FI126816B - Disposable test strip - Google Patents

Description

Disposable test strip Field of the application

The present application relates to test strips and methods for measuring an analyte from a liquid sample. More particularly the present application relates to an test strip which can be analysed by using a mobile terminal with a camera.

Background A test strip may be used for detecting and measuring an analyte from a liquid sample. In general a test strip contains one or more reagents which react with the analyte of interest to produce a detectable signal. The detectable signal provides information for example about the presence or the concentration of the analyte in the sample.

One example of the reaction used for determining the presence or concentration of an analyte in a sample is a reaction wherein a coloured reaction product is formed. The intensity or the colour of the colour reaction corresponds to the concentration of the analyte in the sample.

To obtain a reliable and accurate result, such as a concentration of the analyte in the sample, specific reading devices are usually used. These devices are in general expensive and can be used only for reading a specific type of test strip, so such devices are not suitable for everyday use and are only sold by specialized dealers. Usually the devices need external electricity and are not suitable for portable use.

The same applies in general to the test strips. The test strips are designed to be used with the corresponding reader devices to provide accurate results. Such specific products are usually also expensive, and as well as the devices, are sold only by specialized dealers. Such products are in general not suitable to be sold in regular stores for occasional use.

There may be variations in the quality of the test strips caused by the manufacturing process, for example because of differences in different batches of reagents or materials, or manufacturing conditions, which may affect to the result obtained with the test strip.

Summary

One embodiment provides a test strip for measuring an analyte from a liquid sample, the test strip comprising -a reaction layer containing reagent arranged to react with the analyte to produce a colour reaction indicating the presence or the concentration of the analyte, and -a reference colour area and a computer-readable code associated with information related to the test strip.

In a further embodiment the test strip comprises a liquid impermeable bottom layer containing the reference colour area and the computer-readable code associated with information related to the test strip. The colour reaction, the reference colour and the computer-readable code are visible at the bottom layer side of the strip.

One embodiment provides a test strip for measuring an analyte from a liquid sample, the test strip comprising -a non-transparent liquid impermeable layer containing at least one liquid-permeable portion defining a measuring area, wherein the at least one liquid-permeable portion is at the outer edge of the measuring area and there is no liquid-permeable portion at the centre of the measuring area, on top of a -a reaction layer, such as a fibrous reaction layer, containing reagent arranged to react with the analyte to produce a colour reaction indicating the presence or the concentration of the analyte. In a further embodiment the reaction layer is on top of a -a liquid impermeable bottom layer containing a reference colour area.

One embodiment provides a computer-executable program code product for determining the presence or the concentration of an analyte on a test strip, which computer-executable program code, when run in a mobile terminal having a camera, is arranged to -obtain a photograph of said test strip, -determine the intensity or the colour of the colour reaction indicating the presence or concentration of the analyte and the intensity or the colour of at least one reference colour in the reference colour area from the photograph, -identify the test strip with the information associated with the computer-read-able code, and to -determine the presence or the concentration of the analyte by using the determined intensity or the colour of the colour reaction and using the intensity or the colour of at least one reference colour in the reference colour area as a standard.

One embodiment provides a method for measuring an analyte from a liquid sample, the method comprising -providing said test strip, -providing a mobile terminal having a camera and a computer-executable-software installed for determining the presence or the concentration of an analyte on a test strip, -applying the liquid sample onto the test strip to obtain a colour reaction indicating the presence or concentration of the analyte, -obtaining a photograph of the colour reaction, the reference colour area and the computer-readable code from the test strip by using the mobile terminal having a camera, and by using the computer-executable program code -determining the intensity or the colour of the colour reaction and the intensity or the colour of at least one reference colour in the reference colour area from the photograph, -identifying the test strip with the information associated with the computer-readable code, and -determining the presence or the concentration of the analyte by using the determined intensity of the colour reaction and the intensity or the colour of at least one reference colour in the reference colour area as a standard.

The main embodiments are characterized in the independent claims. Various embodiments are disclosed in the dependent claims. The features recited in dependent claims and in the description are mutually freely combinable unless otherwise explicitly stated.

The feature that the test strip contains a reference colour area provides an effect that the reference colour is always present on the test strip. Further, the reference colour may be adjusted according to the current test and the reagents used therein. For example any variations in the colour reaction caused by the variations in the used reagents or materials in the manufacture of the test strip may be taken into account and the reference colour may be adjusted to provide accurate results.

The feature that the test strip contains a computer-readable code associated with information related to or identifying the test strip provides an effect that the test may be recognized, for example by the mobile device used for analysing the test strip. Further, extra information may be included from a networked resource or from other resource, such as information relating to the batch or lot number of the test strip, or information relating to the reference colour or to the reagent used in the current test strip. For example the final test result may be adjusted by taking into account a test strip specific deviation from a predetermined standard curve, which may be caused by a difference in a reagent or material used in the manufacture of the current test strip. Further, it is possible to associate a specific test strip to the determined result in a data base. It is also possible to use the computer-readable code to direct to a specific network resource for analysing the specific reaction used in the test strip, for example for opening a web page providing the results and possibly other information relating to the current measurement.

The presence of a bottom layer protects the reagent layer and any other layers present in the test strip. The bottom layer, especially together with other liquid impermeable layers, enable isolating the active parts of the test strip, such as a reagent layer or a pretreatment layer, and enable construction of a sample path through the test strip.

The feature that the reference colour area and the computer-readable code are at the same side of the bottom layer, preferably at the inner side of the bottom layer next to the reagent layer, provides an effect that the camera focusing to the area containing the colour reaction, the reference colour and the computer-readable code can be focused accurately to a level wherein the colour reaction occurs. For example the computer-readable code may be specifically used for defining the focusing point.

Further, as the colour reaction, the reference colour and the computer-readable code may all be on the reaction layer side of the bottom layer, the effect of the bottom layer affects to the detection of all of these in the same way. For example reflections or dimming caused by the bottom layer has the same effect for all the colour reaction, the reference colour and the computer-readable code. The effects of ambient light conditions to the measurement are minimized.

The feature that the non-transparent liquid impermeable layer, such as a white layer, on top of the reaction layer contains at least one liquid-permeable portion defining a measuring area, provides an effect that the liquid sample enters the measuring area from the surrounding area. Contaminating substances, for example coloured substances, possibly present in the liquid sample will retain in a layer above the non-transparent liquid impermeable layer and the liquid front entering the measuring area from the surrounding area, or from the edges of the measuring area, has a reduced amount of coloured or otherwise interfering substances left. The feature that there is no liquid-permeable portion at the centre of the measuring area provides an effect that the centre of the measuring area may be kept substantially free from any interfering coloured substances or impurities, which enhances the resolution of the colour reaction. The measuring area acting as a background is usually white, which facilitates the detection of the colour reaction. This feature is especially useful when a variety of different types of mobile terminals are used for detecting the reaction. As practically any kind of mobile terminal with a camera may be used for analysing the test strip, the enhanced detection of the colour reaction with minimized level of interfering impurities enables the use of wide variety of cameras with different qualities. In general, any mobile terminal with a camera capable of running the specific software may be used. The effects of the measuring conditions are minimized and therefore no extra devices or accessories, such as optical devices, for example light diffusers, to be connected to the mobile terminal, strip holders, reader devices or the like are required.

The above-mentioned features enable production of a disposable test strips, which may be sold as daily consumer goods. The strips are also recyclable or they may be discarded as mixed waste. As the analysis of the results may be carried out by using a regular mobile terminal, there is no need to invest to any specific reader devices. A test strip may be analysed practically anywhere by using the mobile terminal and the results may be obtained without a delay. The only cost for the consumer comes mainly from the strip, as the required software for the mobile device may be provided for free, or for a very low cost. Also a networked service may be used for analysing the results and for providing information. As the results obtained from the test are very accurate, the test strips of the embodiments are able to compete with the conventional test strips. As a matter of fact, the low costs and the easy availability of the tests enable providing completely new types of instant tests and services for the consumers.

Description of the drawings

Figure 1 shows an example of an arrangement of the layers of a multilayered test strip

Figure 2 shows an example of a removable cover layer

Figure 3 shows an example of a liquid impermeable top layer having an aperture for applying the sample

Figure 4 shows an example of an liquid impermeable layer comprising a sample pretreatment layer in an aperture

Figure 5 shows an example of a non-transparent liquid impermeable layer containing a liquid permeable portion comprising four holes

Figure 6 shows an example of an liquid impermeable layer comprising a reaction layer in an aperture

Figure 7 shows an example of the bottom layer seen from below the test strip

Detailed description

The present application provides a test strip for measuring an analyte from a liquid sample. In one embodiment the test strip is a disposable test strip. The test strip is optically readable with a mobile device.

In one embodiment the test strip comprises -a reaction layer, such as a fibrous reaction layer, containing reagent arranged to react with the analyte to produce a colour reaction indicating the presence or the concentration of the analyte, and -a liquid impermeable bottom layer containing at least one reference colour area and at least one computer-readable code associated with information related to the test strip. The reference colour area and the computer-readable code are visible at the bottom side of the test strip, and are preferably located close to each other, such as at the one end of the test strip.

The detection of the presence of the analyte refers to a situation wherein the presence of the analyte in the sample is not known, but the sample is suspected of including or containing a substance of interest, i.e. an analyte. A colour reaction indicates the presence of the analyte, and a lack of the colour reaction indicates the absence of the analyte. The colour reaction may also indicate the concentration of the analyte present in the sample.

In one embodiment the reference colour area and the computer-readable code associated with information related to the test strip are on the reaction layer side of the bottom layer, wherein the colour reaction, the reference colour area and the computer-readable code are visible through the bottom layer. There may be one or more reference colour areas on the test strip. There may be one or more computer-readable codes on the test strip.

The reaction layer refers to a layer containing a reagent. The reaction layer is usually liquid permeable. The reaction layer comprises a matrix, wherein the reagent may be present or bound. The matrix may be impregnated with the reagent. In one embodiment the reaction layer is a fibrous reaction layer. A fibrous reaction layer comprises a fibrous matrix, such as a matrix comprising fibrous organic material. A fibrous matrix may be woven or non-woven. In one embodiment the fibrous matrix is non-woven. Fibrous matrix will be wetted in the use and may become more transparent. The type of the reaction layer may be chosen according to the type of test to be carried out, for example depending on the reagent(s) used. The viscosity and other properties of the liquid sample may affect to the choice of layer material. For example a fibrous material may be used to provide a desired capillary action in the matrix and to affect to the speed and direction of the liquid flow. In one embodiment the fibrous reaction layer comprises fibrous organic material, such as cellulose, nitrocellulose, polyamide, polysulfone, polyester, polyacrylate, or polycarbonate. In one embodiment the fibrous reaction layer comprises fibrous natural organic material. Fibrous natural organic material may swell or change its permeability when wetted, which enables controlling the liquid flow, the volume of the liquid in the reaction chamber, or other properties of the matrix. In one embodiment the fibrous reaction layer does not contain inorganic fibrous material. In one embodiment the reaction layer consists of fibrous material, such as fibrous organic material. The reaction layer may be dry or wet. In one embodiment the reaction layer is dry. In one embodiment the reaction layer comprises paper or pulp, for example cellulose filter paper. In one embodiment the reaction layer comprises hydrophobic material. In one embodiment the reaction layer comprises hydrophilic material.

In one embodiment the reaction layer is white. White refers to white or substantially white colour, such as the colour of the matrix of the reaction layer, for example fibrous matrix. The reaction layer may be also coloured, for example in the case of pH indicator paper or the like. However, to enhance the detection of the colour reaction the reaction layer should itself have a light colour.

In one embodiment the reaction layer comprises cellulose or derivative thereof. “Cellulose” as used herein in general refers to cellulose and to derivatives thereof. In one embodiment the cellulose derivative is cellulose acetate. In one embodiment the cellulose derivative is cellulose triacetate. In one embodiment the cellulose derivative is nitrocellulose. In one embodiment the cellulose derivative is cellulose sulfate. In one embodiment the cellulose derivative is methyl cellulose. In one embodiment the cellulose derivative is ethyl cellulose. In one embodiment the cellulose derivative is hydroxyethyl cellulose. In one embodiment the cellulose derivative is hydroxypropyl cellulose. In one embodiment the cellulose derivative is hydroxyethyl methyl cellulose. In one embodiment the cellulose derivative is hydroxypropyl methyl cellulose. In one embodiment the cellulose derivative is ethyl hydroxyethyl cellulose. In one embodiment the cellulose derivative is carboxymethyl cellulose. A reference colour is a colour with a predetermined colour or intensity of the colour, which represents a known value of the colour reaction obtainable in the test. The reference colour area may contain one or more reference colours, for example at least two reference colours, or three, four, five, six, seven or more. In one embodiment the reference colour area comprises more than one reference colour. The more than one colours may also be present as separate reference colour areas. This may help adjusting the white balance. The amount of the reference colours may be associated with the computer-readable code. The reference colours may be arranged as an array or scale for constructing a standard curve which is used to determine a numerical value for the measured colour from the colour reaction. The construction and use of a standard curve is known for a person skilled in the art. In one example the reference colour area is rectangular. In one example the reference colour area is round or elliptical. In case of more than one reference colour the colours may be arranged as bands in the reference colour area. A standard curve is a type of graph used as a quantitative research technique. Multiple samples with known properties are measured and graphed, which then allows the same properties to be determined for unknown samples by interpolation on the graph. The samples with known properties are the standards, and the graph is the standard curve. The standard curve does not have to be presented as a graph for the user, but it may be implemented by a software in a computerized system having a memory and a processor, and used for calculating a numerical result for a colour reaction.

In one embodiment the reagent is arranged to react with the analyte to produce a colour reaction indicating the presence of the analyte. In one embodiment the reagent is arranged to react with the analyte to produce a colour reaction indicating the concentration of the analyte. Indicating the concentration of the analyte may also comprise indicating the presence of the analyte. In one embodiment the reagent is arranged to react with an intermediate agent to produce the colour reaction, wherein said intermediate agent indicates the presence or the concentration of the analyte. Such an intermediate agent may be formed in a pretreatment step, such as in a pretreatment layer. In one embodiment the colour reaction is arranged to provide an intensity of the colour which is proportional to the concentration of the analyte in the sample. In one embodiment the colour reaction is arranged to provide a specific colour, for example at a specific wavelength or wavelength range, which is proportional to the concentration of the analyte in the sample. Such different colours are used for example in pH tests, wherein a specific colour represents a specific pH value. In such cases more than one reagent may be used in the colour reaction. In general in the colour reaction a chromophore is formed.

The colour reaction refers to a reaction wherein a colour is produced, such as a colorimetric reaction. In general the colour reaction refers to a visible reaction, including also wavelengths visible only to the camera. Colorimetric analysis is a method of determining the concentration of a chemical element or chemical compound in a solution with the aid of a colour reagent. The amount or the presence of the analyte in the liquid sample is proportional to the intensity or the colour of the colour reaction. In one example high intensity of the colour indicates high concentration of the analyte in the sample, and vice versa. The colour of the colour reaction refers to the colour produced in the colour reaction, which may be characterized for example by its wavelength (or frequency). In one example the wavelength is within the visible spectrum, which is the range of wavelengths humans can perceive, approximately from 390 nm to 700 nm. Examples of approximate wavelength ranges for certain colours include 380-450 nm (violet), 450-495 nm (blue), 495-570 nm (green), 570-590 nm (yellow), 590-620 nm (orange), and 620-750 nm (red). The wavelength may also be outside the visible spectrum, either completely or partially, for example at the infra-red spectrum (about 700-1000 nm) or at the ultra violet spectrum (about 300-400 nm). In one example the useful wavelength range is 310-800 nm, or even 300-840 nm. Usually a colour reaction requires light to be detected. In general the ambient light is enough for the present embodiments and no extra light needs to be provided. The cameras in the mobile devices are usually arranged to adjust the light exposure to obtain a photograph of acceptable quality also at poor light conditions. As the reference colour area is close to the measuring area of the colour reaction, the light exposure will be adjusted to an optimal level for the measurement of the colour reaction. A camera may detect a broader wavelength range than a human eye, for example up to 840 nm, so an useful wavelength may also be outside the visible spectrum.

The colour reaction may also be a luminescence reaction. Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions, or stress on a crystal. One example of a luminescence reaction is chemilumenescence, which is a result of a chemical reaction. Another example of a luminescence reaction is biolumenescence, which is a result of a biochemical reaction. Still another example of a luminescence reaction is electrochemilumenescence, which is a result of an electrochemical reaction. Photoluminescence is a result of absorption of photons, such as fluorescence or phosphorescence.

The reagent refers to a substance which is used to detect or indicate the presence or the concentration of the analyte of interest. The reagent may contain one or more reagents required to produce the colorimetric reaction, or a reaction product, an observable colour. In one example the unreacted reagent is colourless or white, or it is not substantially visible from the matrix. The reagent may also be called for example as a reagent system, a colour reagent or an indicator reagent. The reagent may comprise for example a chemical reagent or a biochemical reagent, such as an enzyme. The reagent may react with the analyte directly or indirectly, for example via an intermediate agent or substance.

In one embodiment the reagent comprises an enzyme or an enzyme system bound or immobilized to the reagent layer, more particularly to the matrix of the reagent layer. The binding may be covalent or non-covalent. Examples of suitable enzymes include glucose oxidase, glucose dehydrogenase, and horseradish peroxidase. A liquid impermeable layer may be any layer comprising material which is not permeable to liquids, such as to water or other solvents. In one example a liquid impermeable layer comprises a layer of thermoplastic polymer. In one example a liquid impermeable layer comprises a layer of plastic. In one example a liquid impermeable layer comprises a layer of glass. A multilayered test strip may contain one or more stacked or piled liquid impermeable layers, for example at least two stacked layers. In one embodiment all the stacked liquid impermeable layers have the same width and length. Each layer, except the bottom layer, has a portion through which the sample travels, said portion containing one or more apertures, holes or perforations, as described herein. The use of stacked liquid impermeable layers, such as plastic films, adds rigidity to the test strip and enables the application of specific functional layers, such as a reaction layer or a pretreatment layer, to a desired location in the test strip. Preferably at least one liquid impermeable layer comprises rigid material. A liquid impermeable layer may be transparent or non-transparent, but the bottom layer should be at least partially transparent to enable the visualization of at least the colour reaction. In one embodiment a non-transparent liquid impermeable layer is white.

In one embodiment the test strip further comprises a non-transparent liquid impermeable layer, such as a white layer, on top of the reaction layer, wherein said non-transparent liquid impermeable layer contains at least one liquid-permeable portion defining a measuring area, wherein the at least one liquid-permeable portion is at the outer edge of the measuring area and there is no liquid-permeable portion at the centre of the measuring area. On top of the reaction layer” means that the measuring area is aligned with an area wherein the colour reaction takes place, such as a reaction area.

In one embodiment a test strip comprises -a non-transparent liquid impermeable layer containing at least one liquid-permeable portion defining a measuring area, wherein the at least one liquid-permeable portion is at the outer edge of the measuring area and there is no liquid-permeable portion at the centre of the measuring area, on top of a -a reaction layer, such as a fibrous reaction layer, containing reagent arranged to react with the analyte to produce a colour reaction indicating the presence or the concentration of the analyte, on top of a -a liquid impermeable bottom layer containing a reference colour area. In a further embodiment said test strip comprises a computer-readable code associated with information related the test strip, preferably on the reaction layer side, as described in the other embodiments. In another further embodiment said test strip comprises a sample pretreatment layer on top of the non-transparent liquid impermeable layer.

In one embodiment the bottom layer is a transparent liquid impermeable layer. The thickness of the liquid impermeable bottom layer may be in the range of 50-200 pm, such as 50-150 pm, for example about 100 pm. The bottom layer may be made of transparent polymeric film. In one embodiment the bottom layer is made of transparent PET film. The bottom layer may be completely or partially transparent. At least the parts containing the reference colour area, the computer-readable code and the area wherein the reaction colour will be formed, i.e. the location corresponding to the measuring area, shall be transparent to enable these locations being visible through the bottom layer. In one embodiment the location corresponding to the measuring area is surrounded by a non-transparent area, for example leaving a round transparent spot, which enables the detection of the colour reaction accurately at the middle of the reaction/measuring area. This may decrease any interference from other coloured substances or improper reaction at the outer edges of the measuring area.

In one embodiment the liquid-permeable portion of the non-transparent liquid impermeable layer comprises one or more holes, such as holes having a diameter in the range of 0.1-1 mm. There may be more than one hole, for example two, three, four, five, six, seven, eight, nine, ten or even more. In one example there are four holes. The hole may be called also an aperture, and it may be round, elliptical, angular or elongated, such as a slit or a slot.

The thickness of the non-transparent liquid impermeable layer may be in the range of 50-150 pm, for example in the range of 80-120 pm. The nontransparent liquid impermeable layer may be made of polymeric film, such as thermoplastic polymer. In one embodiment the non-transparent liquid impermeable layer comprises PET film, such as oriented PET film (OPET). In one embodiment the non-transparent liquid impermeable layer comprises poly-ethylene-naphthalate (PEN) film. In one embodiment the non-transparent liquid impermeable layer comprises polycarbonate (PC) film. In one embodiment the non-transparent liquid impermeable layer comprises polymethyl methacrylate (PMMA) film.

In one embodiment the liquid-permeable portion of the non-transparent liquid impermeable layer comprises a plurality of perforations, for example arranged as a circle. The diameter of such perforations may be smaller than separate holes, for example in the range of 0.01-0.2 mm. In one embodiment the liquid-permeable portion of the non-transparent liquid impermeable layer comprises one or more elongated apertures or holes, for example one or more arched aperture(s) arranged as a circle.

The holes or the perforations may be made mechanically, or they may be made with a non-contacting method, such as by using laser. The surface of the non-transparent liquid impermeable layer may be coated to adjust and control the liquid flow, for example with a hydrophilic coating, or with a hydrophobic or superhydrophobic coating, such as silicone-based coating. In one example the surface of the non-transparent liquid impermeable layer is hydrophilic. In one example the surface of the non-transparent liquid impermeable layer is hydrophobic. The holes or the perforations have an effect to the flow speed and to the direction of the liquid flow. The specific treatment of the non-transparent liquid impermeable layer may provide a controlled capillary action on the surface affecting to the flow of the sample.

The liquid-permeable portion may form a ring or other form, for example angular form, which may be approximately the same size as the reaction area below, or it may be larger, for example having a diameter of about 110% of the diameter of the reaction area, or about 120%, about 130%, about 140% or about 150%. The liquid-permeable portion defines a measuring area, which forms a background for the colour reaction at the reaction layer below. The liquid-permeable portion is arranged in such way that the liquid entering to the reaction layer or area through the holes or perforations will travel from the outer edge of the measuring area to the middle of the measuring area. This way a liquid sample containing minimum amount of interfering substances, such as coloured substances present in the original sample, will be present finally at the middle of the measuring area. The reaction may be visible from the bottom of the test strip only at the middle of the measuring area to minimize the effect of the interfering substances to the test results.

In one embodiment the non-transparent liquid impermeable layer is a white layer, or it may have a very light colour. Such a background is suitable for most colour reactions. However, it is possible to use other types of background. If the colour reaction is for example a luminescence reaction, a black background could be used. In one example the test strip has a white background colour (for example RGB=255,255,255), which may act as one reference colour to be used for calibration. In one example the white colour is located at the non-transparent liquid impermeable layer, which acts as the background for the colour reaction.

In one embodiment the test strip further comprises a sample pretreatment layer on top of the non-transparent liquid impermeable layer. In one embodiment the sample pretreatment layer is a fibrous layer. A pretreatment layer is used to perform a pretreatment for the sample, usually to prepare the sample for the measurement. In one example the pretreatment layer retains material from the liquid sample, for example coarse material or coloured material, which would interfere the colour reaction or the measurement. In such case most of the coloured material remains behind the non-transparent liquid impermeable layer and is not visible at the measuring area. In one example the pretreatment layer contains one or more chemicals or reagents for pretreating the liquid sample, in general pretreatment agents. Such pretreatment agents may be used to bind certain components of the liquid sample to retain them in the pretreatment layer. The pretreatment agents may be used to treat the sample by digesting it, for example to release the analyte of interest. Such a technique may be used for example for pretreating cells, such as red blood cells, or structures such as vesicles, liposomes or micelles, by using enzymes or other agents to digest or disintegrate thereof. Examples of such pretreating agents include enzymes, chaotropic agents, binders, antibodies, lectins, salts, or the like. In one example a pretreating agent is used to provide a precursor from the analyte for the colour reaction, e.g. an intermediate molecule, agent or substance which will enter the reaction layer to the colour reaction. The amount of the precursor correlates with the amount of the analyte, for example the precursor is formed in equal molar amounts.

The pretreatment layer comprises a matrix. In one embodiment the pretreatment layer is a fibrous pretreatment layer. A fibrous pretreatment layer comprises a fibrous matrix, such as a matrix comprising fibrous organic material. The matrix may be impregnated with the pretreatment agent. A fibrous matrix may be woven or non-woven. In one embodiment the fibrous matrix is non-woven. The type of the pretreatment layer may be chosen according to the type of test to be carried out. The viscosity and other properties of the liquid sample may affect to the choice of layer material. For example a fibrous material may be used to provide a desired capillary action in the matrix and to affect to the speed and direction of the liquid flow. In one embodiment the fibrous pretreatment layer comprises fibrous organic material, such as cellulose, nitrocellulose, polyamide, polysulfone, polyester, polyacrylate, or polycarbonate. In one embodiment the fibrous pretreatment layer does not contain inorganic fibrous material. In one embodiment the pretreatment layer consists of fibrous material, such as fibrous organic material. Fibrous natural organic material may swell or change its permeability when wetted, which enables controlling the liquid flow, the volume of the liquid in the pretreatment chamber, or other properties of the matrix. In one embodiment the fibrous organic material is swellable material. The pretreatment layer may be dry or wet. In one embodiment the pretreatment layer is dry. In one embodiment the pretreatment layer comprises paper or pulp, for example cellulose filter paper. In one embodiment the pretreatment layer comprises hydrophobic material. In one embodiment the pretreatment layer comprises hydrophilic material. In one example the hydrophilic material comprises long inorganic fibers.

In one embodiment the pretreatment layer comprises cellulose or derivative thereof. “Cellulose” as used herein in general refers to cellulose and to derivatives thereof. In one embodiment the cellulose derivative is cellulose acetate. In one embodiment the cellulose derivative is cellulose triacetate. In one embodiment the cellulose derivative is nitrocellulose. In one embodiment the cellulose derivative is cellulose sulfate. In one embodiment the cellulose derivative is methyl cellulose. In one embodiment the cellulose derivative is ethyl cellulose. In one embodiment the cellulose derivative is hydroxyethyl cellulose. In one embodiment the cellulose derivative is hydroxypropyl cellulose. In one embodiment the cellulose derivative is hydroxyethyl methyl cellulose. In one embodiment the cellulose derivative is hydroxypropyl methyl cellulose. In one embodiment the cellulose derivative is ethyl hydroxyethyl cellulose. In one embodiment the cellulose derivative is carboxymethyl cellulose.

In one embodiment the reaction layer and/or the pretreatment layer are arranged into an aperture in a liquid impermeable layer and aligned with the measuring area in the non-transparent liquid impermeable layer to form a sample path through the test strip. A reaction layer in an aperture may be called a reaction area or a reaction chamber. A pretreatment layer in an aperture may be called a pretreatment area or a pretreatment chamber. The thickness of the reaction layer and/or the fibrous pretreatment layer is usually the same as the thickness of the corresponding liquid impermeable layer. The diameter and the form of the aperture is approximately the same as the diameter and the form of the layer applied into the aperture. The sample path is a path going through at least two layers of a multi-layered test strip. The sample path is perpendicular to the plane of the test strip. The use of a sample path in a multi-layered test strip enables controlling the flow of the liquid, the volumes of the chambers arranged in the sample path and other features relating to the measuring conditions. When a sample has entered a chamber, the flow back is minimal. The user does not have to dose a specific amount of the liquid sample onto the test strip but the test strip may be dipped directly into the liquid. The other parts of the test strip comprises rigid material, such as polymer layers, which provide good mechanical properties for the strip. The liquid impermeable materials provide a waterproof or water-resistant structure.

The thickness of a liquid impermeable layer 12 having an aperture containing a piece of sample pretreatment material in a sample pretreatment area 18 may be in the range of 100-250 pm, such as 150-200 pm, for example about 180 pm. In one example the liquid impermeable layer 12 is made of acrylic film.

The thickness of a liquid impermeable layer 14 having an aperture containing a piece of reaction matrix material containing reagent in a reaction area 20 may be in the range of 100-250 pm, such as 150-200 pm, for example about 180 pm. In one example the liquid impermeable layer 14 is made of acrylic film.

The thickness of a liquid impermeable layer and the size of the aperture therein may be adjusted to obtain a desired volume for a reaction chamber comprising the reaction layer or for a pretreatment chamber comprising the pretreatment layer. The volume may be adjusted to obtain a desired colour reaction with the used sample type. Also properties such as the concentration of a reagent in a chamber and the flow properties of a matrix material may be adjusted to obtain a desired test reaction, which provides reliable and linear colour reaction and results with the used sample. A chamber may be designed to hold a predetermined amount of the sample liquid only to provide reliable test results.

In one embodiment the test strip comprises a liquid impermeable top layer 11 having an aperture 17 for applying the sample. This may be also called as a sample well. The aperture 17 is on top of the sample path through the test strip and it may have the same diameter or size as the other apertures below, or it may be smaller, for example about 90% of the aperture having the pretreatment layer, or about 80%, or about 70%. The aperture 17 may be also greater than the apertures below. The thickness of the top layer may be in the range of 50-400 pm, for example in the range of 50-70 pm. In one example the liquid impermeable top layer 11 is made of acrylic film.

In one embodiment a liquid impermeable layer 11, 12, 13, 14, 15 comprises a polymeric layer or film, such as a plastic film, for example thermoplastic or thermosetting polymer film. Examples of thermoplastic polymers include acrylic, acrylonitrile butadiene styrene (ABS), Nylon, polylactic acid (PLA), polybenzimidazole, polycarbonate, polyester, polyethylene, polyethylene terephthalate (PET), polypropylene, polystyrene, polyvinylchloride (PVC) and Teflon. One or more of the liquid impermeable layers may comprise said polymeric layer or film, which may be the same or different in the different liquid impermeable layers.

The layers may be attached to each other with a suitable adhesive. The adhesive may be applied between the layers during the manufacture of the test strip, for example an emulsion adhesive or a hot-melt adhesive, or the adhesive may be contained in a film layer, such as a pressure-sensitive adhesive. Examples of pressure-sensitive adhesive include acrylic based adhesives and natural or synthetic rubber containing elastomers, tackifiers and/or silicone based pressure sensitive adhesives. Pressure sensitive adhesive, also known as self-stick adhesive, forms a bond when pressure is applied at room temperature. In one embodiment the test strip does not contain other layers but the mentioned ones attached to each other with the adhesive. Especially the non-transparent liquid impermeable layer is directly attached via adhesive to the liquid impermeable layer containing the reaction layer and/or to the liquid impermeable layer containing the pretreatment layer. In one embodiment each layer disclosed in the embodiments is directly attached to the next layer via adhesive.

In one embodiment a liquid impermeable layer comprises acrylate polymers, such as an acrylate film. Acrylate polymers belong to a group of polymers which could be referred to generally as plastics. They are noted for their transparency, resistance to breakage, and elasticity. They are also commonly known as acrylics or polyacrylates.

Polyethylene is a thermoplastic polymer which may be classified into several different categories based on density and branching. Examples of such categories include ultra-high-molecular-weight polyethylene (UHMWPE), ultra-low-molecular-weight polyethylene (ULMWPE or PE-WAX), high-molecular-weight polyethylene (HMWPE), high-density polyethylene (HDPE), high-density cross-linked polyethylene (HDXLPE), cross-linked polyethylene (PEX or XLPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), very-low-density polyethylene (VLDPE) and chlorinated polyethylene (CPE). The melting point and glass transition temperature may vary depending on the type of polyethylene. For medium- and high-density polyethylene the melting point is typically in the range of 120-180°C, and for average low-density polyethylene in the range of 105-115°C.

Polypropylene is a thermoplastic polymer having a glass transition temperature of about -20°C (atactic polypropylene) or about 0°C (isotactic polypropylene). Examples of polypropylenes or polymers derived from polypropylene include PP-homopolymers, random PP copolymers , PP block copolymers, PP terpolymers, PP elastomers and PP plastomers

Depending on the chemical structure, polyester may be thermoplastic or thermoset. Examples of polyesters include for example homopolymers, such as polyglycolic acid, polylactic acid (PLA), polycaprolactone (PCL), poly-hydroxyalkanoate (PHA) and polyhydroxybutyrate (PHB); aliphatic copolymers, such as polyethylene adipate (PEA) and polybutylene succinate (PBS); semi-aromatic copolymers, such as polyethylene terephthalate (PET), polyethylene terephthalate glycol modified (PETG), polybutylene terephthalate and polytrimethylene terephthalate (PTT); or aromatic copolymers such as Vectran.

Polyethylene terephthalate (PET) is the most common thermoplastic polymer resin of the polyester family. Polyethylene terephthalate glycol modified (PETG) refers to PET wherein cyclohexane dimethanol has been added to the polymer backbone in place of ethylene glycol. PETG is clear amorphous thermoplastic which can be used in several molding applications. PET can also be modified with isophthalic acid which replaces some of the 1,4-(para-) linked terephthalate units. This creates an angle in the PET chain, interfering with crystallization and lowering the polymer's melting point. PET has a glass transition temperature of about 70°C.

Polylactide or polylactic acid (PLA) has benefits due to its eco-friendly nature like development from renewable materials and biodegradability. Polylactide is a biodegradable, thermoplastic, aliphatic polyester derived from lactic acid obtained from renewable or non-renewable resources, e.g. corn-starch based lactic acid. Polylactide has initially partially crystalline structure containing both crystalline and amorphous regions. Polylactide may also be totally amorphous. It can be processed in similar manner than many thermoplastics into fibres, films or other products manufactured by conventional melt processsing techniques. Due to the chiral nature of lactic acid and different cyclic diesters, lactide stereoisomers, several distinct forms of polylactide exists such as homopolymer of L- lactide PLLA and stereocopolymers of L-lactide and D-lactide P(L/D)LA or L-lactide and DL-lactide P(L/DL)LA. Polylactide has a glass transition temperature of about 60-65°C.

Polystyrene (PS) is a synthetic aromatic polymer made from the monomer styrene. Polystyrene is a thermoplastic polymer having a glass transition temperature of about 100°C. Examples of polymer derived from polystyrene include styrene block-copolymers, such as SBS, SIS, SEBS, SEPS, SIBS, SEP, SEEPS and the like.

As shown in Figure 1, in one embodiment the test strip 10 comprises the following layers in the following order: -a (first) liquid impermeable top layer 11 comprising an aperture 17 for applying the sample, -a (second) liquid impermeable layer 12 comprising a sample pretreatment layer 18 in an aperture, -a non-transparent (third) liquid impermeable layer 13 containing at least one liquid-permeable portion 26 defining a measuring area 19, -a (fourth) liquid impermeable layer 14 comprising a reaction layer 20 in an aperture, and -a (fifth) liquid impermeable bottom layer 15 containing a reference colour area 21 and a computer-readable code 22 associated with information related to the test strip on the reaction layer side. The aperture 17, the sample pretreatment layer 18 in an aperture, the measuring area 19 and the reaction layer 20 in an aperture are all aligned to form a sample path 23 through the test strip. There may also be a removable cover layer 16 which protects the sample aperture 17.

The computer-readable code is associated with information related to the test strip. The information related to the test strip may refer to information identifying the test on the test strip, information identifying the test strip lot, or even the individual test strip. The information may contain the manufacturing date or location of the test strip, or it may contain other information. The information may contain information which may be used for calculating the measurement result, such as a correction or calibration factor, the information may be off-line or on-line information. In one example the information comprises an off-line table. The code being associated with the information means that the code contains such information and/or the code contains a pointer to an external resource containing said information, such as a networked resource, for example a cloud service. In one example the information comprises an on-line network address. The pointer may be a hyperlink. One example of such resource is a URL, or more particularly a www address. The resource may also be a file stored on the mobile device.

The “computer-readable code” as used herein refers to one or more computer-readable codes. In one embodiment the test strip contains two computer-readable codes. The two codes may contain different information. The two codes may be same type of codes or they may be different types of codes. In one embodiment one code contains a pointer or a hyperlink to an external resource, such as a URL, and the other code contains information relating to the current test strip, such as the current measurement or test, or to one or more reference colour(s). The two codes may also contain reference colours, such as a different reference colour in each code. In one embodiment the reference colour area contains one of the codes. In one embodiment the measurement area is between the two computer-readable codes.

The computer-readable code is as an optical or visual computer-readable code, such as a barcode. A barcode may be one-dimensional (1D) or two-dimensional (2D), such as a QR code. Although 2D systems use a variety of symbols, they are generally referred to as barcodes as well. The computer-readable code may be also called as a machine-readable code. Herein a computer-readable code means that the code may be read with a mobile terminal.

In one embodiment the computer-readable code comprises a two-dimensional bar code. In one embodiment the computer-readable code is a QR code. QR code is a trademark for a type of matrix barcode (or two-dimensional barcode) first designed for the automotive industry in Japan. A barcode is a machine-readable optical label that contains information about the item to which it is attached. A QR code uses four standardized encoding modes (numeric, alphanumeric, byte/binary, and kanji) to efficiently store data; extensions may also be used. In an example a QR code consists of black modules (square dots) arranged in a square grid on a white background, which can be read by an imaging device (such as a camera) and processed using Reed-Solomon error correction until the image can be appropriately interpreted. The required data are then extracted from patterns present in both horizontal and vertical components of the image. QR codes may store for example addresses and URLs. An image of the QR code may be scanned for example with a camera phone equipped with a suitable reader application to display information, or to connect to a wireless network, or open a web page. This act of linking from physical world objects is termed hardlinking or object hyperlinking. QR codes can be used to log in into websites.

In one embodiment the computer-readable code comprises one or more characters, such as letters or numbers, for example a text or a number sequence or a combination thereof. Such a code may be read and recognized by using optical character recognition (OCR).

When a computer-readable code is used in the test strip, the user does not have to type any information or otherwise specify the test, but all the information required to carry out the measurement and analysis may be included in the code, and read by the mobile terminal.

In one embodiment the computer-readable code contains a hyperlink or a URL directing to a networked service providing test strip specific information, such as a lot identifier, test identifier and/or reference colour information. The reference colour information may be for example the amount of the reference colours on the test strip, the known numerical values representing each colour or each intensity of a colour in a reference colour area, a correction or a calibration factor which may be used to correct the measured and calculated numerical values of a specific test strip batch or lot with a known error. The test identifier may indicate the type of the test, whereupon the system or software may recognize the corresponding reference colour(s) and calculate the numerical result of the test. When a lot or batch of a test strip is identified, any factors affecting to the results specific for the batch or lot in question may be taken into account when calculating the result of a test.

The networked service may be a cloud service, and at least a part of the analysis may be carried out by using cloud computing. Cloud computing involves deploying groups of remote servers and software networks that allow centralized data storage and online access to computer services or resources.

In one embodiment the computer-readable code contains a reference colour. In one embodiment the reference colour area and the computer-readable code are the same, i.e. the computer-readable code contains the reference colour. In one embodiment the reference colour are and the computer-readable code are separate. In such case the computer-readable code may provide a different reference colour than in the reference colour area. In one example the computer-readable code is black, so it provides a reference for black colour. In one example the computer-readable code is dark blue. A black or otherwise dark colour will help focusing the camera to the right level at the multi-layered test strip. The location of the computer-readable code, and/or the location of the reference colour area, may be used as a marker for aligning the image, for example to define the location of the measurement area. In some cases the colour reaction at the measurement area may not be visible, or it is poorly visible, or there is no colour reaction, so an alignment with the other references may be required to find the proper spot to analyse. In one example the measurement area is between the computer-readable code and the reference colour area, preferably at a predetermined location having a known distance from an aligning marker. In one example the center of the measurement area has a distance d1 from the closest edge of the reference colour area and distance d2 from the closest edge of the computer-readable code. The distances d1 and d2 may be for example in the range of 2-20 mm, such as in the range of 5-10 mm.

The test strips may be used for carrying out a variety of tests, and for measuring and analysing several types of analytes from samples. The sample may be any liquid sample, which may contain the analyte of interest. In one embodiment the sample is an aqueous sample. In one embodiment the sample contains organic solvent.

An aqueous sample may be obtained from any water-containing source, or water may be added to a concentrated sample to enable the measurement. In one embodiment the aqueous sample is obtained from a water source, such as groundwater, waste water, industrial water, water from a water system, such as a lake, river, sea or pond, pool water, and the like.

In one embodiment the sample is a water sample. The test may be carried out for measuring the quality of the water. The analyte of interest may be for example hydronium ion (pH measurement), chloride, ammonia, nitrate, nitrite, orthophosphate, phosphorus, bicarbonate alkalinity, carbonate alkalinity, alkalinity, potassium, sodium, sulfate, aluminium, boron, calcium, iron, magnesium, zinc, S1O2, fluoride, cyanide, hydrogen sulphide, chlorophyll a, pheophytin a, mercury, lead, and BTEX (benzene, toluene, ethylbenzene and xylenes). The test may measure in general pH, ion concentration or water hardness.

In one embodiment the sample is obtained from soil, for example for determining pH or nutrient content of the soil. Such applications are useful for example in agriculture and gardening. In such cases the soil is in general wet or may be wetted. The soil may be wetted with water in a predetermined ratio. In one example one part of soil is mixed with two parts of water. The water does not have to be distilled water or any other highly purified water, but in general any water available may be used if a calibration is first made using the water only as a sample. The measuring software is calibrated with this water measurement and after that the actual soil measurements may be carried out using the same water as a diluent.

In one embodiment the test is pH test. In such case the analyte of interest is actually hydronium ion. In general, pH is the negative log of the activity of the hydrogen ion in an aqueous solution. pH measurements are important for example in medicine, biology, chemistry, agriculture, forestry, food science, environmental science, oceanography, civil engineering, chemical engineering, nutrition, water treatment and water purification.

Mathematically, pH is the negative logarithm of the activity of the (solvated) hydronium ion, more often expressed as the measure of the hydronium ion concentration. Chemical indicators may be used to measure pH, by making use of the fact that their colour changes with pH. The obtained colour is compared to one or more standard colours in the reference area to determine the pH value. Examples of useful indicators include thymol blue, methyl red, bromothymol blue and phenolphthalein. pOH is sometimes used as a measure of the concentration of hydroxide ions, OH', or alkalinity. pOH values may be derived from pH measurements.

In one embodiment the sample is a biological sample, for example a sample obtained from an human individual, for example from a bodily fluid. In one embodiment the sample is obtained from bodily fluids, such as urine, blood, sweat, saliva and the like.

The analyte of interest may be for example a drug, a protein, a fatty acid, a metabolite, a vitamin, an antigen, a hormone, an electrolyte, or any other substance of a living organism. Examples of analytes measurable from blood include sodium, potassium, calcium, chloride, copper, iron, phosphate, ammonia, lithium, magnesium, bicarbonate urea, creatinine, serum calcium, human serum albumin, bilirubin, alkaline phosphatase, aspartate amino transferase, alanine amino transferase, cholesterol, such as total cholesterol, HDL, LDL or triglycerides, glucose, haemoglobin, troponin, myoglobin, CK-MB, fibrinogen, vitamin D, folic acid, vitamin B12, vitamin A, DHEA, TSH, testosterone, estradiol, HIV, and glucose. Examples of analytes measurable from saliva include androgens, antigens, estrogen, prostate-specific antigen, lipid peroxides, tumor suppressor protein p53, transferrin, vitamin C, igG antibodies, amphetamine, metamphetamine, ethanol, opiates, methadone, morphine, benzodiazepines, lutenizing hormone, chromogranin A, pH, peroxidase, hydroxyproline, calcium, estrogens, and cortisol. Examples of analytes measurable from urine include testosterone, β-2-microglobulin, anti-HCV, vitamin C, esctasy, heroin, cocaine, 6-monoacetylmorphine, opiates, methadone, morphine, benzodiazepines, hCG, luteinizing hormone, glucose, bilirubin, ketone, pH, protein, urobilinogen, nitrite, leukocytes and cortisol. Examples of analytes measurable from sweat include chloride, pH, melatonin, lactate, chloride and urea.

The test strip may be analysed by using a mobile terminal having a camera. Alternatively any other image capture module may also be used, such as a scanner. A mobile terminal as used herein refers to a terminal including a processor, memory, user interface and a camera, all operatively connected. The mobile terminal may also be configured to receive a memory device, such as a memory card, for transferring data and/or software. The mobile terminal has a display, such as a touch sensitive display. In practice the mobile terminal is a mobile computer, which is capable of running computer programs. In one embodiment the mobile terminal is configured to communicate with an external device using wireless network. Such a mobile terminal contains a transmitter and a receiver. A wireless network is any type of computer network that uses wireless data connections for connecting network nodes. Examples of wireless networks include cell phone networks, WiFi and Bluetooth. Software may be downloaded to the mobile device by using the wireless network.

In one embodiment the mobile terminal is a mobile phone, such as any suitable smartphone having a camera. In one embodiment the mobile terminal is a tablet. Also other types of mobile terminals having a camera may be used, such as phablets, cameras, laptops, and the like, said mobile terminal preferably having a network connection. The mobile terminal is capable of running a specific software arranged to carry out one or more of the necessary steps, for example to analyse the photograph and/or to obtain a test result. In one example the software is HTML5-based. The mobile terminal may have a variety of operating systems, such as Android, iOS, Windows Phone, BlackBerry, Firefox OS, Sailfish OS, Tizen, or Ubuntu touch OS, or any other mobile operating system. A specific software is required for analysing the results from the test strip. The software comprises a computer-executable program code arranged to be run on the mobile terminal, which may also be considered as a software product. One embodiment provides a computer-readable data storage medium having the computer-executable program code, which is stored operative to perform the steps or the functions described herein. The data storage medium may be a physical memory device, such as a memory card or stick, or the data storage medium may be contained in a networked service, such as a service providing an application store for the mobile device. One embodiment provides a networked service containing a memory storage, such as a hard drive or an array of hard drives, said memory storage containing the computer-executable program code. In the use the computer-executable program code is stored operatively in the mobile terminal, which means that the code may be run on the operating system of the terminal. Such a software may be provided, or instruction for obtaining the software may be provided together with the test strip. For example the package of the test strip may contain a www address or a QR code directing to such an address wherefrom the software may be downloaded. In general the software may be downloadable from an application store or from a website. Once installed the software may be run on the mobile device. The software may use the camera routines of the mobile terminal for obtaining an photograph of the test strip. The software may expand the functionality of the existing camera application or it may be run separately. The software may be used to obtain the photograph with the camera, or the software may use an existing photograph already taken with the camera. A single photograph or a series of photographs may be used, for example a video.

The photograph may be a full size photograph, in general a colour photograph, obtained with the camera of the mobile device. The photograph may also be called as an image or a photo. One or more photographs may be taken. In case of plurality of photographs a video may be obtained, which may comprise a series of still images with associated time information. The photograph may be taken without a flash or with a flash. In one example the photograph is taken without flash. In one example also a macro focusing function of the camera is used. The functionality of the camera is controlled with the software. In one example the photograph is processed to obtain a more compact image. The photograph may be resized, i.e. the resolution of the photograph may be lowered, to save resources, such as memory, processing resources and/or data transfer bandwidth. The amount of colours in the photograph may be reduced for the same reasons, or the colours may be converted to a grayscale. The photograph may be packed by using any suitable image packing algorithm. In one example the used software recognized the area on the bottom of the test strip containing the reference colour area and the colour reaction area. This area may be cropped from the photograph to discard any other parts and to have an image containing only the information relating to the colour reaction and the reference colour. The image may be zoomed, tilted, panned, straightened, or enhanced. Image recognition methods may be used to recognize the computer-readable code, the exact location of the reference colour area or possible text portions, for example by using optical character recognition (OCR). These steps may be carried out at the mobile terminal or at a remote service. However, as the acquiring of the image is usually visualized to the user in real time, these steps are in such case carried out at the mobile terminal. The computer-readable code may be included or it may be also discarded from the image after it has been read. The pixels of the image are saved as colour values, such as RGB values (for example 16 million colours). The obtained image may be further processed. For example the mean average values of the colour components (RGB, CMYK, etc.) may be obtained from the image and used for approximating each component of the measuring result. The measurement may be based on a single colour component, or to more than one colour components. If a single colour component is used the resolution may have 255 steps. The image may be sent to an external service, such as to a networked service, to be analysed.

To obtain a reliable measuring result, the image must be calibrated to eliminate the effects of the external conditions and the user. For example the white balance is adjusted for the reference colour(s), and the lightning is normalized. In one example a white background colour of a test strip and a black colour of a computer-readable code may be used as references for adjusting the white balance of the image. All the processed images should be at the same level regardless of the camera, photographing environment or photographing conditions. In one example the calibration begins with calculation of the colour balance and for the actual calibration a test strip type specific algorithm is used. In one example the computer-readable code defines the reference information used for the calibration. The algorithm may also recognize non-linear colour correlation. In one example the result obtained with the calibration algorithm is adjusted with the reference colour. The calibration algorithm calculates a calibrated colour value from to the colour reaction and the corresponding (numerical) measurement result. The software may store the original image and any meta data associated with it.

In one example more than one photographs are obtained. This may be done to obtain a series of images to monitor the development of the colour reaction as a function of time. Information relating to the speed of the colour reaction may be used to calculate the measurement result.

One embodiment provides a software product, such as a computer-executable program code, for determining the presence or the concentration of an analyte on a test strip, said software product comprising a computer-executable program code which, when run in a mobile terminal having a camera, is arranged to, or is operative to, -obtain a photograph of a bottom side of the test strip described herein, -determine the intensity or the colour of the colour reaction indicating the presence or concentration of the analyte and the intensity or the colour of at least one reference colour in the reference colour area from the photograph, -identify the test strip with the information associated with the computer-readable code, and to -determine the presence or the concentration of the analyte by using the determined intensity or the colour of the colour reaction and using the intensity or the colour of at least one reference colour in the reference colour area as a standard. The software may be arrange to output a result indicating the presence or the concentration of the analyte, for example one or more numerical values, such as a concentration of the analyte, or a verbal or graphical output describing the result, such as a text or an image, or a combination thereof.

One embodiment provides a mobile terminal having said software installed.

One embodiment provides a method for determining the presence or the concentration of an analyte on a test strip, the method comprising -obtaining a photograph of the test strip described herein, such as a photograph of a bottom side of the test strip, -determining the intensity or the colour of the colour reaction indicating the presence or concentration of the analyte and the intensity or the colour of at least one reference colour in the reference colour area from the photograph, -identifying the test strip with the information associated with the computer-readable code, and -determining the presence or the concentration of the analyte by using the determined intensity or the colour of the colour reaction and using the intensity or the colour of at least one reference colour in the reference colour area as a standard. Said method may be arranged to be carried out by the computer-executable program code.

In one embodiment obtaining a photograph of the test strip, for example a photograph of a bottom side of the test strip, means that when the camera shoots or sees the bottom side of the test strip, for example as a preview, the software is arranged to recognize the elements on the test strip and determine the areas required for the further analysis of the test reaction. In one embodiment obtaining a photograph of the test strip means that an existing photograph of the test strip is used for the analysis. For example a photograph stored in a memory of the mobile device is read and analysed. In one embodiment the software is arranged to recognize the computer-readable code and optionally also the reference colour area, and by using the location of the code, and optionally the reference colour area, to define the location of the colour reaction. In practice the software may show in a display the preview of the camera and when the elements of the test strip are recognized, they are framed in the display to indicate that they are recognized. The software may then obtain the photograph automatically, or the user may trigger a key, such as a physical key or a virtual key on a touch sensitive screen, to take the photograph.

In one embodiment at least one of the following is arranged to be carried out in the mobile terminal: -determining the intensity or the colour of a colour reaction, -determining the intensity or the colour of at least one reference colour in the reference colour area, -identifying the test strip by using the computer-readable code, and -determining the presence or the concentration of the analyte by using the intensity or the colour of at least one reference colour in the reference colour area as a standard .

In one embodiment at least one of the following is arranged to be carried out in a remote service: -determining the intensity or the colour of a colour reaction, -determining the intensity or the colour of at least one reference colour in the reference colour area, -identifying the test strip by using the computer-readable code, and -determining the presence or the concentration of the analyte by using the intensity or the colour of at least one reference colour in the reference colour area as a standard .

In one embodiment the information associated with the computer-readable code is used for determining the presence or the concentration of the analyte.

One embodiment provides a method for measuring an analyte from a liquid sample, the method comprising -providing the test strip described herein, -providing a mobile terminal having a camera and the software described herein, -applying the liquid sample onto the test strip to obtain a colour reaction indicating the presence or concentration of the analyte, -obtaining a photograph of the colour reaction, the reference colour area and the computer-readable code from the test strip, such as the bottom side of the test strip, by using the mobile terminal having a camera, and -by using the software -determining the intensity or the colour of the colour reaction and the intensity or the colour of at least one reference colour in the reference colour area from the photograph, -identifying the test strip with the information associated with the computer-readable code, and -determining the presence or the concentration of the analyte by using the determined intensity of the colour reaction and the intensity or the colour of at least one reference colour in the reference colour area as a standard. The software as used herein refers to the computer-executable program code, which is stored operatively (or “installed”) in the mobile terminal.

In one embodiment at least one of the following is carried out in the mobile terminal: -determining the intensity or the colour of a colour reaction, -determining the intensity or the colour of at least one reference colour in the reference colour area, -identifying the test strip by using the computer-readable code, and -determining the presence or the concentration of the analyte by using the intensity or the colour of at least one reference colour in the reference colour area as a standard.

In one embodiment the intensity or the colour of a colour reaction and the intensity or the colour of at least one reference colour in the reference colour area are determined in the mobile terminal. The identification of the test strip by using the computer-readable code may be carried out at the mobile terminal by contacting a remote service using the information contained in the code, wherein the remote service may provide information about the test strip being analysed. The determining the presence or the concentration of the analyte by using the intensity or the colour of at least one reference colour in the reference colour area as a standard may be then carried out at the mobile terminal, for example by carrying out a calculation which takes into account the information obtained from the remote service. Alternatively the determination of the result may be carried out at the remote service.

In one embodiment at least one of the following is carried out in a remote networked service: -determining the intensity or the colour of a colour reaction, -determining the intensity or the colour of at least one reference colour in the reference colour area, -identifying the test strip by using the computer-readable code, and -determining the presence or the concentration of the analyte by using the intensity or the colour of at least one reference colour in the reference colour area as a standard.

In one embodiment the obtained photograph is uploaded to the remote networked service. The intensity or the colour of a colour reaction and the intensity or the colour of at least one reference colour in the reference colour area are then determined in the remote networked service. Also the identification of the test strip by using the computer-readable code may be carried out at the remote service. Further the determining the presence or the concentration of the analyte by using the intensity or the colour of at least one reference colour in the reference colour area as a standard may also be carried out at the remote service. The final results may be the provided to the mobile terminal. The final results may be presented in the software, or alternatively a web page may be opened presenting the final results. Also other information may be provided and presented, such as statistical information, reference values relating to the current test, analysis of the results, further advices, or other information. Also graphs or tables may be presented. The networked service may provide more computing resources than a mobile terminal, and the use of the networked service may reduce network traffic, enable integration of the results with databases, save time, provide and process further information etc. In general many functions may be carried out at a remote service and practically the final results may be provided and/or transferred to the mobile terminal.

In one embodiment the information associated with the computer-readable code is used for determining the presence or the concentration of the analyte.

In one embodiment the method comprises -accessing a hyperlink, such as a URL, contained in the computer-readable code directing to a networked service providing test strip specific information, such as a lot identifier, test identifier and/or reference colour information, and -using the test strip specific information to determine the presence or the concentration of the analyte.

Accessing the hyperlink or the URL refers to opening the link contained in the computer-readable code, such as directing to a web address, and accessing the content referred to in the link, such as opening a web page. The content of the web page may be shown in the mobile terminal, of information may be downloaded from the URL to the mobile terminal to be used by the software, for example for calculating the test results or to be presented by the software.

In one embodiment the method comprises -accessing a hyperlink, such as a URL, contained in the computer-readable code directing to a networked service providing test strip specific information, and -showing said information on the mobile terminal.

In one example the URL or the hyperlink directs to a networked service which displays on a www page the results of the current measurement. In one example the service has been provided with raw information concerning the measurement, such as the obtained photograph and the test strip information, and the service has analysed the photograph and calculated the results for the current test using the test strip specific information. In one example the service has been provided with analysed information concerning the measurement, such as the analysis of the photograph, carried already at the mobile terminal, and the test strip information, and the service has calculated the results for the current test using the test strip specific information. Instead of displaying an www page, the corresponding information may be downloaded to the mobile terminal and presented in the user interface of the software. A networked service contains one or more servers arranged to run one or more software to carry out the required steps, such as one or more of the steps described above. The networked service may be connected to a database containing information about the test strips, for example on a batch level or on individual test strip level. The networked service may also maintain a database collecting information from the measurements carried out by one or more users, such as photographs or processed images, metadata related to the photographs, such as geographical data, timestamp or other metadata contained in the photograph, measurement results, user provided data, user-related data etc. The networked service may be arranged to process the measurement data and to provide processed data as a feedback to the user, for example to provide results from the measurement.

The test strip will be now explained with references to the attached figures.

Figure 1 shows an example of a multi-layered test strip 10 having a topmost removable cover layer 16, which is attached only partially to a liquid impermeable top layer 11 having an aperture 17 for applying the sample. The attached part covers the aperture or sample well 17 to provide a hermetically sealed strip to prevent any contamination entering the strip before the use and keeping the reagents intact. When the strip is to be used, the cover layer 16 will be pulled away from the test strip 10. The removable cover layer 16 may have a release layer, such as a silicone layer, to enable easy removal of the release layer from an adhesive on the top layer 11. In another example the release layer is on the top layer 11 side and the adhesive is on the cover layer 16 side.

Figure 2 shows a view of the cover layer 16 from above. The line 25 divides the cover layer 16 into two parts wherein the other part is attached to the test strip by an adhesive, and the other part enables pulling the cover layer 16 away.

The liquid impermeable top layer 11 having an aperture 17 for applying the sample is below the cover layer 16. Figure 3 shows a view of the liquid impermeable top layer 11 from above. In this example the aperture 17 is round and near the one end of the test strip. The test strip has a width a of 1.25 cm and a length b of 6.0 cm, which are the same for all the stacked layers 11, 12, 13, 14, 15. The aperture has a diameter of 3.5 mm and it is located 1.25 cm from the end of the strip. The thickness of the liquid impermeable top layer 11 is 60 pm and it is made of acrylic film 3M 467MP having an adhesive layer on the lower side. The liquid impermeable top layer 11 is printed to obtain a logo, background colour and the label of the test 24 on to the strip.

Under the liquid impermeable top layer 11 there is a second liquid impermeable layer 12, which has an aperture containing a piece of sample pretreatment material in a sample pretreatment area 18, which forms a sample pretreatment layer (Figure 4). The diameter of the aperture and the sample pretreatment are is 5.0 mm, and the sample pretreatment material is Whatman 595 filter. The center of the aperture 17 and the sample pretreatment area 18 is located 1.25 cm from the end of the strip and the aperture is therefore aligned to form a sample path 23 through the test strip 10. The thickness of the second liquid impermeable top layer 12 is 180 pm and it is made of acrylic film 3M 467MP having an adhesive layer on the both sides.

Under the second liquid impermeable layer 12 there is a non-transparent liquid impermeable layer 13 which contains at least one liquid-permeable portion 26 defining a measuring area 19 (Figure 5). The non-transparent liquid impermeable layer 13 is the third liquid impermeable layer. The liquid-permeable portion contains four holes 26 with a diameter of 0.6 mm. Also the measuring area is aligned on the sample path 23 through the test strip 10. The thickness of the non-transparent liquid impermeable layer 13 is 100 pm and it is made of white PET film.

Under the non-transparent liquid impermeable layer 13 there is a fourth liquid impermeable layer 14, which has an aperture containing a piece of reaction matrix material containing reagent in a reaction area 20, which forms a reaction layer (Figure 6). The thickness of the fourth liquid impermeable layer 14 is 180 pm and it is made of acrylic film 3M 467MP having an adhesive layer on the both sides. The reaction matrix material is pH indicator paper and the diameter of the aperture and the reaction area 20 is 5.0 mm.

Under the fourth liquid impermeable layer 14 there is a liquid impermeable bottom layer 15 containing a reference colour area 21 and a computer-readable code 22 associated with information related to or identifying the test strip printed on the reaction layer side (Figure 7). The location of the reference colour area is 0.75 cm from the end of the strip. The computer-readable code is black and has a size of 1.0 x 1.0 cm, and it is located at 1.75 from the same end of the strip as the reference colour area. Between the reference colour area 21 and the computer-readable code 22 there is an area 27 wherein the colour reaction is visible through the bottom layer. The thickness of the liquid impermeable bottom layer 15 is 100 pm and it is made of transparent PET film.

In one example the user has purchased a test strip according to embody-ments. The package of the test strip instructs installing the corresponding software from an application store. The user installs the corresponding software on a mobile phone. At this point the user has all the necessary to carry out the measurement. The user removes the covering strip from the test strip to reveal the sample well. The user then dips the test strip to a liquid to be analysed and the liquid enters the test strip. The colour reaction develops and the user places the test strip on a table with the bottom side up. The user runs the software on the mobile phone and aims the camera of the phone at the test strip. The software shows the camera view of the strip, the software analysed the image and search for the characteristic features of the test strip, such as the computer-readable code and/or the reference colour area. These objects are detected and the software recognizes the area defined by the computer-readable code and a reference area. This is shown in the screen of the mobile phone by framing the area. The software obtains a photograph of the area when the mobile phone is stable enough, and a signal, such as a sound, is provided for the user to indicate that the photograph has been taken. The measurement is carried out and the user is provided with the final result of the measurement. The result is obtained in a short time, and the user does not provide any information regarding the measurement. The result is stored in the mobile phone and/or to a remote server, and it is associated with the corresponding test type, time of the measurement and the user information, such as a mobile phone information or any other information, for example a user identification, which may be provided earlier to the software. The results are stored in a database which enables the user to view the results and statistics later on by logging on to the service. This may be done via the installed software or via a web page.

In another example the installed software expands the functionality of the existing camera application of the phone. For example a new menu or an addition to the existing menu is provided. The user aims the camera to the test strip to take a photograph. The image is shown on the display, and the user selects “Measurement” from the enhanced menu of the camera application. The measuring software is initiated and it acquires and analyses the image by carrying out the necessary functions.

When the user initiates the software on the mobile phone, a series of functions is carried out. In one example the image of the test strip is first digitized to obtain a still image. Meta data included in the image is stored. Examples of meta data include time, geographical location, type of the camera, photographing parameters, and the identification of the test strip. The image is positioned and all the extra data is cropped off from the image by using functions such as zooming, straightening, cropping, perspective correction etc. The image is calibrated, for example the brightness, white balance and/or colour balance are adjusted. The computer-readable code is recognized. A reference colour map is obtained and the colour values are read. The location of the colour reaction in the image is defined and the colour values are read. Any text portions or the like are recognized by using OCR. The original image or the processed image may be stored. The results are calculated and stored in a data base, for example to obtain statistics. A web report is created and provided to the user.

Claims (18)

A test strip (10) for measuring an analyte in a liquid sample, the test strip comprising: - a reaction layer (20), such as a fiber-based reaction layer, containing a reagent arranged to react with the analyte to cause a color reaction indicating the presence or concentration of analyte; ) and computer readable code (22) to which the test strip information is attached, characterized in that the test strip further comprises: - an opaque liquid impermeable layer (13) on the reaction layer (20) containing at least one liquid permeable portion (26), defining a measuring region (19), wherein said at least one fluid-permeable portion is at the outer edge of the measuring region and there is no liquid-permeable portion in the center of the measuring region. The test strip according to claim 1, comprising a liquid impermeable base layer comprising a control color region and a computer readable code to which the test strip information is attached, preferably on the reaction layer side, wherein the color reaction, the reference color and the computer readable code are visible on the strip side layer. The test strip of claim 1 or 2, wherein the opaque liquid impermeable layer is in the form of a white layer. The test strip according to any one of the preceding claims, wherein the fluid-permeable portion comprises one or more holes, such as holes having a diameter of 0.1 to 1 mm. A test strip according to any one of the preceding claims, comprising a sample pre-treatment layer, such as a fiber-based sample pre-treatment layer, on top of an opaque liquid-impermeable layer. The test strip according to any one of the preceding claims, wherein the reaction layer and / or the pretreatment layer is arranged as an opening in the liquid impermeable layer which is aligned with the measuring area in the opaque and liquid impermeable layer to form a sample passage through the test strip. The test strip according to any one of the preceding claims, wherein the fiber-based reaction layer comprises a fiber-based organic material such as cellulose, nitrocellulose, polyamide, polysulfone, polyester or polyacrylate, polycarbonate. The test strip according to any one of claims 5 to 7, wherein the fiber-based pretreatment layer comprises a fiber-based organic material such as cellulose, nitrocellulose, polyamide, polysulfone, polyester or polyacrylate, polycarbonate. The test strip according to any one of the preceding claims, wherein the liquid impermeable layer comprises a polymeric layer, such as a plastic film, for example a thermoplastic or thermosetting polymer film. The test strip according to any one of the preceding claims, wherein the computer-readable code comprises a two-dimensional bar code, such as a QR code. The test strip according to any one of the preceding claims, wherein the computer-readable code includes a hyperlink, such as a URL, that directs to a web service providing test strip specific information, such as batch identifier, test identifier, and / or reference color information. The test strip according to any one of the preceding claims, wherein the computer-readable code contains a reference color. The test strip according to any one of the preceding claims, wherein the reference color region contains more than one reference color. A method for measuring an analyte in a liquid sample, the method comprising: - providing a test strip (10) according to any one of claims 1 to 13, - providing a mobile terminal having a camera and installed software for determining the presence or concentrate of the analyte in the test strip; taking a photograph of the test strip color reaction, the reference color area (21) and the computer readable code (22) using a mobile terminal having a camera, and using the software; color or intensity of at least one reference color, - identifying the test strip by computer readable code (22) information, and - determining the presence or concentration of analyte in the determined by the intensity of the color reaction and the reference area (21) of the at least one reference color and the color intensity of a standard. The method of claim 14, wherein the mobile terminal performs at least one of: - determining a color reaction intensity or color, - determining the intensity or color of at least one reference color in the reference range, - identifying the test strip by computer readable code, and - determining the analyte presence or concentration the intensity or color of at least one reference color in the reference range. The method of claim 14, wherein the remote web service performs at least one of the following: - determining the intensity or color of the color reaction, - determining the intensity or color of the at least one reference color in the reference range, - identifying the test strip by computer readable code, and the intensity or color of at least one reference color in the reference range as standard. The method of any one of claims 14 to 16, wherein the computer-readable code information is used to determine the presence or concentration of the analyte. The method of any one of claims 14-17, wherein: - accessing a hyperlink, such as a URL, included in the computer-readable code that directs to a web service providing test strip specific information such as batch identifier, test identifier, and / or reference color information, and test strip specific information to determine the presence or concentration of analyte.