one second intensity distribution from the second image for at least one of the color channels, and wherein comparing the first image and the second image is comparing the first intensity distribution and the second intensity distribution for at least one of the color channels, and since the spectral composition of the illumination source (120) is known or predetermined, the amount of light intensity originating from the illumination source (120) for illuminating the test strip (116) can be determined; and d) (126) deriving at least one item of suitability information based on the comparison in step c) (124), wherein the suitability information includes information about the suitability of the illumination conditions for analyte detection; The suitability information is configured to indicate suitability of the illumination conditions for subsequent analyte detection only if at least 70% of the light intensity used to illuminate the test strip (116) comes from the illumination source (120).

2. The method (110) of claim 1, wherein the illumination source (120) is adapted to be brighter than bright ambient light.

3. The method (110) of any one of claims 1-2, wherein the first image and the second image are captured before applying the sample.

4. The method (110) according to any one of claims 1-2, wherein deriving the suitability information in step d)(126) comprises comparing the difference in the lighting conditions determined in step c)(124) with at least one threshold value.

5. A method (110) according to any one of claims 1-2, wherein the suitability information is configured to indicate the suitability of the illumination conditions for subsequent analyte detection only when at least 80% of the light intensity used to illuminate the test strip (116) comes from the illumination source (120).

6. The method (110) according to any one of claims 1-2, wherein the method (110) further comprises checking and / or evaluating whether the illumination source (120) provides sufficient illumination intensity.

7. The method (110) according to any of claims 1-2, wherein the illumination source (120) of the mobile device (114) comprises at least one light emitting diode integrated in the mobile device (114).

8. A detection method for detecting an analyte in a sample by using a camera (112) of a mobile device (114), the method comprising: i) assessing lighting conditions by using a method according to any one of the preceding claims; ii) if the suitability information about the suitability of the illumination conditions indicates that the illumination conditions are suitable for performing analyte detection, performing the following steps: A) providing at least one test strip (116) for detecting an analyte in said sample, said test strip (116) having at least one test zone (118), said at least one test zone comprising at least one test chemistry for performing an optical detection reaction in the presence of said analyte; B) applying at least one sample to the test area (118) of the test strip (116); C) capturing at least one image of the test area (118) by using the camera (112), wherein during the capturing, an illumination source (120) of the mobile device (114) is turned on; and D) determining the concentration of the analyte in the sample based on the image captured in step C).

9. A computer program product comprising a computer program which, when executed on a processor of a mobile device, performs the method (110) according to any one of claims 1-7.

10. A computer program product comprising a computer program, which, when executed on a processor of a mobile device, performs the detection method according to claim 8.

11. A mobile device (114), comprising: - at least one camera (112); - at least one radiation source (120); as well as - at least one processor (132), said at least one processor comprising program means for executing the method (110) according to any one of claims 1-7.

12. The mobile device (114) according to claim 11, wherein the processor (132) further comprises program means for executing the detection method according to claim 8.

13. The mobile device (114) according to any of claims 11-12, wherein the mobile device (114) is a mobile communication device.

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