DE202004008808U1 - Instrument reading-out results of e.g. immuno assay, includes light sources and detectors to ensure velocity of fluid moving along porous lateral flow test strip lies within limits - Google Patents

Abstract

A light illuminates one of two or more separate zones on the carrier. A photodetector detects light from each zone, determining whether or not a fluid sample is present in each. A calculation circuit uses the signals to calculate the velocity of a fluid flowing along the carrier. The velocity is compared with upper and lower limits. The assay result is rejected when the velocity falls outside the limits. The sample carrier is porous. The light source is a light-emitting diode, used with a diode photodetector. Two such sources and detectors are employed. Incident and returned light are detected at each zone. Sources and detectors are each individually paired. The fluid is detected from its transmissivity, reflectivity or both. A casing encloses this apparatus. It is about 12 cm long, 2.5 cm wide and 2.2 cm high. Detector and source occupy less than a square centimeter, e.g. less than 0.7 cm 2>. Signals produced, indicate the quantity of analyte present in a zone.

Description

Environment of the invention

The The subject matter relates to assay readers for measurement of analytes. In particular, it relates to electronic readers for use with assay test strips that use optical methods for flow measurement.

background the invention

Analytical devices suitable for testing analytes at home are now widely available commercially. An immunoassay device suitable for this purpose for measuring the pregnancy hormone human chorionic gonadotropin (hCG) is sold by Unipath under the brand name CLEARBLUE ^® and is in the EP 291 194 disclosed.

The EP 291 194 discloses an immunoassay device comprising a porous support comprising: a particulate-labeled specific binding reagent for an analyte, the reagent is free to move when in the wet state; and an unlabeled specific binding reagent for the same analyte, this reagent is immobilized in a detection zone or test zone downstream of the unlabeled specific binding reagent. A fluid sample that is suspected; that it contains analyte is applied to the porous support, after which it interacts with the particulate labeled binding reagent to form an analyte-binding partner complex. The particulate marking is colored and is typically gold or a colored polymer, for example latex or polyurethane. The complex then migrates to a detection zone where it forms another complex with the immobilized unlabeled specific binding reagent, whereby the extent of the analyte present can be detected or observed. Due to the nature of the binding reactions that take place, it is necessary to wait until a certain amount of time has passed after the test has started to read the result. This is particularly important for a visual semi-quantitative test type in which the detection zone or reading line develops over time.

Various Methods for timing the result have been developed for commercial Devices proposed, including instructions to the user wait for a period of time before reading the assay result. Close other procedures a signal that is generated after a certain period of time has passed, as in our co-pending application No. PCT / EP03 / 00274 is disclosed, the signal informing the user that the Assay result should now be read.

As a control and to ensure the proper functioning of the device, a control zone is usually provided downstream of the measurement zone. A third binding reagent, capable of binding to the first labeled reagent, is immobilized in this control zone so that in the absence of analyte the user is able to check that the test has been carried out correctly. The EP 653 625 discloses a lateral flow assay test strip for use in combination with an assay reader wherein the extent of particulate label binding is optically determined. It is also from the US 5,580,794 known to provide an integrated assay device and lateral flow assay test strips, the result being determined optically using reflection measurements.

The US 5,837,546 discloses a method for automatically starting an immunoassay device wherein a lateral flow carrier is provided with additional electrodes that sense the presence of liquid on the test strip and generate a signal that turns on the sensing electronics. Due to the nature of a lateral flow type test that requires the release of a labeled particulate binding reagent, fluid flow along a support (typically porous), and trapping of the analyte complex in the detection zone, it is desirable to optimize the properties of the porous support.

The pore size of the carrier is an important aspect and is preferably selected so that it is between 1 - 12 μm. The carrier is suitably nitrocellulose, the pore size of which may vary in part due to the manufacturing process. The assay device may additionally have a wick in fluid communication with the carrier that serves to collect the liquid sample, and the carrier typically has two pieces of different materials. Nitrocellulose is typically used as the support for the assay strip and has considerable advantages over conventional strip materials such as paper because of its natural ability to bind proteins without that prior awareness is needed. To optimize the assay, the nitrocellulose is typically subjected to a number of treatments before use, including the use of blocking agents such as polyvinyl alcohol and the use of soluble glazes such as sugar to enhance the release of the labeled reagent.

The Inventors of the present invention have observed that the flow rate of liquid along the porous carrier can vary from test to test. In some cases, the wearer has a tendency to be flooded to become, i.e. the liquid front migrates along the carrier at a faster speed than normal. Was reversed in some cases noticed that the liquid front along the carrier moving at a much slower speed than normal, so the carrier In some way is blocked. It was found that the different types of liquid flow rate behavior lead to inaccurate results can.

by virtue of the inconsistent nature of the materials used for both the wick as well as the porous membrane can be used, the optimal time (after application of the Fluid sample) be variable for reading the result.

in the Interest in providing devices that are more accurate per se and more reliable are, would be it is desirable alternative or additional Provide control features that would be able to Extent and / or the speed at which the liquid sample along the porous carrier has migrated to determine and reject such measurements, if it was determined that the flow rate was outside predetermined limits falls.

It would also be desirable to provide a method in which the optimal time to read the Result reliable and could be determined repeatably.

Summary the invention

The The present disclosure provides an assay device in some embodiments ready that's a reader for use in conjunction with a lateral flow test strip has, which is able to quantitatively analyze analyte concentrations and / or qualitatively with a high degree of reliability and accuracy to eat.

The The present disclosure also provides an assay reader especially one for use in conjunction with a lateral flow test strip, as well as a method for performing an analyte measurement, wherein the extent and / or the liquid flow rate can be determined along the test strip and being the final assay result can be discarded if it is determined that the liquid flow rate outside falls below certain predetermined limits.

In some embodiments includes an assay result reading device for reading the result of a Assays performed using a liquid transport vehicle at least one light source that is capable of incidence of light on at least one of two or more spatially separate zones of the wearer to emit a photodetector arranged such that he capable is to detect light emitted from each of the two zones and generate signals indicating the presence or absence a liquid sample in the respective zone, and a calculation range that responded to the signals to the flow rate for a liquid, the along the carrier flows, to calculate the calculated flow rate with upper and lower limits, and discard the assay result, if the calculated flow rate outside the upper and lower limits.

In some embodiments includes a method of performing an assay for an analyte of interest in one fluid sample arranging a liquid carrier in the relationship to an assay result reader, one, the carrier points at least two spatially separate zones, the reader has a housing which includes at least one light source and at least one photodetector, and the carrier is arranged in such a way that the at least one light source receives light emitted on at least one of the zones, and so that light that emits from at least one of the zones onto the photodetector falls; Apply and insert the liquid sample on or in the liquid transport carrier; To calculate the flow rate the liquid sample along the beam in response to signals through the at least one photodetector are generated, indicating the presence or absence of the liquid sample displays in a respective zone; and determining whether the calculated flow rate is within predetermined acceptable limits.

The liquid transport carrier preferably has a porous carrier, such as a lateral flow assay test strip of the type well known to those skilled in the art. As an alternative to this, the liquid transport carrier can be a capillary filling chamber, channel or the like (for example as in FIG US 6,113,885 disclosed). The liquid transport carrier can be an integral part of the assay result reader, for example in the manner described in the US 5,580,794 is disclosed. In such an embodiment, the combined reader / liquid carrier would typically be disposable. Alternatively, the liquid transport carrier may be a separate component that is normally inserted into the assay result reader during the course of an assay. In this last embodiment, the liquid transport carrier (typically a lateral flow assay test strip) would generally be inexpensive and disposable after a single use, while the assay result reader would be reusable and relatively expensive.

Summary of the figures

1 FIG. 4 is a perspective view of an embodiment of an assay result reader in accordance with the present disclosure;

2 FIG. 10 is a block diagram schematically illustrating some of the internal components of the embodiment of the reader shown in FIG 1 is shown; and

3 - 5 are graphs showing different signals coming from different sections of a test stick inserted into the reader device shown in FIGS 1 and 2 is shown, introduced, and their variation over time.

detailed Description of the invention

Around To rule out doubts becomes explicit indicated that any of the features referred to herein as "preferred", "desirable", "suitable", "advantageous" or the like are described in one embodiment in combination with any other feature so described or features can be used or they can be used alone be used, except the context makes it different.

At the Describe the various embodiments are a number defined by terms as follows:

"Liquid sample" relates to either liquid Material suspected of being the analyte of interest contains. Such samples can include human, animal or man-made samples. typically, the sample is an aqueous one solution or biological fluid.

Examples for biological liquids conclude Urine, blood, serum, plasma, saliva, interstitial fluid etc., a. Other samples that can be used include water, Food products, soil extracts and the like for carrying out industrial, environmental, or food production assay as well such as medical diagnostic assays. In addition, a firm Material suspected of containing the analyte as a test sample can be used once it is modified to a liquid To form medium, which may include further treatment to release the analyte.

Everyone Suitable analyte or analytes of interest can be measured become. Analytes of particular interest include proteins, Haptens, immunoglobulins, hormones, polynucleotides, steroids, drugs, Agents infectious Diseases (e.g. of bacterial or viral origin) such as Streptococcus, Neisseria and Chlamydia, drugs and biological markers like heart markers etc., a.

typically, are the assay result readers and methods disclosed adapted to perform a diagnostic assay, i.e. for information about the health status of a single mammal (typically one human) subject.

It is preferred, the rate of progression of the liquid sample (rather than the extent of it) along the liquid carrier to calculate.

Suitably the flow rate between two zones on the liquid transport Carrier calculated so that the presence of the liquid sample in, or a passage thereof through, a first, upstream zone is detected, and also the presence of the liquid sample in, or a passage through, a second downstream zone. If the distance between the two zones is fixed and / or known, the relative or absolute flow rate of the liquid sample can be calculated simply by measuring the amount of time that elapses between the detection of the liquid sample in the first and second zones.

in principle can the first and second zones are somewhere on the liquid carrier, so could for example the first zone on the extremely upstream End, and the second zone could on the extremely downstream lying end. The distance between the two zones (and the migration time of the liquid sample) can be any that is suitable and is likely to be they depend on the nature of the analyte to be determined and the physical Dimensions and properties of the liquid carrier depends on. For example can the liquid transport carrier or several microfluidic channels which optionally have one or more different microfluids Elements such as release agents for red blood cells, time barriers or means to control the flow rate all of which affect the rate of travel of the sample become. In practice it is desirable that the two zones have a separation, so that in normal flow rates a sufficiently accurate flow rate can be calculated within the time frame of the assay Do not delay the assay process or assay result determination. For one Assay for the detection and / or quantification of the pregnancy hormone hCG, would be a desired one Time between 5 and 60 seconds, for example.

advantageously, becomes the presence of the liquid sample in, or a passage through, one or more additional Zones detected on the liquid transport carrier. This allows a more accurate calculation of the flow rate. A big number of flow velocity calculation zones can be advantageous if the acceptable range of flow rates rather narrow, or if the flow rate in different Sections of the liquid carrier vary can (e.g. if there are sections with different flow properties, for example due to the inclusion of microfluidic elements gives).

Furthermore allows a variety of "test zones" to be provided to verify that the liquid sample progress through each of the zones in the expected order, the user will see an abnormal flow pattern warned when the liquid sample in a downstream located zone before detection in a certain upstream Zone is detected. Such abnormal flow patterns can occur, for example, if a porous carrier flooded with liquid samples becomes ("excessive scanning").

If the calculated flow rate outside the predetermined acceptable limits, then the result of the assay as invalid explained become. So the flow rate calculation act as a control feature. If the calculated flow rate is too high due to flooding of the porous carrier (e.g. as a result of excessive scanning; or a result of a faulty assay device due to Defects in manufacture, or damage in storage or in of use), the user can be warned and the assay result be discarded. Likewise if the calculated flow rate is too low (e.g. due to insufficient scanning) Assay result to be discarded. For example, errors due to excessive or too little scanning can be avoided.

in principle can any property of the liquid sample be measured by the speed and / or extent of progression the liquid to calculate how its electrical capacity, conductivity or resistance. The porous carrier or other liquid transport carriers have a substance that has a detectable change in presence the liquid sample passes. For example, nitrocellulose, commonly used as a porous support in lateral flow assay strips is used is impermeable (or essentially) when dry, but its impermeability is significantly reduced after wetting. So can the measurement or detection of the change in optical reflection or transmissivity of a nitrocellulose support wetting with a liquid sample are sufficient to determine the rate and / or extent of progression the liquid sample demonstrated.

The means for calculating the speed and / or the extent of the progression of the liquid sample which are applied to the liquid transport carrier preferably have an optical detection system. Such an optical detection system typically becomes one or more signals generate (advantageously electrical signals) in a manner that responds to the speed and / or extent of progression of the liquid sample. In a preferred embodiment, a suitable optical system has at least two light sources and at least one photodetector, or vice versa, at least one light source and at least two photodetectors, in order to be able to carry out optical measurements on at least two spatially separated zones of the liquid transport carrier.

in principle can the light source outside of the assay result reader be, e.g. Ambient light. However, this is extremely likely Introduce fluctuation and it is therefore very preferred that: (a) the assay result reader is equipped with at least one integral light source (LEDs were considered special found suitable in this regard); and (b) the assay result reader with a housing or cladding that is essentially ambient light excludes entry into the interior of the reading device or at least severely limited. For the present purpose is a housing or a panel considers that it is essentially ambient light excludes if less than 10%, preferably less than 5% and most preferably less than 1% of the visible light incidence on the outside the device penetrates into the interior of the device.

On opaque synthetic plastic material such as polycarbonate, ABS, polystyrene, Polystyrene, high density polyethylene, or polypropylene, the one suitable light-blocking pigment is a suitable one Choice for the use in the manufacture of the housing. An opening can be made on the outside of the housing be provided in with the inner space inside the housing Connection is established: a test strip or similar porous carrier can through the opening introduced to perform an assay.

The fluid sample per se can have an optical property (e.g. color) that optical detection and / or monitoring of their progress accessible along the liquid carrier. For example, a blood sample will be strong in the 400 nm to Absorb 600 nm due to the presence of hemoglobin. alternative this can be done with the liquid sample before applying to the liquid carrier an easily detectable substance (e.g. a dye, fluorochrome) or similar) provided that does not interfere with the execution of the assay, but the detection (especially optical detection) of the speed and / or the extent the progression of the fluid sample facilitated.

In yet another arrangement is with the liquid transport carrier an easy-to-detect substance equipped by the liquid sample is transported. Again is a dye, fluorochrome or the like suitable in this regard. The easily detectable substance can be suitably solvable on a porous carrier or similar be immobilized so that after contact with the liquid sample can be released. The easily detectable substance can e.g. be a colored substance that does not interfere with the assay. In a preferred embodiment the easily detectable substance is a particular marker, attached to a mobile specific binding reagent (with specific Tie for the analyte) is attached, and the detection of this label in a detection zone is an essential feature of the assay.

The particulate Marker can be any that is suitable for this purpose including colored latex, a dye sol or gold particles. alternative the particulate Mark have a fluorophore that is emitted by an LED Radiation of a suitable wavelength can be excited.

The preferred optical detection system has at least one light source and at least one photodetector (such as a photodiode). Preferred light sources are light emitting diodes or LEDs. Reflected light and / or transmitted light can be measured by the photodetector. For the purposes of this disclosure, reflected light means that light from the light source is reflected from the porous support or other liquid transport support onto the photodetector. In this situation, the detector is typically provided on the same side of the carrier as the light source. Transmitted light refers to light that passes through the carrier, and typically the detector is provided on the opposite side of the carrier to the light source. For the purposes of reflectance measurement, the support can be provided with an underlayer, such as a white reflective MYLAR ^® plastic layer. Thus light falls from the light source onto the support, some is reflected from its surface and some penetrates into the support and is reflected at any depth up to and including the depth at which the reflective layer is provided. Thus, a reflection type measurement actually includes the transmission of light through at least part of the thickness of the porous support.

In one embodiment instructs the reader a housing on, in which at least two light sources (e.g. LEDs) and respective Photo detectors are included, which are arranged to light from the LED's.

A the light sources illuminate a first upstream zone on the liquid transport carrier, and another light source illuminates a second, downstream one Zone on the liquid transport carrier, and respective photodetectors are provided to detect light emitted by the respective zones are reflected and / or transmitted, the amount of such light that reflects and / or transmits will depend on whether the liquid sample (optional along with any light absorbing or light emitting Substance that is also transported) reaches the zone (s) in question Has.

In a particularly preferred embodiment instructs the assay result reader three light sources, the first, second and third zones illuminate the liquid carrier, and the flow rate the liquid sample measurements are made between at least two of the zones.

suitably is one of the zones from which measurements are made in the calculation of flow velocity are also a zone from which measurements are taken to determine the result of the assay, for example the first zone can be one Zone in which analyte-specifically labeled binding reagent is immobilized if analyte is present in the sample. A such a zone can be referred to as a test zone.

Desirably is one of the zones from which measurements in the calculation of flow velocity be made, also a zone from which control measurements for the purpose of getting a control value to be used to determine if the assay was performed correctly. Such a zone can be referred to as a control zone.

It is advantageous if there is a zone from which measurements in the Flow rate calculation which is also a zone from which measurements in the Calibration of the assay result reader. Such Zone can be referred to as a reference zone.

It is desirable if the components of the assay reader that are used in the detection and / or quantification of the analyte of interest can also be used in the Flow rate calculation the liquid be used. This gives advantages of simplicity and economy that especially for a disposable device is desirable are. In particular, a preferred assay result reader has an optical one Detection system for detecting the presence and / or the amount of the analyte of interest, and the same optical detection system is used to take measurements for the purpose of calculating flow velocities perform.

In a particularly preferred embodiment receives the assay result reader Measurements from a control zone, a reference zone and a test zone, with the control zone downstream from the reference zone, which in turn is downstream from the test zone (i.e. the reference zone lies between the test and control zones). The reference zone allows, inter alia, the measurement an optical property (e.g. reflection and / or transmissivity) of the liquid carrier, if it is wetted (e.g. a wetted porous support). Are suitable the results obtained from the test and control zones, normalized relative to the reference zone and takes this into account and compensates for any fluctuations in the optical property the sample. This is particularly important when biological samples, such as urine, used in the composition (e.g. concentration) can vary widely and therefore vary in color and color intensity.

The casing of the assay result reader typically has an opening on so that a test strip is detachable in the housing introduced and (preferably) in the housing can intervene. The housing is designed such that ambient light, which the inside of the Reading device achieved is limited to an absolute minimum. Desirably are suitable alignment and fastening devices within the housing provided so that the test strip remains in a fixed position, when he introduced is. The light sources are arranged in the housing in such a way that if the test strip is inserted correctly, the light sources correctly aligned with the respective zones to be measured are.

The assay test strip can be any conventional lateral flow assay test strip as in that EP 291 194 or US 6,352,862 disclosed. The test strip preferably comprises a porous carrier which contains a particulate labeled specific binding reagent and an unlabeled specific binding reagent holds. The light sources and corresponding photodetectors are preferably aligned such that light from the light source or sources falls onto the respective zones on the porous support during use and is reflected or transmitted to the respective photodetectors. The photodetectors generate a current that is approximately proportional to the amount of light that falls on them, which is then passed through a resistor to generate a voltage. The amount of light that reaches the photodetector depends on the amount of colored particulate marking present and thus on the amount of analyte. The amount of analyte present in the sample can thus be determined. This method of optically determining analyte concentration is described in greater detail in EP 653 625 described.

Alternatively, instead of using a test strip that has a lateral flow porous support, as in FIG EP 291 194 , a test strip with binding reagents placed in a capillary, such as that described, could be used US 6,113,885 disclosed.

Around an assay measurement using an assay result reader in accordance with To perform some of the preferred features is a test strip into the reader introduced, and a liquid sample will then added to the sampling section of the test strip. alternative this can be done with a liquid sample first be applied to the test strip and the strip will subsequently into the reader introduced. The sample travels along the porous support and reaches a first one Zone, typically the test zone. When sample is added to the strip becomes a colored particulate The marker resuspends and migrates along the carrier the liquid. If the liquid front If the sample reaches the first zone, there is a reduction in the Light intensity, which reaches the photodetector instead of because of the colored particulate marking absorbs some of the light. This change in reflected or transmitted light intensity is recorded. In practice there is a larger amount of particulate marking in the initial liquid front than in the subsequent liquid present. If about that a binding reaction in the test zone due to the presence of analyte takes place, the particle marking tends to to remain in the test zone. So the shape of the resulting observed voltage-time profile depend on whether the zone is a test, Control or reference zone. For a three-zone system three voltage-time profiles for every Zone added with a time delay due to the fact that the measuring zones are spatial are separated from each other and so the time the liquid front needed to reach the first zone is less than that which is needed to reach the second, etc.

Out the analysis of the voltage-time profiles for the respective zones and Knowing the distance between zones can speed of fluid flow be determined. By using a simple algorithm the final assay measurement should be discarded when the calculated flow rate determined to be too long or too high.

In a typical embodiment the assay result reader typically continues to be one have one or more of the following: a central processing unit (CPU) or microcontroller; two or more LEDs; two or more photodiodes; a Power source; and connected electrical circuits. The power source can be a battery or any other suitable power source (e.g. a photovoltaic cell). The CPU is typical programmed to determine if a calculated speed and / or extent of Progress of the liquid sample is within predetermined limits.

suitably the assay result reader becomes a way of displaying the Show the result of the assay to the user. This can, for example take the form of an acoustic or optical signal. Desirably the device will have an optical display to show the assay result display. This can simply take the form of one or more LEDs or other light sources assume that the glow of a particular light source or a combination of light sources the necessary information transmitted to the user. Alternatively, the device can be alphanumeric or other display, such as an LCD. In addition, or as an alternative to viewing the test result display the device to the user or in any other Indicate whether the calculated speed and / or the extent of its progress the liquid sample is within predetermined acceptable limits, and thus whether the result of the particular assay should be discarded, or Not. If the reader determines that a particular assay result should be discarded, it may prompt the user to complete the assay to repeat. Displays used to display this type of information are known to the person skilled in the art and for example in the WO 99/51989.

Examples

An embodiment of an assay result reader in accordance with the present disclosure is shown in FIG 1 shown.

The reader is approximately 12 cm long and approximately 2 cm wide and is generally finger or cigar shaped. In preferred embodiments, the housing is no larger than about 12 cm long, about 2.5 cm wide and about 2.2 cm high. However, any suitable form can be used, such as a credit card reader. The device has a housing 2 formed from an opaque plastic material (e.g. polycarbonate, ABS, polystyrene, high density polyethylene or polypropylene or polystyrene containing a suitable light blocking pigment such as carbon). At one end of the reader is a narrow slot or opening 4 provided, through which a test strip (not shown) can be inserted into the reader.

The reader has two oval-shaped openings on its upper side. An opening houses the screen of a liquid crystal display 6 that displays information to the user, for example the results of an assay, in a qualitative or quantitative manner. The other opening houses an ejection mechanism 8th which, when actuated, forcefully ejects an inserted assay device from the assay result reading device.

The assay device for use with the reading device is a generally conventional lateral flow test stick, for example of the type used in the US 6,156,271 . US 5,504,013 . EP 728 309 or EP 782 707 is disclosed. The assay device and a surface or surfaces of the slot in the reader into which the assay device is inserted are shaped and dimensioned such that (1) the assay device can only be successfully inserted into the reader in the appropriate orientation; and (2) there is a precise three-dimensional alignment of the reader and an inserted assay device that ensures that the assay result can be read correctly by the reader.

A suitable assay / reader combination that shows this precise three-dimensional orientation is shown in FIG EP 833 145 disclosed.

If an assay device correctly inserted into the reader becomes a switch closed of the reader from a "sleep mode activated, which represents the normal state assumed by the reader which reduces energy consumption.

Enclosed within the housing of the reader (and therefore in 1 are not visible) are a variety of other components, which are shown schematically in 2 are shown.

With reference to 2 the reader has three LEDs 10a . b and c on. When a test stick is inserted into the reader, each LED is on 10 aligned with a respective zone of the test stick. LED 10a is aligned with the test zone, LED 10b is aligned with the reference zone and LED 10c is aligned with the control zone. Respective photodiodes 12 detect light reflected from the different zones and generate a current whose intensity is proportional to the amount of light incident on the photodiodes 12 is. The current is converted into a voltage by a damper 14 damped and fed to an analog-to-digital converter (ADC, 16). The resulting digital signal is sent through a microcontroller 18 read.

In a simple arrangement, a separate photodiode is provided to detect from each zone (ie the number of photodiodes corresponds to the number of zones from which reflected light measurements are made). The arrangement in 2 is more complicated and preferred. Two photo diodes 12 are provided. A photodiode detects light that is reflected from the test zone and some light that is reflected from the reference zone. The other photodiode 12 detects some of the light reflected from the reference zone and the light reflected from the control zone. The microcontroller 18 switches the LED's 10 one by one so that only one of the three zones is illuminated at any given time - in this way, the signals generated by light reflected from the respective zones can be distinguished on a time basis.

2 still shows schematically the switch 20 , which is closed by inserting an assay device into the reader, and which the microcontroller 18 activated. Although in 2 not shown, the device further includes a power source (typically one or two button cells) and an LCD device on that on the output of the microcontroller 18 responding.

In use, a dry test stick (ie before contacting the sample) is inserted into the reader, this closes the switch 20 , which activates the reader device which then performs an initial calibration. The intensity of the light output from different LEDs is rarely identical. It is also unlikely that the respective photo detectors have identical sensitivities. Because such variations could interfere with the reading of the assay, an initial calibration is performed in which the microcontroller compares the length of time each of the three LEDs is lit so that the measured signal from each of the three zones (test, reference and control ) is approximately the same and in a suitable operating position in a linear region of the system's response profile (so that a change in the light intensity reflected from the different zones provides a directly proportional change in the signal).

To performing of the initial Eichens leads the device through another, finer oak. This excludes measuring ("Calibration value") of reflected Light intensity for every Zone during the test stick is dry, a - subsequent measurements ("Test values") are by reference name to the calibration value for the respective zones normalized (i.e. normalized value = test value / calibration value).

Around perform an assay becomes a sample receiving section of the test stick with the liquid sample brought into contact. In the case of a urine sample, the sample collection section held in the urine stream, or the urine sample will be in one container collected and the sample collection section becomes short (for about 5-20 seconds) immersed in the sample. Sampling can be done while the test stick into the reader introduced is or, less preferably, the stick can be briefly removed from the reader for sampling removed and then back into the reader be introduced.

Then be Measurements of reflected light intensity from one or more (preferably all three) of the zones started, typically after one specific measured interval after inserting the test stick in the reader. Desirably the measurements are taken at regular intervals (e.g. in between 1 - 10 Intervals of seconds, preferably in between 1-5 seconds Intervals). The measurements are taken as a sequence of many measurements over a short period (10 milliseconds or less) periods, overlapping zone by zone, carried out, causing any effects due to fluctuation in ambient light intensity that into the inside of the case of the reader penetrates, are minimized.

3 FIG. 4 is a graph showing the intensity of reflected light (arbitrary units) versus time detected from each of the three zones using a sample that does not contain the analyte of interest. The profile for the test zone is indicated by crosses, that for the reference zone by circles and that for the control zone by triangles.

considered looking at the test zone profile, there is an initial lag phase during which the liquid sample along the porous carrier emigrated. In this period of time is the amount of light that passes through the testone is reflected, essentially constant. If the Sample reaches the test zone, falls the amount of reflected light sharply decreases. This is primarily due to absorption of light through the colored particulate marking through the fluid sample is transported back. However, there is some reduction in the reflected light intensity just go back on the wetting of the nitrocellulose-porous carrier, because dry nitrocellulose more reflected.

If the liquid front over the Test zone moves, the amount of reflected light begins to increase, the colored marking is taken with the sample downstream over the Test zone transported. The reflected light intensity returns not to the original Crowd back, because of the wetting of the nitrocellulose and because of a small amount the colored particulate Mark left behind will when the liquid progresses.

in the Generally, similar ones Profiles from the reference and control zones are shown, although these are downstream from the test zone and so on. Especially that Control zone profile does not return to its original amount of reflected Light intensity back due to the development of the "control line" (i.e. deposition of colored particulate Marking in the control zone).

The 4 is essentially similar and shows the profiles that were obtained using % normalized results (ie test value divided by calculation value × 100). The profile is expressed in% of the calculated value over time. The 4 shows that normalizing the test measurements versus an initial computational measurement reduces the variation in the signal from the test, reference and control zones (although again the control zone value remains low due to the deposition of labeled reagent in the control zone).

Around the flow rate the liquid sample along the porous carrier to calculate, the exemplary reader compares the normalize Values from the test and control zones with the result of that of the reference zone was obtained in order to achieve a "relative attenuation of the reflected light intensity" (% A).

Typical% A profiles (versus time) for a sample containing a relevant analyte of interest are shown in 5 shown. A positive attenuation means that the zone in question reflects less light than the reference zone, while a negative attenuation means that the zone in question reflects more light than the reference zone.

Referring on the% A profile of the test zone it is obvious that that Test zone signal initially greatly weakened is (relative to the reference zone) when the liquid sample (with colored particular marking) has reached the test zone but has not yet reached the reference zone Has. After about The liquid sample begins for 35 seconds to reach the reference zone and this leads to a sudden Decline in relative weakening the test zone. After about The liquid front begins for 40 seconds leaving the reference zone, causing an increase in reflection the reference zone and thus an increase in the relative weakening of the Test zone. This weakens turns off and finally reaches a plateau, with a positive weakening of just under 30%, the testone has some of the colored particulate markings due to the Presence of the analyte of interest trapped in the sample.

considered to get the profile for the control zone, it is obvious that there is an initial sharp drop (negative weakening) there because the liquid sample reached the reference zone in front of the control zone. If the liquid sample begins to leave the reference zone in front of the control zone, begins the relative negative weakening in the signal from the control zone to return to zero and when the liquid samples has reached the control zone, the relative weakening becomes positive and reaches a plateau amount of about 15% due to the deposit of labeled reagent in the control zone to get a positive control result provide.

While in the present example reader with the test zone result compared to the reference zone result, it would be a useful one Alternatively, the test zone result with the control zone result to compare.

Generally the flow velocity is spoken calculated by detecting the change in reflected light intensity associated with the arrival of the liquid sample is associated in a particular zone and determining the time between the arrival of the liquid sample passes in the different zones. The flow rate becomes more precise, as described below.

The Signal in all three zones becomes independent of the position of the liquid measured on the test strip.

The signal attenuation at the test zone is regarding signal attenuation measured at the reference zone. If the liquid front on the test zone arrives, the signal attenuation will be relative to the reference zone change, because the liquid front has not yet reached the reference zone (it is downstream from the testrone). The time measurement starts when the signal weakening of the test zone relative to the reference zone larger than Is 10%. It should be noted that the value of 10% den Indicates level of confidence, including any margin of error, which is connected to the measurement reading, which in turn is different from the depends on different measurement parameters, e.g. Test strips, optics. This can vary and can be for everyone suitable value selected become.

The liquid then progresses to the reference zone, and if the signal attenuation of the control zone relative to the reference zone is greater than minus 10% (-10%), the device considers that the liquid has reached the control zone (the minus value reflects that the control zone is located downstream of the test zone). If the signal weakening of the control zone from the reference zone is greater (ie, more positive) than zero, the device determines that the liquid has reached the control zone. The time measurement by the device does not necessarily have to correspond exactly to the time at which the liquid arrives in the respective zones.

Even though in this example the reader the speed of passage of liquid between the test and control zones, it measures them with respect to the signal from the reference zone was obtained. However, the arrival of liquid could absolutely determined in the test and control zones (i.e. not by measuring regarding the reference zone).

The reader is also programmed. to indicate a test result as invalid if the liquid sample is detected in the control zone before being in the reference zone is detected because this indicates that the fluid sample is abnormal River path is followed.

Example 2

On single optical device is used to measure both the signal and the flow rate to determine. The maximum and minimum flow rates are each set at 5 and 40 s. So any sample that is longer than 40 s required rejected as too slow (which is due to insufficient scanning any sample that is faster than 5 s will be too fast discarded. The flow rate is determined by a number of factors including porosity, distance between control and test lines as well as any chemistry in the porous Stripes that can modify the flow can be affected.

The Time is determined and set to zero when the liquid reached the test line. The timer is then set and the time until the liquid the control line is reached is measured. Monitored as another control check the device that the liquid has flowed through the reference zone. Additionally, as another control feature, monitored the device also that the liquid through the test, reference and control zones have flowed in that order before it a flow rate measurement will be accepted as authentic even if it is the flow rate range of between 5 and 40 s.

In other embodiments can Of course the upper and lower flow rate limits to a wide variety of values, in accordance with special Properties of the test liquids and / or with the factors described above.

Claims (13)

Assay result reading device for reading the result an assay performed using a liquid transport vehicle, the device comprises: at least one light source capable of Incidence of light on at least one of two or more, spatially separated Zones on the support to emit; a photo detector arranged so that he capable is to detect emitted light from each of the two zones and generate signals indicating the presence or absence a liquid sample display in the respective zone; and a calculation circle, that responds to the signals to: the flow rate for a liquid, the along the carrier flows, to calculate; the calculated flow rate with upper and compare lower limits; and discard the assay result, if the calculated flow rate outside the upper and lower limits. Device according to claim 1, the carrier a porous carrier having. Device according to claim 1 or 2, wherein the at least one light source is a light emitting diode having. Device according to one of claims 1, 2 or 3, wherein the at least one photodetector is a photodiode having. Device according to one of the preceding claims, wherein the at least one light source has at least two light sources, and the at least one photodetector at least two photodetectors having. Device according to claim 5, where: the first light source is capable of incidence of light on the to emit the first zone and the first photodetector detects light, that emanates from the first zone; and the second light source is capable Incident light to emit the second zone, and the second photo detector Detects light emitting from the second zone. Device according to one of the preceding claims, wherein the at least one light source has at least two light emitting diodes has, and the at least one photodetector at least two photodiodes having. Device according to one of the preceding claims, being the signal indicating the presence or absence of a liquid sample in a zone, based on the optical reflection, the transmissivity, or both, the wearer is calculated. Device according to one of the preceding claims, which continues to be a housing has the at least one light source and the at least includes a photo detector. Device according to claim 9, the housing is not bigger than about 12 cm long, about 2.5 cm wide and approximately 2.2 cm high. Device according to one of the preceding claims, wherein the at least one light source and the at least one photodetector are arranged within an area that is not larger than about 1 Quadratrentimeter. Device according to claim 11, wherein the at least one light source and the at least one Photodetector are arranged within an area that is not is bigger than about 0.7 square centimeters. Device according to one of the preceding claims, wherein signals generated by the at least one photodetector a lot of the analyte that is present in a zone Show.