METHODS AND DEVICES FOR PERFORMING AN ANALYTICAL MEASUREMENT

Abstract

A method of performing an analytical measurement based on a color formation reaction in an optical test strip by using a mobile device having a camera, a display and a position sensor. An optical test strip having a test field is provided. The camera captures a first image of the test field before a sample is applied and a second image after the sample is applied. An item of admissibility information, based on one or both of position sensor data and local position data, is determined. Admissibility is indicated when the position of the mobile device is substantially the same for capturing the first and the second image. When admissibility is indicated, an analytical measurement takes place. Further, a computer program, a computer-readable storage medium, a mobile device and a kit are disclosed.

Claims

1. A method of performing an analytical measurement based on a color formation reaction in an optical test strip by using a mobile device having a camera, a display and a position sensor, the method comprising: a) providing a dry optical test strip having a test field; b) using the camera to capture a first image of at least part of the test field without having a sample applied thereto; c) applying a sample of body fluid to the test field; d) using the camera to capture a second image of at least part of the test field having the sample applied thereto; e) determining an item of admissibility information indicating admissibility when the position of the mobile device is substantially the same for capturing the first and the second image, wherein the item of admissibility information is determined based on one or both of position sensor data and local position data, wherein the local position data is or comprises spatial information referring to a position of at least one environmental feature in a field of view of the camera; and f) when the item of admissibility information indicates admissibility, determining an analytical measurement result value by using the first and the second images of the test field.

2. The method according to claim 1, further comprising, when the item of admissibility information indicates inadmissibility, performing one or both of: displaying an error message on the display of the mobile device; and aborting the method of performing an analytical measurement.

3. The method according to claim 1, wherein step e) comprises retrieving first and second items of position information from the position sensor and comparing the first and second items of position information, wherein the first item of position information comprises information on a position of the mobile device when capturing the first image in step b) and the second item of position information comprises information on a position of the mobile device when capturing the second image in step d).

4. The method according to claim 3, wherein the item of admissibility information indicates admissibility when the second item of position information is, at least within a predetermined range of tolerance, identical to the first item of position information and otherwise the item of admissibility information indicates inadmissibility.

5. The method according to claim 1, wherein the camera is a front camera of the mobile device, wherein the camera and the display are both positioned on a front of the mobile device.

6. The method according to claim 1, wherein in steps b) and d) the mobile device is positioned in a fixed position by one or both of: using a holder for the mobile device; and placing the mobile device on a fixed surface.

7. The method according to claim 6, wherein the fixed surface is a surface selected from the group consisting of a level surface, a seating surface, a floor, a shelf board, an inclined or sloped surface, a flat surface and an irregular surface.

8. The method according to claim 1, wherein when capturing the first image in step b), the test field is illuminated by using the display of the mobile device, wherein when capturing the second image in step d), the test field of the optical test strip is illuminated by using the display of the mobile device.

9. The method according to claim 1, wherein the method further comprises providing indications concerning where to locate the optical test strip for capturing the first and/or the second image by using the mobile device.

10. The method according to claim 9, wherein the indication is provided by using the display of the mobile device, wherein the indication concerning where to locate the optical test strip of step h) comprises superposing a live image of the camera on the display of the mobile device with a visual guidance.

11. The method according to claim 1, wherein step d) comprises capturing a plurality of second images, wherein the method comprises monitoring reaction kinetics by using the plurality of second images.

12. A non-transitory computer readable medium having stored thereon executable instructions for performing the method according to claim 1.

13. A mobile device for performing an analytical measurement, comprising: a camera; a display; and a position sensor; wherein the mobile device has a processor with a memory having stored thereon executable instructions for performing the method according to claim 1.

14. A kit for performing an analytical measurement, the kit comprising: the mobile device of claim 13; and an optical test strip having a test field.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0161] The above-mentioned aspects of exemplary embodiments will become more apparent and will be better understood by reference to the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0162] FIG. 1 shows an embodiment of a kit and a mobile device for performing an analytical measurement in a perspective view;

[0163] FIG. 2 shows an embodiment of a mobile device for performing an analytical measurement in a front view;

[0164] FIGS. 3 to 5 show flowcharts of different embodiments of a method of performing an analytical measurement;

[0165] FIG. 6 exemplarily show a diagram of measured reaction kinetics; and

[0166] FIG. 7 shows comparative blood glucose measurements.

DESCRIPTION

[0167] The embodiments described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of this disclosure.

[0168] In FIG. 1, an exemplary embodiment of a kit 110 for performing an analytical measurement is shown in a perspective view. The kit 110 comprises a mobile device 112, such as for example a smart phone, and further at least one optical test strip 114. In the illustrated set-up, the optical test strip 114 is placed in a field of view 116 of a camera 118 of the mobile device 112.

[0169] The mobile device 112, besides the at least one camera 118, comprises at least one display 120, wherein the display 120 may be configured for displaying a live image 122 taken by the camera 118 and/or for displaying information to a user. The mobile device 112 further comprises at least one position sensor 124, such as, for example, a position sensor 124 configured for detecting one or both of a position, e.g., a location, of the mobile device 112 and a change in the position, e.g., the location, of the mobile device 112.

[0170] The optical test strip 114 may comprise at least one substrate 126, such as a flexible, strip shaped substrate. The optical test strip 114 further comprises at least one test field 128 applied to the substrate, the test field 128 comprising at least one test chemical for performing a detection reaction with at least one analyte comprised by a sample 130, specifically by a sample 130 of bodily fluid. The sample may directly or indirectly be applied to the test field 128, such as by applying a droplet of the bodily fluid to the test field 128 and/or, as exemplarily illustrated in FIG. 1, to a spreading aid 132 from which the sample 130 is conducted to the test field 128.

[0171] The display 120 of the mobile device 112, as exemplarily illustrated in FIG. 2, may for example comprise a first area 134, which may be illuminated for illuminating the test field 128 of the optical test strip 114. Additionally or alternatively, the mobile device 112 may comprise at least one illumination source 136, such as an LED or the like, for illuminating the test field 128. Further, the display 120 may comprise a second area 138 for displaying information to the user.

[0172] The mobile device 112 is configured, for example by appropriate programming of a processor 140 of the mobile device 112, for performing at least steps e) and f) of a method of performing an analytical measurement. The method will be described with reference to exemplary embodiments shown in flowcharts illustrated in FIGS. 3, 4 and 5.

[0173] The method of performing an analytical measurement based on a color formation reaction in an optical test strip 114 by using a mobile device 112 having a camera 118, at least one display 120 and a position sensor 124 comprises the following steps, which may specifically be performed in the given order. Still, a different order may also be possible. It may be possible to perform two or more of the method steps fully or partially simultaneously. It may further be possible to perform one, more than one or even all of the method steps once or repeatedly. The method may comprise additional method steps which are not listed. The method steps of the method are the following: [0174] a) (denoted with reference number 142) providing a dry optical test strip 114 having a test field 128; [0175] b) (denoted with reference number 144) capturing at least one first image of at least part of the test field 128 of the dry optical test strip 114 without having a sample 130 applied thereto by using the camera 118; [0176] c) (denoted with reference number 146) applying a sample 130 of bodily fluid to the test field 128 of the optical test strip 114; [0177] d) (denoted with reference number 148) capturing at least one second image of at least part of the test field 128 of the optical test strip 114 having the sample 130 applied thereto by using the camera 118; [0178] e) (denoted with reference number 150) determining at least one item of admissibility information, wherein the item of admissibility information indicates admissibility in case the position of the mobile device 112 is substantially the same for capturing the first and the second image, wherein the item of admissibility information is determined based on one or both of position sensor data and local position data; and [0179] f) (denoted with reference number 152) if the item of admissibility information indicates admissibility, determining an analytical measurement result value by using the first and the second image of the test field 128 of the optical test strip 114.

[0180] Further, as exemplarily illustrated in FIG. 4, the method may comprise a branching point 154. The branching point 154 may indicate a condition query, such as deciding between a first branch 156 and a second branch 158. For example, the condition query may make use of the item of admissibility information. The item of admissibility information may comprise Boolean information, such as “admissible” (“y”) or “inadmissible” (“n”). As an example, the first branch 156 indicates admissibility of determining an analytical measurement result value from the first image and the second image captured by using the camera 118 of the mobile device 112. Thus, the first branch 156 leads to step f), wherein the analytical measurement result value is determined by using the first and the second image of the test field 128 of the optical test strip 114.

[0181] The second branch 158 may indicate inadmissibility and, thus, may lead to step g) (denoted with reference number 160) if the item of admissibility information indicates inadmissibility, performing one or both of: displaying an error message on the display 120 of the mobile device 112; and aborting the method of performing an analytical measurement.

[0182] As illustrated in FIG. 5, step e) 150 may, for example, be performed in parallel to other method steps, such as steps b) 144, c) 146 and d) 148, before determining the analytical measurement result value in step f) 152. Additionally, the method may comprise further steps, such as indicating a user to position the mobile device 112 in a fixed position (denoted with reference number 162), for example as by indicating to place a phone and/or smart phone, on a fixed surface, e.g., on a table. Specifically, performance of step e) may, for example, start with the mobile device, e.g., the smartphone, being placed on any flat support, for example on a table. Thus, the position sensor 124 of the mobile device 112, e.g., a smartphone sensor, may start monitoring movements of the mobile device, e.g., of the smartphone. Further the method may comprise a step (denoted with reference number 164) of requesting an analytical measurement, such as a blood glucose measurement, and a step (denoted with reference number 166) of displaying a result of the measurement. As an example, the result of the measurement displayed may be a range indication, indicating a range within which the analytical measurement has been detected. Additionally or alternatively, the result of the measurement displayed may be the analytical measurement result value. In particular, for example, the result of the measurement may be displayed on the display 120 of the mobile device 112. Further steps, such as informing a user that the phone must be on rest before a measurement sequence starts, though not illustrated in the Figures, may be possible.

[0183] In FIG. 6, an exemplary diagram of reaction kinetics is illustrated. For this experiment, the mobile phone 112 was kept in a fixed position while the test strip 114 was kept in a freehand manner in the front camera's field of view upon application of a sample to the test field. The x-axis in FIG. 6 shows the consecutive frames (measurement data points) taken; the y-axis shows the measured counts in the red channel. The number of measurement data points taken during the reaction is taking place may depend on the user handling, such as on the handling of the optical test strip 114 and/or the mobile device 112 by the user, in case where image capturing is triggered automatically. As an example, the automatically triggered image capturing may be or may comprise capturing a quantity of N images per second, wherein 1≤N≤15, specifically 3≤N≤12, more specifically 5≤N≤10.

[0184] Despite some noise in the signal being visible due to the freehand positioning of the test strip in the camera's field of view, the wetting induced drop in intensity can be clearly seen in the beginning. In particular, in the diagram illustrated in FIG. 6, the wetting induced change, e.g., a wetting drop 167, may be or may comprise a change of more than 25% in the measured counts in the red channel as illustrated on the y-axis. As an example, in FIG. 6, the wetting induced change, such as the wetting drop 167, may be visible in a first time frame 169, e.g., from frames 10 to 16, wherein the reaction kinetic used for determining the concentration of the analyte 171 may be visible in a second time frame 172, e.g., from frames 16 to 30. Between frames 0 and 10 the measured counts in the red channel may vary less than 25%, specifically less than 15%. In particular, monitoring the wetting-induced change based on the plurality of second images may serve as safeguard to exclude too short or overly long reaction times of the sample with the reagent system. Furthermore, monitoring the wetting-induced change can also be used to determine the starting point of the chemical reaction and thus measure reaction times. The reaction time can then be considered in the determination of the analyte concentration.

[0185] In FIG. 7, measurement results are shown which demonstrate the effect of controlling the local positions for capturing the blank image and the final image. For these experiments, blood glucose measurements were performed using an optical test strip 114 and a sample 130. Two different setups were used: In a first setup, denoted by reference number 168, for the blank images or first images and the final images or second images were taken at identical local positions. Specifically, in the first setup 168, the camera 118 was positioned in an identical location for the first and second images and the optical test strip 114 was positioned in an identical location for the first and second images. In a second setup, denoted by reference number 170, the blank images or first images were taken at a common first local position, and the final images or second images were taken at a common second local position, wherein the second local position differed from the first local position. Specifically, in the second setup 170, the position of the camera 118 was changed between the taking of the first and second images and the position of the optical test strip 114 was also changed between the taking of the first and second images. In each setup, 10 measurements were performed, wherein for the blank images a fresh optical test strip 114 was used (no sample applied), whereas for the final images an optical test strip 114 was used 3 days after sample application for demonstration purposes (the test field of this strip had constant optical properties different from a fresh optical test strip).

[0186] On the horizontal axis, the two different setups 168, 170 are shown in FIG. 7. On the vertical axis, the determined analytical measurement result is shown, in this case a blood glucose concentration c in mg/dl. The results are shown as box plots for both setups 168, 170. As can be seen, a significant difference occurs between the correct or controlled setup 168 and the uncontrolled setup 170. The difference is supposed to be mainly due to differing illumination conditions in the first and second local positions. The difference clearly shows the benefit of this disclosure since taking the first and second images at similar local positions can provide for increased measurement performance, e.g., in terms of reproducibility and/or accuracy.

[0187] While exemplary embodiments have been disclosed hereinabove, the present invention is not limited to the disclosed embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of this disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

LIST OF REFERENCE NUMBERS

[0188] 110 Kit [0189] 112 mobile device [0190] 114 optical test strip [0191] 116 field of view of the camera [0192] 118 Camera [0193] 120 Display [0194] 122 live image taken by the camera [0195] 124 position sensor [0196] 126 Substrate [0197] 128 test field [0198] 130 Sample [0199] 132 spreading aid [0200] 134 first area [0201] 136 illumination source [0202] 138 second area [0203] 140 Processor [0204] 142 step a) [0205] 144 step b) [0206] 146 step c) [0207] 148 step d) [0208] 150 step e) [0209] 152 step f) [0210] 154 branching point [0211] 156 first branch [0212] 158 second branch [0213] 160 step g) [0214] 162 indicating a user to position the mobile device in a fixed position [0215] 164 requesting an analytical measurement [0216] 166 displaying the analytical measurement result value [0217] 167 wetting drop [0218] 168 first setup: blank image and final image taken at identical local positions [0219] 169 first time frame [0220] 170 second setup: blank image and final image taken at different local positions [0221] 171 reaction kinetic used for determining the concentration of the analyte [0222] 172 second time frame