Patent Publication Number: US-2021164910-A1

Title: Lateral flow assay devices and method of use

Description:
RELATED APPLICATIONS 
     This application claims priority to Australian Provisional Patent Application No. 2018902733, filed in the name of Planet Intellectual Property Enterprises Pty Ltd on 27 Jul. 2018, entitled “Lateral Flow Assay Devices and Method of Use” and, Australian Provisional Patent Application No. 2018904261, filed in the name of Planet Intellectual Property Enterprises Pty Ltd on 8 Nov. 2018, entitled “Lateral Flow Assay Devices and Method of Use” and, U.S. Provisional Patent Application No. 62/825,492, filed in the name of Planet Intellectual Property Enterprises Pty Ltd on 28 Mar. 2019, entitled “Lateral Flow Assay Devices and Method of Use” and, the specifications thereof are incorporated herein by reference in their entirety and for all purposes. 
    
    
     FIELD OF INVENTION 
     The present invention relates to the field of testing biological or industrial samples. In a preferred embodiment the present invention relates to the field of diagnostic assays, particularly medical or veterinary diagnostic assays. In particular forms, the invention relates to qualitatively detecting the presence of or quantifying markers in a biological sample. In another form the invention relates to devices, such as cassettes and readers, for detecting results of lateral flow assays. In other forms the invention relates to improving the process of qualitatively detecting the presence of or quantifying markers in a sample. In one particular aspect the present invention is suitable for use as a diagnostic assay for home testing, point of care testing, or laboratory use. 
     It will be convenient to hereinafter describe the invention in relation to its useful effect in biological assays, however it should be appreciated that the present invention is not so limited and may have other applications, such as for testing for chemical or biological markers in industrial samples. 
     BACKGROUND ART 
     It is to be appreciated that any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the present invention. Further, the discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related art problems by the inventor. Moreover, any discussion of material such as documents, devices, acts or knowledge in this specification is included to explain the context of the invention in terms of the inventor&#39;s knowledge and experience and, accordingly, any such discussion should not be taken as an admission that any of the material forms part of the prior art base or the common general knowledge in the relevant art in Australia, or elsewhere, on or before the priority date of the disclosure and claims herein. 
     Lateral Flow Assays 
     An important field of diagnostics is the use of rapid immunodiagnostic assays to provide speed, accuracy and simplicity in the diagnosis and testing in subjects, such as testing for diseases, conditions, microbes or drugs. A common form of such an assay is a lateral flow immunoassay. 
     Lateral flow assays are immunoassay based diagnostic tests that are often configured in the form of a test strip of polymeric card to which various testing components are attached. The technology is based on a series of capillary beds, such as pieces of porous paper, microstructured polymer, or sintered polymer, each of which facilitates capillary flow of a liquid sample via capillary action. Reagents are often stored in dry form on various capillary beds. Lateral flow assays can take the form of a sandwich assay or a competitive assay, or in more recent examples, a combination of the two. 
     In use, a liquid sample, suspected of containing a predetermined analyte or marker, is applied onto a sample pad on the test strip. The sample pad acts as a sponge and holds an excess of the sample fluid. The fluid of the sample then migrates to an adjacent pad, typically named the conjugate pad, which the manufacturer has pre-loaded with reagents, often including a labelled reagent (conjugate). Alternatively, the reagents may be pre-loaded on to the sample pad itself, or mixed with the sample prior to application on to the sample pad. The reagents are rehydrated and interact with the sample and any predetermined analyte or marker, if present in the sample. The reconstituted reagents and sample fluid interact and migrate on to a third capillary bed, often porous nitrocellulose, which has been treated with capture reagents. Finally, the sample fluid enters a final porous material, commonly referred to as the waste pad, which acts as a wick to promote additional capillary act to draw the sample fluid through the lateral flow test and it also acts as a waste container. 
     In a sandwich type assay, as the sample fluid is drawn along the test strip it allows any of the predetermined analyte or marker that is present to attach to an antibody which has been conjugated to a label, such as colloidal gold, carbon, coloured labelled nanoparticles, fluorescently labelled microparticles or dyes, or enzymes. The labelled analyte is then drawn past a capture region where it attaches to a capture antibody which has been adhered to the material matrix, thus depositing a quantity of the label. Hence, the analyte is “sandwiched” between two antibodies, namely, the labelled antibody and the capture antibody. 
     In a competitive type assay, as the sample fluid is drawn along the test strip any of the predetermined analyte or marker is involved in competitive binding at the capture region inhibiting the binding of the labelled conjugate to the capture antibody. Thus, the presence of the predetermined analyte or marker results in the absence of the label at the capture region in a competitive assay (a positive test result). 
     In both sandwich and competitive assays, the capture antibodies are typically placed on the test strip forming a line that can be inspected. Inspection might occur directly by the naked eye for some test devices or indirectly, for example, when an electronic reader is used. Regions of the test strip where there are no capture antibodies are considered the background of the test strip. Lateral flow assays also often comprise a control zone or control line. For a control line, antibodies that bind the labelled conjugate antibodies are placed on the test strip to form a line. The control line is used to confirm that the reagents of the test have rehydrated from the conjugate pad and flown through the test strip, if a control line does not develop or in some cases if it does not meet a certain threshold then the test may be considered invalid, indicating to the user that the test should be repeated. 
     Lateral flow assay test strips are typically single use, relatively low cost and have low sensitivity compared to other diagnostic assays. 
     Lateral flow test strips are commonly used for home pregnancy tests which detect the level of the pregnancy hormone human chorionic gonadotropin (hCG) in urine. In recent years, single use electronic tests have been used. The levels of hCG in a pregnant woman&#39;s blood and urine rise steeply during the first trimester, and within a few weeks there is a substantial difference in hCG levels between pregnant and non-pregnant women. Thus, the presence of a large amount of hormone biomarker at the time of testing means that the required sensitivity for biomarker detection can be relatively low. In cases where a small concentration of the biomarker needs to be detected, the lack of sensitivity of lateral flow assay test strips may produce result lines that are weak and difficult to detect. 
     While lateral flow assay test strips have been used in electronic readers in the past, the fields of use are limited. In addition, the types of electronic readers used tend to be electronic bench readers that are restricted to a laboratory or testing location or environment. These bench readers are intended to be used for a large volume of tests and reader cost can be high initially. These readers tend to employ inspection techniques that involve scanning methods, photo-image based or a physical raster scan, to achieve the necessary accuracy, sensitivity and dynamic range. 
     Very low cost and disposable electronic, lateral flow readers have tended to be restricted to qualitative assays where the positive and negative conditions are well separated or distinguishable and large measurement uncertainty does not detract from the utility of the test. These very low cost electronic readers typically measure the light emission or reflection integrated across a region, where the region includes a test line or control line of interest. If more precise measurement of the strength of the test or control line is needed, then the location of the line within the region and the area of the line relative to the region&#39;s area, becomes more critical. Likewise, maximising the relative size of the signal from the line relative to the size of the signal from the entire region becomes critical and hence reducing the signal from the region in comparison with the signal from the line of interest, improves the overall signal to noise ratio of the system and improves the potential sensitivity. 
     Accordingly, there is a need for an assay method and devices that allow lateral flow assay test strip result lines to be presented in a manner that allows electronic readers to provide reliable, repeatable and accurate results. 
     There is also an ongoing need to produce assay devices that are low cost, and preferably ultimately disposable, for single use or low volume based testing. 
     In the past, efforts have been made to address these needs. For example, US patent application publication No. 2003/0017615 (Sidwell et al) teaches the addition of a dye to the lateral flow test strip to increase visual contrast between the developed result line and the background. For example, a typical colloidal gold lateral flow test strip will develop a red-purple result line on a white background. If the background were dyed to be a contrasting colour such as green, the effective visual contrast is increased. This assists visual assessment of the test strip results but may not improve assessment by electronic reader depending on the illumination source (a green background as measured with a green illumination source is effectively the same as a white background) and it requires chemical changes to the test strip which may affect chemical reactions and concomitantly, the accuracy of results. 
     U.S. Pat. No. 8,445,293 (Babu et al) teaches maximisation of binding analytes and minimisation of non-specific binding by adding a chromatographic carrier to the lateral flow test strip. The carrier reduces non-specific binding in the background region, thereby increasing contrast of the result line. However, this requires changes to test strip chemistry and would incur additional costs. 
     International (PCT) patent application publication No. WO 2012/099897 (Symbolics, LLC.) relates to lateral flow assays using two dimensional features. Reagents are placed on the lateral flow test strip as dots instead of the traditional line. This creates the ability to print arbitrary shapes instead of the traditional result line. These shapes can be used in the form of words or shapes to increase the perceived contrast of the test and reduce human error or confusion. However, this innovation suffers the drawback that it would require changes to the test strip manufacturing process and would incur additional manufacturing cost. Furthermore, with respect to electronic readers, as there is no actual increase in contrast there would be no significant improvement in readability of the test strip. 
     U.S. Pat. No. 8,475,731 (Abraham et al) relates to a lateral flow assay reader having a transparent barrier insert to help to accurately align the test strip in the measurement device. However, the transparent insert requires regular cleaning or it will affect the measurement or results. Furthermore, inserting and cleaning the insert are extra process steps that increases complexity and cost of measurement. 
     U.S. Pat. No. 7,315,378 (Phelan et al) relates to a new optical arrangement for an assay reading device which includes having multiple photodetectors aligned to measure reflection from a single light source. The arrangement has the advantage that fewer light emitters are required for multiple measurement regions, but it also has the disadvantage that a different amount of light will reach each measurement region. The number of parts required leads to a lower cost, but this is at the expense of consistent performance across the measurement regions. 
     US patent application publication No. 2015/0226752 (Nazareth et al) relates to a device and method for electronic analyte assay wherein multiple light sources are aligned to illuminate a single measurement region. This provides more illumination on each measurement region, but with concomitant need for more light emitters being required for each measurement region. Thus, the increase in measurable signal comes at the cost of additional parts per measurement region. 
     Chinese patent application publication No. CN104730229 (Wandfo Biotech Co., Ltd.) discloses an electronic reader for a test strip assay detection. The apparatus as described pertains also to a system of multiple light sources with a single corresponding optical detector in the form of a photodetector. However, it is noted that the number of photodetectors is not limited to one and may be two or more, where a plurality of light detectors may receive more reflected signals and help to improve the accuracy of test results. Primarily, the disclosure is directed to an electronic detection device comprising a cassette for accommodating the test strip which has an intersected first light separator and second light separator that is in a T-shaped configuration, wherein the first separator comprises a light source separator and an anti-scatter separator. A plurality of light sources are separated into two groups by the first light source separator at the positions of the light sources. A detection region of the test strip is separated from a blank region by the second anti-scatter separator. The light sources are separated from a light detector by the second separator. The second anti-scatter separator does not contact the light detector so as to form a first transmitting gap. The second separator does not contact the test strip so as to form a second transmitting gap and rays reflected from the detection region and the blank region can sequentially penetrate through the second transmitting gap and the first transmitting gap and enter the light detector to be detected. Accordingly, the photoelectric detection device is capable of effectively preventing light interference and the accuracy of the detection result may be significantly improved. 
     U.S. Pat. No. 9,243,997 (Petruno et al) relates to a lateral flow assay system and method in which multiple measurements of subsections of the measurement region are taken. This scanning arrangement optimises reading of the result line by ensuring that only the relevant signal is analysed and all the background can be discarded. However, it requires an array of measurement sensors or moving parts so that the complexity, cost of parts and assembly costs of the scanning device is much higher than any static reader. 
     As noted in international (PCT) patent application publication No. WO 2011/048381 (SPD Swiss Precision Diagnostics, GmbH) the trend towards digitally-read devices aims to remove any element of interpretation of the result needed by the user or medical professional. These devices may be two-piece kits, the test strip being incorporated in one type of assay device such as a test stick, which is inserted into a cavity (“test bay”), as described by WO 2011/048381, of a separate reader to digitally read the assay result via optical or other reading elements. The test stick is generally a low cost, disposable element, whereas the reader is more sophisticated and may be reusable. In such kits, it is generally important to ensure that the appropriate regions of the test strip are correctly aligned with the reading elements. An extremely high level of precision of positioning is desired to maximise accuracy, especially when the assay results in the appearance of, or change in, one or more thin lines on the test strip which must be detected by the reading elements. Desirably, therefore, the kit should include features which guarantee accurate positioning of the test strip each time, even when used by an unskilled user. Accordingly, WO 2011/048381 discloses a connection assembly for a test device comprising a carriage for receiving at least a portion of a test device and a receptacle for co-operation with the carriage. The carriage is longitudinally movable with respect to the receptacle and is latchable to the receptacle at a predetermined ‘pre-reading’ position. Whilst there is brief mention of non-magnetic latching means in the form of a sprung pin or other common means known at the time, this prior art disclosure is directed towards the reader comprising magnetic means for latching the assay device onto the reader within the cavity at a predetermined reading position, said latching either being direct latching or via latching of the carriage onto the reader. 
     In another example mentioned in the preamble of WO 2011/048381, European patent publication No. EP0833145 discloses a “lock and key” location feature and combined switch actuation mechanism, that is provided inside a test bay which engages with a corresponding mating feature on the test stick. The test bay is formed by two case halves, one half being slidable and acting as a carriage to guide the test stick gently into position with the assistance of runners and an elastic band, upon application of a linear insertion force by the user. The carriage releasably clicks into place on the other case half when the test stick has been inserted the correct distance and the location features are engaged. This design is considered to be preferred for applications in which the reader is used only once or only a limited number of times, such as for pregnancy tests or ovulation tests. Wear of the device is not a major problem, but there is room for improvement in terms of the precision positioning desired, because it is subject to problems caused by slight manufacturing variations. 
     Further examples of prior art electronic lateral flow assay test devices and readers are as follows. 
     U.S. Pat. No. 9,807,543 (Zin et al) discloses a test device configured for wireless communication of the initiation of a test and wireless communication and data transfer of test results. The invention disclosed within this reference is directed to expanding the usefulness of hand-held or portable test kits, particularly with respect to data communications. 
     US patent application publication No. US 2016/0202190 (Hein et al) discloses an improved camera imaging technique for lateral flow assay tests, which is intended for increasing the speed of obtaining test results. 
     US patent application publication No. US 2010/0172802 (Sharrock et al) discloses a device for determining a test result based in part on detecting the flow rate of an analyte on a lateral flow assay test strip. The device includes a light detection system for detecting light reflected from first and second zones of the test strip including a signal indicative of an amount of analyte present and a processor for determining a result indicative of the time required for sample analyte to flow from the first zone to the second zone. 
     US patent application publication No. US 2015/0094227 (McCarthy et al) discloses a single-use pregnancy test device directed to an improved assay for detecting pregnancy by use of a combined measurement for hCG (human chorionic gonadotrophin), FSH (follicle-stimulating hormone) and a progesterone metabolite. 
     US patent application publication No. US 2016/0139156 (Lakdawala) discloses a multi-use lateral flow assay test strip reader for ovulation and pregnancy. The disclosure is primarily directed to the flexibility in operation of a base reader with different sensing heads including a lateral flow/colour change reader and a basal temperature sensing cassette. 
     US patent application publication No. US 2012/0021531 (Ellis et al) discloses a single-use lateral flow assay test reader for determining an estimate of the length of time since conception for a pregnancy test. The disclosure of the test reader is primarily directed to a comparison of assays to a stored analyte threshold for measuring levels of hCG over an extended analyte range. The reader itself as disclosed includes a first assay flow-path having a detection zone for measuring hCG in a lower concentration range and a second assay flow-path having a detection zone for measuring hCG in a higher concentration range. The assay device may include a shared reference zone, a shared control zone and each flow-path may comprise a single detection zone. It further includes a single light detector to detect light from both detection zones and four light sources to respectively illuminate the shared reference zone, the shared control zone and the two detection zones. 
     US patent application publication No. US 2012/0021531 (Ellis et al) discloses an in vivo immunoassay device for insertion to a patient&#39;s body in the form of an autonomous swallowable capsule where a chromatography strip for immunoassay of a body lumen substance is provided along with a sensor to sense a property of the chromatography strip. 
     U.S. Pat. No. 9,488,585 (Emeric et al) discloses a multi-use optical and electrochemical assay test reader. The disclosed system is adapted to read both a lateral flow and an electrochemical test on the same device. For detection, a camera reader is utilised for the lateral flow assay test. 
     US patent application publication No. US 2009/0155921 (Lu et al) discloses a multi-use lateral flow assay test reader. The disclosure is primarily directed to a scanning method in which a spring arrangement with a damper for speed control is used to transport or scan the test strip past a measurement sensor. 
     US patent application publication No. US 2012/0321519 (Brown) also discloses a multi-use lateral flow assay test reader and more specifically a connection assembly for an assay test device. The disclosure is directed to providing accurate positioning of a cassette in a reader using magnets &amp; other mechanical features. The connection assembly comprises a carriage for receiving at least a portion of a test device and a receptacle for co-operation with the carriage where the carriage is longitudinally movable with respect to the receptacle and is latchable to the receptacle at a predetermined position. The reader comprises magnetic means for latching the assay test device onto the reader within said cavity at a predetermined reading position. The latching is either direct latching or via latching of the carriage onto the reader. 
     The preceding discussion of background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application. 
     SUMMARY OF INVENTION 
     It is an object of preferred embodiments described herein to provide an electronic reader for lateral flow assay test strips. 
     It is an object of the embodiments described herein to overcome or alleviate at least one of the above noted drawbacks of prior art systems or to at least provide a useful alternative to prior art systems. 
     In one aspect of embodiments the invention provides an electronic lateral flow assay test reader for reading a lateral flow test strip, the electronic lateral flow assay test reader having a light guide comprising a window structure for framing a development area of the test strip, the development area comprising portions that include a test background region and at least one test result line, wherein the dimensions of the window structure are configured to maximise the proportion of the at least one test result line framed relative to the proportion of test background region framed. 
     The window structure preferably comprises individual windows for framing respective portions of the development area of the test strip such that any of the test background region framed by the window structure is minimised. 
     In preferred embodiments the test strip includes strip background and the window structure further comprises at least one window for framing strip background. 
     Preferably, the respective portions of the development area of the test strip framed by the individual windows comprises one or more of: 
     a test line; 
     a control line. 
     The reader has a housing which may be of at least two parts which alone or in combination retain reader components including: 
     the test strip; 
     a PCB incorporating test measurement components; and 
     the light guide as a separate element. 
     The light guide may be disposed in close proximity to the test strip. 
     In embodiments the electronic reader may further comprise a carrier adapted to retain reader components including a removably insertable cassette adapted for containing the lateral flow test strip. 
     In a preferred embodiment of the present invention there is provided an electronic lateral flow assay test reader for reading a lateral flow test strip, the electronic lateral flow assay test reader having a light guide comprising a window structure for framing a development area of the test strip, the development area comprising portions that include a test background region and at least one test result line, or result line(s) wherein the dimensions of the window structure are configured to maximise the proportion of the at least one test result line framed relative to the proportion of test background region framed and wherein the electronic lateral flow assay test reader is characterised by the window structure comprising individual windows for framing respective portions of the development area of the test strip such that any of the test background region framed by the window structure is minimised. 
     In a preferred embodiment the electronic reader comprises a unitary housing for releasably receiving and engaging with the carrier. 
     The window structure of the light guide may be formed by one or a combination of: 
     the carrier; 
     the cassette. 
     The electronic reader may further comprise: 
     illumination sources for illuminating the at least one test result line and the test background region of the development area of the lateral flow test strip, and; 
     measurement sensors for detecting light received from the at least one test result line. 
     Preferably, each respective illumination source is paired with each respective measurement sensor. 
     Preferably the cassette comprises: 
     a recess for receiving and nesting the lateral flow test strip therewithin, 
     at least two or more windows for framing respective portions of the development area of the test strip, the dimensions of the window being configured to maximise the proportion of at least one result line framed relative to the proportion of test background framed. 
     In preferred embodiments surfaces of the cassette comprise minimally reflective material. 
     In another aspect of embodiments, the invention provides an electronic reader for a lateral flow assay test strip, the electronic reader comprising: 
     a recess for receiving and nesting the lateral flow assay test strip therein; 
     at least one LED illumination source for illuminating one or more result lines or a test background region on the test strip; and 
     at least one illumination sensor for sensing illumination reflected from the one or more result lines on the test strip, 
     wherein a current of electricity supplied to each LED illumination source is measured for detecting changes in temperature and changes in LED supply voltage during illumination of the lines on the test strip, and the changes used to calculate applied compensation. 
     Preferably, the compensation is calculated and applied by measuring the forward current prior to the start of the test, and then again after the sample has developed and the test strip is ready to measure. Furthermore, the difference in the forward currents as a ratio may be calculated in a software routine and used to compensate for temperature and voltage effects which influence the forward current between the start of the test and when the sample is ready. The electronic reader may be operably associated with a voltage source arrangement used to power the at least one LED. 
     In a further aspect of embodiments, the invention provides an electronic reader for a lateral flow assay test strip, the electronic reader comprising: 
     a cassette for receiving and nesting the lateral flow assay test strip therein; 
     a PCB operatively associated with a light guide and including; 
     at least one LED illumination source for illuminating test and control lines and test background regions on the test strip, and 
     at least one illumination sensor for sensing illumination received from the lines on the test strip, 
     wherein one or more of the cassette and the PCB of the reader are adapted for engagement with a unitary housing of the reader. 
     In another aspect of embodiments, the invention provides apparatus for an electronic reader of a lateral flow assay test strip, the apparatus comprising: 
     a cassette comprising a recess for receiving and nesting the lateral flow assay test therewithin; 
     at least one LED illumination source for illuminating result lines and test background regions on the test strip, and; 
     illumination sensors for sensing illumination received from the result lines on the test strip, 
     wherein the cassette is removably retained within the reader by a retention mechanism. 
     In preferred embodiments the retention mechanism is formed by parts of one or a combination of the reader, the cassette and a carrier accommodating the cassette for engagement with the reader and the retention mechanism is adapted to align individual windows of one or a combination of the cassette and the carrier wherein the aligned windows frame respective portions of a development area of the test strip. 
     The retention mechanism may comprise a snap fit mechanism residing upon or within the cassette and/or the reader including one or more of: 
     snap fingers for retaining the cassette in place within the reader, and; 
     biasing means which assists in releasing the cassette from the reader, 
     which are adapted to work together to ensure that the cassette is positioned consistently and correctly in the reader. 
     Preferably, the snap fingers reside on the cassette and the biasing means resides on the carrier or the reader. 
     Preferably, the biasing means comprises leaf springs that urge the cassette towards the electronic components of the reader used for measuring. 
     In a preferred embodiment, the reader comprises a self-closing door that prevents contaminants from entering a cavity of the multiuse reader when a cassette is not installed in the multiuse reader. The door acts to align the cassette within the reader. 
     The retention mechanism described herein may further comprise retention clips that are operatively associated with the light guide. 
     An alignment pin may be provided for engaging one or more of: 
     the reader; 
     the light guide; 
     the cassette; 
     the carrier. 
     Preferably, the reader is operable with the cassette by one of: 
     a slide-on mechanism; or 
     a clip-on mechanism. 
     In another aspect of embodiments, the invention provides an electronic reader for a lateral flow assay, the electronic reader comprising, 
     a recess for receiving and nesting a lateral flow assay test strip therein; 
     at least one LED illumination source for illuminating one or more result lines and test background regions on the test strip, and illumination sensors for sensing illumination received from the one or more result lines on the test strip; 
     input/output (IO) pins wherein each pin is operatively associated with two or more LEDs of the reader. 
     A combination of charlieplexing and multiplexing may be used to control the two or more LEDs. The two or more LEDs may be controlled from five digital IO pins. In preferred embodiments, only a single LED is powered at once. 
     Further, the reader may be adapted to detect the presence/absence of a cassette containing the lateral flow assay test strip. Moreover, the reader may be adapted to detect the presence/absence of a cassette containing the lateral flow assay test strip using the LEDs and sensors and one or more threshold signals detected where a first measured signal corresponds to a cassette is present and a second measured signal corresponds to a cassette is not present. 
     In another aspect of embodiments, the invention provides a lateral flow assay test system comprising an electronic reader as disclosed herein or the apparatus as disclosed herein. 
     In yet another aspect of embodiments the invention provides a method of assessing result lines of a lateral flow assay test strip comprising the steps of: 
     inserting the assay test strip into an electronic reader as disclosed herein or the apparatus as disclosed herein; and 
     initiating the illumination source of the electronic reader and detecting illumination received from result lines on the assay test strip. 
     In still another aspect of embodiments the invention provides an electronic lateral flow assay test reader for reading a lateral flow test strip having a development area, the development area comprising portions that include a test background region and at least one test result line, the electronic lateral flow assay test reader comprising: 
     a cassette for retaining the test strip and a carrier adapted to removably retain the cassette therein; 
     at least one illumination LED operably associated with one or a combination of the cassette and the carrier for illuminating the test strip, and; 
     a light guide comprising a window structure to direct the light emitted from the at least one illumination LED to a selected portion of the development area of the test strip, wherein the window structure is formed by: 
     one of the cassette or the carrier, or, 
     a combination of the cassette and the carrier so as to split the light guide between the cassette and the carrier. 
     The electronic reader may be further characterised by the window structure of the light guide framing the development area of the test strip by the dimensions of the window structure being configured to maximise the proportion of the at least one test result line framed relative to the proportion of test background region framed. 
     The electronic reader may also be further characterised by the window structure comprising individual windows for framing respective portions of the development area of the test strip such that any of the test background region framed by the window structure is minimised. 
     In preferred embodiments of the electronic reader a shallow recess is provided between windows of the cassette and the carrier to avoid direct contact therebetween. 
     In yet another aspect of embodiments the invention provides an electronic lateral flow assay test reader for reading a lateral flow test strip having a development area comprising a test background region and at least one test result line, the electronic lateral flow assay test reader comprising: 
     a cassette for retaining the test strip and a carrier adapted to removably retain the cassette therein; 
     at least one illumination LED operably associated with one or a combination of the cassette and the carrier for illuminating the test strip, and; 
     a light guide comprising a window structure of one or a combination of the cassette and the carrier to direct light emitted or reflected from a selected portion of the development area of the test strip to a sensor wherein the proportion of the at least one test result line relative to the proportion of test background region in the selected portion of the development area of the test strip is maximised. 
     In yet another aspect of embodiments the invention provides a cassette suitable for a lateral flow assay electronic reader, the cassette comprising, 
     a recess for receiving and/or nesting a lateral flow test strip, 
     at least one window for framing a development area of the test strip when nested in the recess, the dimensions of the window being configured to maximise the proportion of at least one test result line of the development area framed relative to the proportion of a test background region of the development area framed, 
     wherein the surfaces of the cassette comprise minimally reflective material. 
     In yet another aspect of embodiments the invention provides an electronic reader for a lateral flow assay test strip, the electronic reader comprising,
         an opening for receiving the lateral flow assay test strip, preferably a cassette containing the lateral flow assay test strip,   at least one LED illumination source for illuminating a portion of a development area or a strip background region on the test strip and   at least one illumination sensor, for sensing illumination reflected or emitted from the portion of the development area on the test strip,   wherein the portion of the development area is one of a test line or a control line, on the test strip,
           wherein a current of electricity supplied to each LED illumination source is measured for detecting changes due to LED die temperature and changes in LED supply voltage during illumination of the lines on the test strip, and the changes used to calculate applied compensation.   
               

     In another aspect of embodiments, the invention provides an electronic reader for a lateral flow assay test strip, the electronic reader comprising,
         an opening for receiving the lateral flow assay test strip, preferably a cassette containing the lateral flow assay test strip,   a PCB mounted on a carrier and including;
           at least one LED illumination source for illuminating a portion of a development area or a strip background region on the test strip, and   at least one illumination sensor, for sensing illumination reflected or emitted from the illuminated portion of the development area on the test strip,
 
wherein the illuminated portion of the development area is one of a test line or a control line on the test strip, and wherein each illumination source is paired with one illumination sensor.
   
               

     Another aspect of embodiments provides an electronic lateral flow assay test reader for reading a lateral flow test strip, the electronic lateral flow assay test reader having a light guide comprising at least one window structure for framing a development area of the test strip, the development area comprising a test background region and at least one test result line, wherein the dimensions of the window structure are configured to maximise the proportion of the at least one test result line framed relative to the proportion of test background region framed. 
     Another embodiment provides a carrier of the reader which is adapted for engagement with a unitary housing of the reader and the carrier includes a window structure as disclosed herein. 
     In a preferred form, the test strip comprises masking features printed directly on its surface to isolate a result line from the test background region of the test strip. The test strip may then be inserted directly into the reader or into a cassette that is placed into the reader. 
     Alternatively, the test strip is inserted into a cassette, with the at least one window residing on the cassette. 
     The test result may be derived from the presence or absence of one or more test lines, determined by the presence or absence of a biomarker in the sample being tested, and/or a control line. Typically, the development area of the test strip would comprise at least one sample test line and at least one control line. The test strip may also comprise at least one strip background region. 
     Preferably the cassette comprises at least two windows for framing two or more portions of the development area of the test strip. The cassette may comprise two, three, four, five, six or seven windows, wherein each window frames a separate portion of the development area of the test strip. Equally, the cassette may comprise at least two windows for framing two or more respective development areas of the test strip, which provide for multiple test lines. 
     Preferably the cassette windows are aligned side by side along the length of the test strip. 
     In one embodiment, the cassette comprises one or more windows for separately framing one or more test result lines respectively, wherein the dimensions of each of the windows is configured to maximise the proportion of a test result line framed relative to the proportion of test background framed. In addition, the cassette may also comprise one or more windows for framing one or more control lines respectively, wherein the dimensions of each of the windows is configured to maximise the proportion of a control line framed relative to the proportion of test background framed. The cassette may also comprise at least one window for framing at least one strip background area of the test strip. 
     In a preferred embodiment, the dimensions of the cassette windows are configured such that the width of the window is equal to the width of the test or control line plus the tolerances of manufacture of one or a combination of the test strip and cassette. In this respect, the tolerances of manufacture may include the sum of the tolerance of the test line width, the tolerance of test line positioning on the test strip, the tolerance of test strip nesting in the cassette recess, and the tolerance of the window width. 
     Preferably, the electronic reader comprises at least one LED illumination source and at least one illumination sensor wherein each of the illumination source and illumination sensors are paired together. 
     Preferably, the carrier of the reader is adapted for engagement with a unitary housing of the reader. Typical lateral flow readers of the prior art include a housing comprising two or four parts that are fitted together rather than a unitary housing. Advantageously, the unitary housing reduces part inventory, complexity, assembly time, and provides mechanical protection for the PCB and carrier retained inside. In addition, as there is no seam in the unitary housing, the ingress of external ambient light into the reader is reduced ameliorating adverse effects on detection of the illumination sensors. 
     Preferably, the carrier provides a mount for the PCB and comprises windows. The carrier windows are configured to act as a light guide alone or in combination with the cassette windows when a cassette is inserted into the reader, such that only the light reflected or emitted from the test strip limited to the portion of the development area framed by the carrier and cassette windows and illuminated by the paired illumination LEDs is measured by the measurement sensor. 
     When the carrier windows are correctly aligned with the cassette windows, regions of the strip are able to be illuminated and are measurable by the paired illumination LED and measurement sensor. Essentially, the aligned carrier and cassette windows performs a masking function. The present inventors have found that separation or sharing of the masking function between the carrier windows and cassette windows allows the tolerance stack for positioning of the test line and control line within an area framed for measurement (the illuminated and measurable area) to be minimised. As a result, the present inventors have found that the test and control lines can be more accurately and repeatably positioned within separate and smaller windows when the windows are part of the cassette. Separate and smaller windows allowed the inventors to maximise the proportion of a test or control line framed relative to the proportion of background framed within the window, increasing the signal to noise ratio. In addition, by separating the light guide function into two parts, the masking features of the cassette windows can be placed closer to the test strip surface and the carrier windows (including the separator) can extended towards the PCB surface, to surround and separate the illumination LEDs from the measurement sensors. This in turn reduces the tolerance stack. The cassette windows may prevent regions of the strip such as the edges from being measured. In this regard, the cassette window is arranged to mask the sides of the test strip so as to minimise exposure of the amount of the strip that contains non-uniform non-specific binding. 
     Another advantage of separating the light guide function between the carrier and the cassette is that the carrier windows (including the separator) can extend towards the PCB surface to surround and separate the illumination LEDs from the measurement sensors, whilst allowing for other masking features to be placed in close proximity to the lateral flow strip as part of the cassette windows. The carrier windows act to reduce the light from an illumination LED reaching neighbouring regions on the test strip and reflecting back to the sensor of a LED/sensor pair. In addition, the carrier windows are designed to minimise the illumination and measurement of reflected light from the cassette windows and cassette surface, reducing interfering signal noise. A preferred embodiment of the present invention locates an outer frame for the window close to the strip (the cassette window) and locates a secondary frame close to the LED and sensor (carrier window). 
     In one embodiment, each carrier window comprises a LED window and a sensor window separated by a barrier (or separator) which prevents the light from the illumination LED from reaching the measurement sensor directly, allowing for the measurement of the reflected or emitted light from the test strip. 
     In still yet a further aspect of embodiments described herein there is provided an electronic reader for a lateral flow assay test strip, the electronic reader comprising,
         an opening for receiving a lateral flow assay test strip, preferably a cassette containing the lateral flow assay test strip,   at least one LED illumination source for illuminating a portion of a development area on the test strip, and,   at least one illumination sensor, for sensing illumination reflected or emitted from the illuminated portion of the development area on the test strip,   wherein the illuminated portion of the development area is one of a test line, a control line, or a strip background region on the test strip,   wherein the cassette is removably retained within the reader by a snap fit mechanism       

     The elements of the snap fit mechanism may reside upon or within the cassette and/or the reader and their assistance with alignment of the cassette within the reader contributes to consistent and correct measurements. 
     In yet another aspect of embodiments described herein there is provided an electronic reader for a lateral flow assay, the electronic reader comprising,
         an opening for receiving a lateral flow assay test strip, preferably a cassette containing the lateral flow assay test strip,   at least one LED illumination source for illuminating a portion of a development area on the test strip, and   at least one illumination sensor, for sensing illumination reflected or emitted from the portion of the development area on the test strip,   wherein the portion of the development area is one of a test line or a control line,   wherein the reader further comprises input/output (IO) pins where each respective IO pin is operatively associated with two or more LEDs of the reader.       

     The electronic architecture of embodiments of the present invention allows the use of a greater number of measurement positions and user feedback LEDs than are usually provided with low cost microcontrollers of the prior art. Typically, in prior art each IO pin controls a single LED. A preferred embodiment of the present invention instead uses a combination of charlieplexing and multiplexing to control multiple LEDs (e.g. twelve, six user feedback LEDs and six illumination LEDs) from five digital IO pins. While this configuration has the apparent drawback of only a single LED being powered at once, it has the advantage of predictable and low current draw from the battery. Herein below, there is description of how rapid switching of the user feedback LEDs can be used to give the appearance of multiple LEDs being on simultaneously. 
     The reader comprises a user feedback system to communicate with the user. The user feedback system can be used to communicate the state of the reader to the user (such as cassette inserted, test in progress or test complete), communicate the test result and/or the validity of the test. Preferably, the user feedback system comprises a plurality of user feedback LEDs, wherein the LEDs are used as indicators to communicate to the user. Alternatively, the user feedback system may comprise an LCD screen for displaying the result and/or communicating the state of the reader with the user. 
     Optionally, the user feedback system comprises connectivity elements, such that the reader can communicate to an external device. The external device may be a smartphone or computer which can be used to communicate the state of the reader and/or communicate the test results. The external device may also process the information communicated by the reader and interpret the data in order to communicate the test result. Connectivity elements may include wireless connectivity such as WIFI or Bluetooth. 
     Furthermore, incorporating multiple LEDs into the lateral flow assay device allows the inclusion of other functionality such as a cassette presence/absence detection feature. The following feature can be implemented using the LEDs and sensors already provided for user feedback and test measurement. When there is no cassette inserted, the light from one of the user feedback LEDs reaches the measurement region and can be detected by one or more of the measurement sensors. When the cassette is inserted, the user feedback LED light is blocked by the cassette and does not reach the one or more measurement sensors. This way the user experience is improved by reducing the number of required interactions prior to performing a test. This user feedback is implemented in software without any additional components. 
     In another embodiment, the reader comprises a normally open reset switch, wherein the switch is located inside the reader and is activated when a cassette is inserted or removed. This allows the reader to be in a low power state until a user interacts with it by inserting or removing a cassette, decreasing the power consumption requirement. This increases the shelf life of the reader and permits a lower capacity, less expensive battery to be used. 
     A combination of the reader reset switch and the cassette detection features can be used in software to determine what the user intends to do. For example, if the reset switch is toggled and a cassette is detected, it is likely that the user has inserted a cassette and intends to start a test. The alternative scenario is if the reset switch is toggled and there is no cassette detected, then it is likely that the user has just removed a cassette, the powered-on reader can now continue to perform functions such as displaying the result of the previously completed test or maintaining communication with an external device. 
     In a further embodiment, an aforementioned embodiment of the lateral flow assay electronic reader of the present invention is combined with the aforementioned cassette. 
     Preferably the snap fit mechanism comprises biasing springs associated with the reader carrier and snap fingers on the cassette which work together to ensure that the cassette windows substantially align with the carrier windows. Preferably, the result lines of the test strip are centred in respect to the substantially aligned carrier and cassette windows to ensure that illumination and measurement of the signal at the test and/or control line is optimised. The biasing springs associated with the reader carrier and snap fingers on the cassette work together wherein the biasing means pushes the cassette out towards the opening and snap fingers on the cassette stop the cassette from leaving the reader. The retaining or retention mechanism holds the cassette in place within the reader and aligns cassette and reader features. This ensures correct and consistent readings. 
     The cassette is removably retained within the reader, such that the snap fingers of the cassette can be depressed and the biasing means assists in releasing the cassette from the reader opening. 
     When the cassette is positioned optimally in the reader, the cassette windows may align with the carrier windows that frame the illumination LEDs and measurement sensors. 
     The present invention further provides a system comprising the cassette and the electronic reader of the present invention. 
     The present invention also provides a method of assessing result lines of a lateral flow assay test strip comprising the steps of;
         (i) inserting the cassette containing the assay test strip into a reader according to the present invention; and   (ii) applying the sample that needs to be measured onto the cassette; and   (iii) initiating the illumination source of the reader and detecting illumination reflected or emitted from the assay test strip.       

     A multiuse reader which can be used to read more than one cassette is also disclosed. In one embodiment, the multiuse reader is a self-contained unit including a reader door that prevents contaminants from entering a cavity of the multiuse reader when a cassette is not installed in the multiuse reader. Once a cassette is inserted through the opening, the reader door pivots on a hinge. Alignment features such as location pins, alignment pins, retaining clips and other features are used to align and secure the cassette within the reader. The alignment features can be present on or within the cassette, the reader or a combination of both the reader and the cassette. 
     In another embodiment, a multiuse reader clips onto a cassette via clips of the reader surrounding the cassette or sides of the multiuse reader being received within corresponding recesses on the side of the cassette. 
     In another embodiment, a multiuse reader slides onto the cassette via a set of rails present on the cassette and/or within the reader itself. 
     Other aspects and preferred forms are disclosed in the specification and/or defined in the appended claims, forming a part of the description of the invention. 
     In essence, embodiments of the present invention stem from the realisation that the level of sensitivity of detection of lines in the development area of an assay test strip can be improved by one or more electronic, mechanical and software features, which work adequately in isolation but provide significantly better results when used in various combinations. 
     Advantages provided by the present invention in comparison to the prior art comprise the following:
         improvement in reader performance, avoiding the need for adjustment of test strip chemistry,   improvement in sensitivity,   reduction of background noise with increased resolution of measurable test results,   improved alignment and positioning of result lines relative to electronic reader measurement area;   the cassettes are disposable, low cost to manufacture and assemble,   the readers are ultimately disposable, for single use or low volume based testing, and are low cost to manufacture and assemble,   the reader is of simple configuration yet provides reduced energy consumption when not in use,   Reduction in signal from areas not directly associated with the region being measured leads to improved sensitivity   Improved alignment and positioning of result lines leads to improved accuracy.   Improved isolation between measurement regions allows simple extension to support additional result lines.   Improved use of processor I/O resources allows simple and low-cost expansion to support additional result lines.   A low-cost technique for driving and correcting LED performance.       

     Further scope of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure herein will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further disclosure, objects, advantages and aspects of preferred and other embodiments of the present invention may be better understood by those skilled in the relevant art by reference to the following description of embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the disclosure herein, and in which: 
         FIG. 1  illustrates a typical lateral flow test strip of the prior art; 
         FIG. 2A  and  FIG. 2B  are exploded and assembled illustrations of a preferred embodiment of the present invention, respectively; 
         FIG. 3  illustrates an exemplary cassette containing an assay test strip in accordance with an embodiment of the present invention where  FIG. 3A  shows a cassette comprising a plurality of windows and  FIG. 3B  shows a single cassette window with masking features directly on the test strip; 
         FIG. 4  illustrates a cassette window configured to a test result line in accordance with an embodiment of the present invention; 
         FIG. 5  illustrates the framing of test result lines of a test strip by cassette windows in accordance with embodiments of the present invention, where  FIG. 5A  and  FIG. 5B  show acceptably framed test result lines and  FIG. 5C  shows an unacceptable framing of a test result line; 
         FIG. 6  is a side sectional view of a PCB mounted on a carrier in accordance with an embodiment of the present invention; 
         FIG. 7A  is a bottom sectional view of a cassette showing a PCB mounted on a carrier in accordance with an embodiment of the present invention,  FIG. 7B  is a detail view of the measurement area of the carrier; 
         FIG. 8A  is a top view of a cassette inserted into an opening in a carrier, and  FIG. 8B  is an in-section view showing the cassette of  FIG. 8A  with test strip nested therein and inserted into the reader carrier in accordance with an embodiment of the present invention; 
         FIG. 9  is a plot of measured attenuation against test line intensity comparing the performance of black and white cassettes with the reader according to an embodiment of the present invention; 
         FIG. 10  is a section view illustrating operation of a cassette in association with a reader of according to an embodiment of the present invention where  FIG. 10A  shows an open reset switch,  FIG. 10C  shows a closed reset switch and,  FIG. 10B  shows a reset switch re-opened on removal of the cassette from the reader; 
         FIG. 11  is a schematic electronic circuit diagram illustrating a basic arrangement of LEDs according to preferred embodiments of the present invention; 
         FIG. 12  is a table showing charlieplexing and multiplexing control, respectively, for a varying number of loads as a function of the number of available I/O pins utilised in a reader according to a preferred embodiment of the present invention; 
         FIG. 13  shows another embodiment of a reader of the present invention for detection of the presence of a cassette inserted in a carrier ( FIG. 13A ) and for detection of the absence of a cassette inserted in a carrier ( FIG. 13B ). 
         FIG. 14A  is a cross sectional view of a cassette and strip inserted within a multi-use reader carrier in accordance with an embodiment of the present invention, illustrating that the light guide function is separated between the carrier and the cassette.  FIG. 14B  is a detailed view of the cross section of  FIG. 14A  showing illumination paths associated with an illumination LED and measurement sensor pair for a portion of the development area of the test strip.  FIG. 14C  illustrates the respective areas of the test strip that are illuminated and measurable in accordance with the embodiment of  FIG. 14A . 
         FIG. 15A  and  FIG. 15B  are exploded and assembled illustrations, respectively, of a single use version of a preferred embodiment of the present invention where the test strip is contained in the reader without a cassette or carrier as such, and in which the top and bottom housing may be considered to serve the function of a carrier. 
         FIG. 16A  and  FIG. 16B  are section views showing an overlay of the LED and sensor locations on top of the carrier and cassette assembly.  FIG. 16C  is a detailed view of the cassette inside the carrier and  FIG. 16D  is a detailed view of the carrier only. 
         FIG. 17A  and  FIG. 17B  are 3D section views illustrating a cassette fully inserted into a carrier and the reset switch on the PCB. 
         FIG. 18A  and  FIG. 18B  are side section views of a cassette inserted in a carrier showing the alignment of the cassette windows and the carrier windows. 
         FIGS. 19A, 19B, 19C and 19D  are different views of a multiuse reader for use with a cassette assembly, with  FIGS. 19B, 19C, and 19D  showing sectional views of the multiuse reader. 
         FIG. 20A  and  FIG. 20B  show a multiuse reader and a close-up view of a reader door in the closed and open positions respectively. 
         FIG. 21  shows a sectional view of a multiuse reader with an inserted cassette. 
         FIG. 22A  and  FIG. 22B  show a sectional view of the cassette in a multiuse reader. 
         FIG. 23A  and  FIG. 23B  show closeup views of a printed circuit board assembly. 
         FIG. 24A  and  FIG. 24B  are schematic electronic circuit diagrams illustrating a simplified architecture to drive a multiplexed LCD arrangement. 
         FIG. 25  shows a top down sectional view of a multiuse reader with an inserted cassette with the top removed. 
         FIG. 26  shows a sectional view of the cassette within a multiuse reader. 
         FIG. 27A  and  FIG. 27B  are sectional views of a multiuse reader receiving a cassette and being aligned within a multiuse reader. 
         FIG. 28A  and  FIG. 28B  show a blood collection unit blocker on a multiuse reader. 
         FIG. 29A  to  FIG. 29D  show views of a cassette with a reader which is slid on. 
         FIG. 30A  and  FIG. 30B  show views of a clip-on multiuse reader attached to a cassette. 
         FIG. 31A  shows a sectional view of a clip-on multiuse reader attached to a cassette. 
         FIG. 31B  shows a closeup view of a locating pin of the clip-on multiuse reader. 
         FIG. 32A  shows a clip-on multiuse reader. 
         FIG. 32B  shows a partial sectional view of a clip-on multiuse reader. 
         FIG. 33  shows an exploded view of a clip-on multiuse reader without a reader cover. 
     
    
    
     DETAILED DESCRIPTION 
     The following is a component list for figure reference numerals as depicted in the accompanying drawings: 
     
       
         
           
               
             
               
                   
               
             
            
               
                 Biological sample 1 
               
               
                 Sample pad 2 
               
               
                 Direction of flow 3 
               
               
                 Conjugate pad 4 
               
               
                 Test result line 5 
               
               
                 Background region 6 (which may include both strip background and 
               
               
                 test background) 6 
               
               
                 Control line 7 
               
               
                 Development area 8 
               
               
                 Nitrocellulose membrane 9 
               
               
                 Waste pad 10 
               
               
                 Backing card 11 
               
               
                 Cassette top 12 
               
               
                 Test strip 13 
               
               
                 Cassette bottom 14 
               
               
                 Cassette assembly 15 
               
               
                 PCB 16 (Printed Circuit Board) 
               
               
                 Carrier 17 
               
               
                 Reader opening 18 
               
               
                 Battery 19 
               
               
                 Housing 20 
               
               
                 User feedback LEDs 21 
               
               
                 Sample port 22 
               
               
                 Snap fingers 23 
               
               
                 Cassette window structure 24 
               
               
                 Direct masking 25 
               
               
                 Viewing area 26 
               
               
                 Activation recess 27 
               
               
                 Width of test result line 28 
               
               
                 Combined tolerance for test result line 29 
               
               
                 Width of window 30 
               
               
                 Height of window 31 
               
               
                 Height of test strip 32 
               
               
                 Region of non-uniform non-specific binding 33 
               
               
                 Leaf springs 34 (vertical biasing means) 
               
               
                 Lateral biasing means 35 
               
               
                 Reset spring clip 36 
               
               
                 Measurement sensors 37 
               
               
                 Illumination LEDs 38 
               
               
                 Measurement area 39 
               
               
                 Carrier windows 40 
               
               
                 Switch open 41 
               
               
                 Switch closed 42 
               
               
                 Illumination and sensor separator 43 
               
               
                 Adjacent sensor separator 44 
               
               
                 Measurement shadow 45 
               
               
                 Area framed for measurement 46 
               
               
                 Illumination shadow 47 
               
               
                 Housing top 48 
               
               
                 Housing bottom 49 
               
               
                 Light guide 50 
               
               
                 Multiuse reader 51 
               
               
                 Reader housing 52 
               
               
                 Reader housing top 53 
               
               
                 Reader housing bottom 54 
               
               
                 Output user interface 55 
               
               
                 Reader door 56 
               
               
                 Reader dock 57 
               
               
                 Door pin 58 
               
               
                 Reader door socket 59 
               
               
                 Spring clip 60 
               
               
                 Alignment recess of the door 61 
               
               
                 Locating boss 62 
               
               
                 Reader cavity 63 
               
               
                 End posts 64 
               
               
                 Spring return feature 65 
               
               
                 U-shaped recess 66 
               
               
                 Lip interface 67 
               
               
                 Door lip 68 
               
               
                 Door receiving section 69 
               
               
                 Alignment section 70 
               
               
                 Cassette 71 
               
               
                 Retention Clips 72 
               
               
                 Cassette detection switch 73 
               
               
                 Raised surface of cassette 74 
               
               
                 Cassette bump 75 
               
               
                 Channel on cassette 76 
               
               
                 Cassette top 77 
               
               
                 Printed circuit board assembly (PCBA) 78 
               
               
                 Battery terminal 79 
               
               
                 Optics components 80 
               
               
                 Thin rib 81 
               
               
                 Alignment pin 82 
               
               
                 Blood collection unit of cassette 83 
               
               
                 Blood collection tube of cassette 84 
               
               
                 Sample port of cassette 85 
               
               
                 Buffer delivery button 86 
               
               
                 Alignment boss 87 
               
               
                 Light guide 88 
               
               
                 Ramps of cassette 89 
               
               
                 Blood collection unit blocker (BCU) of reader 90 
               
               
                 Rails/rib on cassette 91 
               
               
                 Slide-on multiuse reader 92 
               
               
                 Shroud of slide-on multiuse reader 93 
               
               
                 End stop 94 
               
               
                 Cassette bottom 95 
               
               
                 Sliding feature of reader 96 
               
               
                 Clip-on multiuse reader 97 
               
               
                 Clip-on arms 98 
               
               
                 Cassette recess 99 
               
               
                 Shoulder 100 
               
               
                 Alternate clip-on reader 101 
               
               
                 Cassette with recess 102 
               
               
                 Cassette recess 103 
               
               
                 Reader bottom 104 
               
               
                 Rounded face of clips 105 
               
               
                   
               
            
           
         
       
     
       FIG. 1  illustrates a typical lateral flow test strip  13  of the prior art but which may also find use in the present invention. Lateral flow assays are immunoassay based diagnostic tests and are often configured in the form of a test strip  13  or card to which various testing components are attached. In essence, they rely on capillary flow of liquid through a membrane containing a capture reagent. 
     The illustration of  FIG. 1  depicts droplets of a biological sample  1  being dropped in the direction of the arrow  1  onto a treated sample pad  2  on a test strip  13  of polymeric backing card  11 . The adjacent pad (conjugate pad)  4  is soaked with a labelled detector reagent (conjugate), such as a gold colloid or fluorescent labelled microparticles conjugated to a detector antibody. The conjugate is reconstituted and binds any analyte in the sample if present. The conjugate and sample flows in the direction of the arrow  3  through the nitrocellulose membrane  9 , passing the capture antibodies which may eventually develop into the test line  5  and control line  7 , further indicated with a “T” and a “C”, respectively, as shown, as well as background regions  6  without capture antibodies, which may include strip background and test background and, ultimately ending at the waste pad  10 . After a predetermined amount of time, the test is deemed completed and the development area  8  is inspected to determine the test result. 
     The illustration of  FIG. 2A  and  FIG. 2B  depict the lateral flow assay electronic reader of a preferred embodiment of the present invention comprising a PCB  16  mounted on a carrier  17 , a battery  19 , encased in a unitary housing  20 . The carrier  17  contains an opening  18  which accepts a cassette assembly  15  where the cassette assembly  15  comprises a cassette top  12 , cassette bottom  14  and lateral flow test strip  13 . The PCB  16  holds user feedback LEDs that are visible through holes or apertures  21  in the carrier, as shown in  FIG. 2B . 
     The unitary housing  20  reduces part inventory, complexity, assembly time, and provides mechanical protection for the PCB  16  and carrier  17  retained inside. In addition, as there is no seam in the unitary housing  20  the ingress of external ambient light into the reader is reduced. Another advantage of a unitary housing  20  is the lack of side seams also means the ingress of external fluid from the environment, such as cleaning fluid, is reduced and the internal electronic components are protected. 
       FIG. 3  illustrates a preferred embodiment of the cassette  15  containing an assay test strip  13 .  FIG. 3A  depicts features of the cassette assembly  15 , comprising a sample port  22 , snap fingers  23 , a viewing area  26  comprising a cassette window structure  24  having a plurality of windows in this instance for isolating or masking portions of the development area  8  of the test strip  13 , where the dimensions of the window(s) are configured to maximise the proportion of test result lines  5  framed relative to the proportion of test background framed. The cassette assembly  15  also includes a reset activation recess  27 . Again, it is noted that the plurality of windows of the cassette window structure  24  in  FIG. 3A  serves to mask the test strip  13 .  FIG. 3B  illustrates an alternate arrangement wherein the viewing area  26  includes a cassette window structure  24  which is one large window and the portions of the development area  8  are framed with masking features  25  integrated on the test strip  13 , such that the masking is configured to maximise the proportion of result lines relative to the proportion of test background. 
     For a singleplex assay with one test line  5  and one control line  7 , at least three windows are required, one window for the test line, one window for the control line  7  and at least one window for the strip background. Preferably, four windows with two windows for strip background measurements improve test sensitivity. In this preferred configuration, the first and third windows are each for a strip background calibration measurement the second window is for the test line and the fourth window is for the control line  7 . Optionally, the background calibration measurement can be reduced to a single strip background calibration area in the first window. For multiplex assays with two or more test lines, the second and third window each frame one test line, with further additional windows provided for each additional test line over two test lines. For a cassette  15  with five windows  24  as depicted in  FIG. 3A , the maximum number of test lines  5  would be three, where there has to be at least one strip background region  6  and there could be three test lines  5  and one control line  7 . 
       FIG. 4  illustrates how the cassette is configured such that a test result line  5  of the test strip  13  is positioned within a cassette window structure  24 . The combined tolerance  29  of the cassette recess that nests the test strip and test strip  13  itself (including tolerance of the result line width, tolerance of position of the result line on the test strip, tolerance of position in the cassette, tolerance of window size and safety factor) are sufficient to ensure that the full width  28  (parallel to the direction of flow  3 ) of each result line is positioned within the width of the cassette window  30 . The height of the window  31  is configured to the test strip width  32 , excluding the lateral edges  33  where non-uniform non-specific binding is expected to occur. 
     In the embodiment of  FIG. 4 , the dimensions of the cassette windows  24  are configured such that the width of the window is equal to the width of the test or control line plus the tolerances of manufacture of one or a combination of the test strip  13  and cassette  15 . In this respect, the tolerances of manufacture may include the sum of the tolerance of the test line width  28 , the tolerance of test line positioning on the test strip  13 , the tolerance of test strip nesting in the cassette recess, and the tolerance of the window width  30 . For example, a 1.5 mm wide test line would be framed by a window at least 1.5 mm wide, wherein the width of the window is 1.5 mm plus the tolerances of manufacture. In this example, in combination with controlled manufacturing processes, the window width may be around 2.5 mm to allow for the realistically expected manufacturing tolerances. In use, the cassette is removably inserted in an electronic reader, which comprises an illumination source for illuminating the test result lines  5  and test background regions  6  on a lateral flow test strip  13 , and measurement sensors  37  for detecting light reflected or emitted from the test lines  5 . 
     The cassette  15  is configured such that each result line of the test strip  13  is positioned or aligned for inspection within a separate cassette window  24 . The tolerance of the cassette recess which nests the test strip and test strip itself should be sufficient to ensure that the full width (parallel to the direction of flow  3 ) of each result line is positioned within a cassette window  24 . Because these tolerances are known and tightly controlled the windows can be sized as small as possible while ensuring the full width of each of the result lines is positioned within a separate window. This ensures that the signal measured from the result line is maximised and signal from the test background is minimised. The cassette and test strip tolerances should be accommodated to ensure that the entirety of the line remains in the window and visible to the entirety of the LED and photodiode active surface areas when the cassette and strip tolerances are all at their worst-case extremity. If the cassette window is misaligned with respect to the carrier window  40  along the long axis of the cassette, it has little impact on the signal since there is no additional obscuration of the line due to alignment error (as the carrier window is designed to be sufficiently larger than the cassette window that it allows for this alignment error and the whole of the cassette window remains “visible”) The alignment position error may contribute a cosine error due to small angular changes, as does the line position within the cassette window. 
     The height of the cassette windows  31  (perpendicular to the flow) are smaller than the full width of the test strip to reduce the interference from edge artefacts. The edges of a lateral flow test strip  13  tend to have non-uniform and or non-specific binding of analytes and/or antibodies producing resultant artefacts, which adds additional noise to the overall signal derived from test and control lines. 
     The cassette window height  31  is sized such that there is a balance between maximising the amount of test strip exposed for measurement and excluding the interference from the above noted edge artefacts. Preferably, the cassette window height is such that the height of window is less than or equal to the test strip width (perpendicular to the flow) minus manufacturing tolerances. The manufacturing tolerances for window height includes, the test strip width, the tolerance of test strip nesting in the cassette recess, and the tolerance of the cassette window. 
     In a preferred embodiment, around 0.35-0.40 mm of the test strip edging is covered on each side of the test strip by the cassette housing on each side of the cassette window, wherein the cassette window is centred in relation to the test strip when nested in the recess of the cassette. For example, the cassette window height is around 3.25 mm +/−0.05 mm high for a 4 mm wide test strip. For a 6 mm wide test strip the cassette window height is around 5.25 mm +/−0.05 mm, and for a 2 mm wide test strip it would be around 1.25 mm +/−0.05 mm. 
       FIG. 5  illustrates how the cassette window structure  24  is intended to frame the result line  5  of the test strip.  FIG. 5A  illustrates a result line ideally centred in the cassette window  24 ,  FIG. 5B  illustrates a result line  5  where the full width is positioned within the cassette window  24 , and  FIG. 5C  illustrates a result line  5  that is overlapping the cassette window  24  and partially obscured by the cassette housing. The proportion of result line  5  and test background region  6  positioned within the window  24  is equal in  FIG. 5A  and  FIG. 5B  but not in  FIG. 5C . 
       FIG. 6  illustrates a side sectional view of the PCB  16  mounted on the carrier  17 .  FIG. 7A  illustrates a sectional view of the PCB  16  mounted on the carrier  17  as viewed from the bottom,  FIG. 7B  is a detail view of the carrier windows  40  showing the light and sensor separator feature  43 , parallel to the direction of flow  3  on the test strip, which prevents the light from the illumination LED  38  from reaching the measurement sensor  37  directly. This arrangement allows for the measurement of the reflected or emitted light from the test strip  13 . The adjacent sensor separators  44  perpendicular to the direction of flow  3  frames the window around the sensor and prevents light reflected or emitted from adjacent windows from reaching the measurement sensors. In one embodiment as shown in  FIG. 7B , the active areas of measurement sensor  37  and LED  38  pairs are offset so as to fit a plurality of sensors  37  (in this example six sensors) within the standard lateral flow strip dimensions to maximise the number of areas that can be separately measured on a lateral flow test strip. In another embodiment, the centres of the active areas of the light source  38  and sensor  37  pairs are uniformly aligned and each pair is centred within the aligned carrier and cassette windows. 
       FIG. 8A  illustrates a view of the cassette  15  inserted into the opening  18  in the carrier  17 ,  FIG. 8B  is a sectional view of the cassette with test strip inserted into the reader carrier. 
     In a preferred embodiment the cassette is removably retained within the reader by a snap fit mechanism. The elements of the snap fit mechanism may reside upon or within the cassette and/or the reader and their assistance with alignment of the cassette within the reader contributes to consistent and correct measurements. 
     As would be appreciated by the person skilled in the art, any suitable snap-fit mechanism may be employed and may comprise annular, cantilever or torsional snap-fit arrangements. Preferably a cantilever snap-fit mechanism is employed. The snap fit mechanism in a particularly preferred embodiment comprises a snap fit retaining mechanism and lateral biasing means to retain and align the cassette within the reader. The lateral biasing means may comprise spring elements which may be separate or integral spring features such as leaf or coil springs, or alternatively the inherent structural compliance of the reader and or cassette components may be employed, particularly as these components are constructed of polymeric materials. In a preferred embodiment, the snap fit mechanism comprises lateral biasing means on the carrier and snap fingers on the cassette (or alternatively in a mechanical inversion, lateral biasing means on the cassette and snap fingers in the reader) work together to ensure that the cassette is ultimately positioned consistently and correctly in the reader. 
     Preferably, the lateral biasing means and the snap fingers work together such that the lateral biasing means push the cassette out towards the opening of the reader and the snap fingers act as a retaining mechanism to retain the cassette within the reader. Together the elements of the snap fit mechanism hold the cassette in a reading position within the reader. When the cassette is nested optimally in the reader, the cassette windows align with the carrier windows that frame the illumination LEDs and measurement sensors. Misalignment of the cassette windows and carrier windows would impact on the signal measured as misaligned windows would obscure the result lines and ultimately reduce measurement performance. Preferably, the snap fit mechanism aligns the cassette and reader carrier windows such that the position of each test result line  5  is centred in the aligned respective windows. This alignment of the cassette within the reader contributes to consistent and correct measurements. 
     Other retaining mechanisms such as retention clips on the reader which engage features on the cassette can be used to align and retain the cassette within the reader. Additional retaining features such as alignment pins and associated holes or bosses can also be used to retain the cassette within the reader and secure alignment within the reader. 
     In a particularly preferred embodiment, the reader also comprises vertical biasing means for positioning the cassette vertically towards the measurement area. Preferably, the vertical biasing means comprise one or more leaf springs that urge the cassette towards the electronic components or the reader used for measuring. This contributes to maintaining a consistent distance between the assay test strip and the electronic components used for measuring, and hence consistent measurement. Due to light scattering, not all of the light emitted by the illumination LED reaches the test line, and not all the light reflected or emitted by the test line is detected by the measurement sensor. A consistent distance between the assay test strip and the measurement region ensures that the same proportion of light is detected by the measurement sensors. 
     Preferably, the vertical biasing means comprises two leaf springs that urge the cassette towards the electronic components used for measuring, wherein the first leaf spring urges the cassette towards the electronic components for measuring, such that the cassette windows and carrier windows are in contact and wherein the second leaf spring maintains the cassette parallel with the PCB. 
     Preferably the cassette  15  is removably retained within the reader by a snap fit mechanism comprising snap fingers  23  and a biasing means  35 . The snap fingers on the cassette  23  and the biasing means  35  on the reader carrier  17  ensure that the cassette windows are aligned correctly in relation to the measurement area  39 . The measurement area  39  comprises carrier windows  40 , which are divided by a barrier  43  to act as a light guide for the measuring system comprising illumination LEDs  38  for illuminating the result lines  5  and  7 , and test background regions  6  of the test strip and electronic measurement sensors  37  for sensing light reflected or emitted from the test strip. Preferably one LED is paired with one sensor to illuminate and measure signal at one portion of the development area  8 , such as the test line  5 , control line  7  or strip background region  6 . Additional LED-sensor pairs are used to measure another portion of the development area  8  of the test strip. Preferably the windows  24  in the viewing area  26  of the cassette are centred with the windows  40  in the measurement area  39  of the carrier. 
     In a particularly preferred embodiment the biasing means are leaf springs  34  that urge the cassette  15  towards the electronic components used for measuring.  FIG. 6  is a sectional view illustration of a particularly preferred embodiment of a carrier  17  of an electronic reader according to the present invention having two leaf springs  34  that help align the cassette vertically to the reader. In this arrangement, one leaf spring pushes the cassette so that the carrier  17  and cassette  15  are in contact and the second leaf spring maintains the cassette parallel to the PCB  16 . The leaf springs  34  assist in maintaining a consistent distance between the assay test strip in the inserted cassette and the electronic components of the reader used for measuring, and hence reduces measurement variables by maintaining a consistent measurement depth. The distance between the test strip and measurement components are optimised in order to position the overlap of illumination area and measurable area on the area framed for measurement. Depicted in  FIG. 14A  and  FIG. 14B  is a detailed view of the cross section of a cassette  15  in the carrier  17  showing illumination paths associated with an illumination LED  38  and measurement sensor  37  pair for a portion of the development area  8  of the test strip  13 . With respect to the test strip to LED/sensor distance, the inverse-square law operates. However, the present inventors have found that because of the limited “field of view” of the LED  38  and sensor  37  and the associated geometry, there is a point beyond which further reduction in separation distance actually reduces signal rather than increasing signal. The present inventors found that the area framed for measurement  46  was optimal at a test strip to PCB distance of between about 2 mm and 5 mm. Preferably, strip to PCB distance of about 3 mm to 4.5 mm. More preferably, strip to PCB distance of about 4.1 to 4.5 mm. 
     The present inventors found that by separating of the light guide function between the carrier  17  and cassette  15  that they could optimise the light guide function. In this arrangement, the carrier windows  40  (including the separator  43 ) can extend towards the PCB  16  surface to surround and separate the illumination LEDs  38  from the measurement sensors  37 , whilst allowing for other masking features to be placed in close proximity to the lateral flow strip  13  as a plurality of cassette windows  24 . Allowing the inventors to minimise the distance between the test strip  13  and the cassette window  24 . For functionality reasons, the distance between the top surface of the test strip  13  and the bottom surface of the cassette windows includes an air “gap” such that the cassette windows  24  do not directly contact the test strip  13  surface as such contact may interfere with flow of sample solution along the test strip  13 . Since this distance represents a “gap” it leads to the creation of shadows which act to restrict or provide a limitation to the illuminated portion of the test strip  13 . These shadows are dependent on both the distance between the strip and the cassette window and also distance of the strip to the LED/sensor pair. The shadows are caused by the interaction of light paths, the carrier window  40 , the cassette window  24  and their relative locations, which is evident with reference to  FIG. 14B . 
     The cassette is configured such that each result line of the test strip is positioned within a separate cassette window, and at least one strip background region  6  is framed by a separate cassette window  24 . The tolerance of the cassette window  24  and test strip in terms of manufacturing and assembly are sufficient to ensure that the full width (parallel to the flow) of each result line is positioned within a window  24 . Because these tolerances are known and tightly controlled the windows  24  can be sized as small as possible while ensuring the full width of the each of the result lines is positioned within a separate window  24 . This ensures that the signal measured from the line is maximised and signal from the test background is minimised as per  FIG. 5 . 
     Cassettes of the prior art are typically white, or a light colour such as pink, light blue or light green to provide visual contrast to the darker test lines. However, counter intuitively to this, it has been recognised that the use of minimally reflective cassette colour such as black improves the reader contrast. A minimally reflective cassette means that less light is reflected off the cassette and into the measurement sensors. The term ‘minimally reflective’ is intended to include any combination of surface and colour that is non-reflective or absorbs wavelength of the illumination source in the electronic reader. This helps reduce the reflected light from the ambient environment and prevents the reflected light from straying into neighbouring measurement areas. Furthermore, it contributes to maximising detection of reflection from the test result line  5  and reducing background region signal noise. 
       FIG. 9  is a plot of measured attenuation against line intensity comparing the performance of black and white cassettes with a reader of a preferred embodiment of the present invention. Black and white cassettes were tested with three lateral flow test strips with varying line intensities. Each test strip was placed in 5 white cassettes and 5 black cassettes and measured in the reader of the present invention. On average the test strip in the black cassettes had 75% higher attenuation than the same test strips in the white cassettes. 
     The result of the test depicted in particular was performed with a colorimetric reader and illumination LEDs with a peak wavelength of 570 nm. A black cassette was used to minimise reflections of all wavelengths, but alternative cassette colours could be used as long as the reflectance of the illumination LEDs is minimised and the absorbance maximised. 
     The same principle can be applied for a fluorescent reader where the cassette material chosen is known to be minimally fluorescent under the illumination LEDs. 
     The use of minimally reflective or emissive material in the cassette results in less light reflected off or emitted by the cassette and into the measurement sensors. This helps reduce the effect of light from the ambient environment and prevents the light from the illumination LEDs from straying into neighbouring measurement areas and back into the sensors. Rather it helps prevent light straying from the LED to an adjacent measurement area of the test strip and back to the measurement sensor. Adjacent channel sensors would not normally be active and so should not detect stray light. Furthermore, it contributes to maximising detection of reflection from the test line and reducing background signal noise. 
     The inventor recognises that the relative intensity of an LED source may be dependent on its forward current. In preferred embodiments, a voltage source arrangement is used to power the illumination LEDs. Because of this voltage source arrangement, the forward current of the LED is affected by both the temperature of the semiconductor die, the diode forward voltage, and the supply voltage, which is typically supplied by a battery. While a more complex current source arrangement would not exhibit these issues, a voltage source arrangement is preferred to minimise complexity and maintain a low-cost design. 
     The LED die temperature and forward voltage will be dependent on the ambient temperature, frequency of use and current level, such as from the battery supply. Typically, the compensation is calculated and applied by measuring the forward current prior to the start of the test, and then again after. The difference in the forward currents as a ratio may be used by way of appropriate calculations or algorithms in software routines to compensate for any die temperature and battery voltage effects which influence the forward current between the start of the test and when the sample has developed. Applying compensation ensures that the assay measurement results are consistent across the life of the electronic reader. An example of this process is as follows;
         (i) Cassette is inserted by the user.   (ii) Forward current of the illumination LEDs are measured and recorded.   (iii) The blank test strip is measured and recorded.   (iv) The user is signalled to apply the sample.   (v) The user applies sample.   (vi) The sample is detected, and the reader waits a predetermined amount of time sufficient to allow for development to occur.   (vii) After the test is complete, the forward current of the illumination LEDs are measured and recorded.   (viii) The developed test strip is measured and the result recorded.   (ix) Using the recorded current and result measurements, a compensated result is calculated.   (x) A compensated result is displayed to the user.       

       FIG. 10  is a sectional view illustrating operation of a reset switch as a cassette is being inserted into, and removed from, a reader of an embodiment of the present invention showing arrangements in which the reset switch is open ( FIG. 10A ), closed ( FIG. 10C ) and re-opened as the cassette is removed from the reader ( FIG. 10B ).  FIG. 10  illustrates the operation of a reset switch  36  as a cassette  15  is inserted into or removed from a reader of the present invention.  FIG. 10A  and  FIG. 10C  show the conditions when the reset switch is open while  FIG. 10B  shows the reset switch  36  is in a closed position. When the cassette  15  is inserted into or removed from the opening in the reader, a normally-open switch is activated which allows the reader to wake-up. This allows the reader to reside in a low power mode while not being used, decreasing the power consumption requirement. This increases the shelf life of the reader. It also has the advantage, compared with the simpler alternative of powering/de-powering the reader using a cassette activated switch, that the reader remains powered after cassette removal—enabling the reader to continue to perform functions such as extended display, communications etc. after cassette removal. It also permits a lower capacity and corresponding less expensive battery to be used. 
       FIG. 11  is a schematic circuit diagram illustrating a basic electronic arrangement according to preferred embodiments of the present invention for the LEDs used in the reader wherein 3 pins controlling 6 LEDs. The remaining 6 LEDs are arranged in a slightly different arrangement, using IO pins 1-3 as well as adding two new pins IO 4  and IO 5 .  FIG. 11  illustrates the electronic architecture of a preferred embodiment of the present invention, which allows the use of a greater number of measurement positions and user feedback LEDs than are typically possible with low cost microcontrollers of the prior art. 
     Typically, in prior art systems, each IO pin controls a single LED. The present invention instead uses a combination of charlieplexing and multiplexing to control multiple LEDs (e.g. twelve, 6 user feedback LEDs and 6 illumination LEDs) from five digital IO pins. Charlieplexing is a multiplexing technique which relies on a combination of the behaviour of LEDs and the tri-state nature of modern microcontroller pins. The IO pins can be High voltage (sourcing current) or Low voltage (sinking current), or High Impedance. A combination of pins being turned between high voltage, low voltage and high impedance can be used to selectively turn on the required LEDs. The critical aspect is that switching occurs on both the high voltage and the low voltage side of a load (normally a load is only switched on either high or low side and not both) and that either side of a load may be positive or negative polarity. 
       FIG. 12  is a table that shows how charlieplexing and multiplexing can control a very large number of loads as the number of available pins increases. Charlieplexing allows polarity sensitive loads (such as LEDs) to be controlled such that the number of controlled loads is equal to n*(n−1), where n is the number of I/O pins. In comparison, a typical multiplexing arrangement allows for (n/2) 2  controlled loads to be controlled by n I/O pins. 
     In a preferred embodiment of the present invention, charlieplexing is used to control the six user feedback LEDs while the remaining 6 LEDs are in a multiplexing arrangement, utilising IO pins 1-3 as well as adding two new pins IO 4  and IO 5 . This is done to accommodate the current measurement and compensation feature as described herein. 
     This configuration has a disadvantage in that only a single LED can be powered on at once. The restriction is consistent with the desire to have predictable and low current draw from the battery. For this reason, it is preferable to avoid having multiple LEDs on simultaneously. 
     Furthermore, the design and architecture of this device is such that only a single LED is ever needed to be turned on at any one time. The illumination LEDs are turned on one at a time and the user feedback LEDs are only on when illumination measurements are not occurring. The operation of Measurement and User Feedback LEDs may be interlaced in such a way that multiple User Feedback LEDs may appear to a user to be on simultaneously or such that User Feedback LEDs may appear to be on during measurements but only one LED is ever on. For example, switching two LEDs rapidly on/off so that they both appear on but only one is on at any one time is preferable to having both LEDs on. This way, multiple LEDs may appear to be on when in fact only a single LED is ever switched on at one time. 
     Multiple LEDs allows the inclusion of other functionality such as a cassette presence/absence detection feature. This feature can be implemented using the LEDs and sensors already provided for user feedback and test illumination. This way the user experience is improved by reducing the number of required interactions prior to performing a test is implemented in software without any additional components. 
       FIG. 13  illustrates one preferred embodiment of the cassette presence/absence detection feature where the user feedback LED  21  closest to the point at which the cassette  15  is inserted in the opening is turned on and measured by the measurement sensor  37  that is also intended for measuring the test strip. The reader can detect when a cassette is inserted in the reader ( FIG. 13A ) because the light from the user feedback LED is blocked and does not reach the measurement sensor. The reader can also detect the condition when there is no cassette inserted ( FIG. 13B ), because the light from the user feedback LED reaches the sensor. A threshold in software can be used to determine the presence/absence of a cassette where a low measured signal means a cassette is present and a high measured signal means a cassette is not present. A combination of the reader reset switch and the cassette detection features can be used in software determine what the user intends to do. For example, if the reset switch is toggled and a cassette is detected, it is likely that the user has inserted a cassette and intends to start a test. The alternative scenario is if the reset switch is toggled and there is no cassette detected, then it is likely that the user has just removed a cassette, the powered-on reader can now continue to perform functions such as displaying the result of the previously completed test or maintaining communication with an external device. 
       FIG. 14A  provides a cross sectional view of a cassette assembly  15  (cassette top  12 , cassette bottom  14 , and strip  13 ) inside the reader carrier  17 , cross sectioned through an aligned cassette window  24  and carrier window  40 , illustrating the separated light guide functionality. The light guide section of the carrier has been synonymously referred to above and herein as the “carrier windows” and the light guide section of the cassette has been synonymously referred to above and herein as the “cassette windows”. The light guide is a functional mask in that restricts the illumination and/or measurable area of the positioned test strip and reduces the refraction and reflection of light to increase the signal to noise ratio. Preferably, the light guide components act mainly as an absorber rather than a refractor or reflector of light. Therefore, in preferred embodiments, light which is reflected from the mask itself is also masked by the differing 3-dimensional structure and positions of the cassette windows  24  and carrier windows  40 . The paths of light to or from the illumination LED  38  and to the measurement sensor  37  are shown to be blocked by the separator  43  of carrier windows  40  and cassette top  12  and cassette windows  24 . It should be noted that  FIG. 14A  is essentially a simplified diagram because in reality the light would be bouncing off multiple surfaces. It is also worth noting that the separator  43  as shown is actually part of the carrier window  40  (see  FIG. 16  D).  FIG. 14B  is a detailed view showing how the paths of light to and from the illumination LED  38  and to the measurement sensor  37  fall on the test strip  13 , leading to three distinct regions; where the light is incident on the strip  13  but not measured, measurement shadow  45 , where the light reaches the strip  13  and is measurable by the sensor  46 , and where the sensor may be able to measure but no light reaches, illumination shadow  47 . Again, the representation of  FIG. 14B  is a simplified diagram that implies that there is no light outside of the light paths and 100% of the light is contained within the light path where as in reality the light paths and illumination profile is more complex.  FIG. 14C  is a simplified top view of the test strip  13  which illustrates how the light guide features ensure that the area framed for measurement  46  in the strip  13  is illuminated and measurable through the cassette window  24 , excluding the regions of non-uniform non-specific binding  33 . 
     The illustration of  FIG. 15A  and  FIG. 15B  depicts a single use version of the lateral flow assay electronic reader of a preferred embodiment of the present invention comprising a PCB  16  with a battery  19 , on top of a light guide  50  above a strip  13 , encased in a two part housing (top  48  and bottom  49 ). The PCB  16  holds user feedback LEDs that are visible through holes or apertures  21  in the housing, as shown best in  FIG. 15B . A separate light guide  50  is included, which is part of the carrier in the multiuse reader of the other embodiments described herein. 
       FIG. 16A  and  FIG. 16B  are section views showing an overlay of the LED  38  and sensor  37  locations on top of the carrier  17  and cassette assembly  15 . In  FIG. 16B  the test line  5  and control line  7  are visible.  FIG. 16C  is a detailed view of the cassette inside the carrier with a clearer view of the individual carrier windows  40  separated by the illumination and sensor separator  43  and adjacent sensor separators  41 . The test line  5  and control line  7  are framed by the cassette windows  26  which in turn are framed by the carrier windows  40 .  FIG. 16D  is a detailed view of the carrier windows  40  without the cassette  15  inserted in the carrier  17 . 
       FIG. 17A  and  FIG. 17B  are 3D section views illustrating a cassette  15  fully inserted into a carrier  17  and the reset switch on the PCB  16 . It is an alternate view of  FIG. 10A . 
       FIG. 18A  and  FIG. 18B  are side section views of a cassette  15  inserted in a carrier  17  showing the alignment of the cassette windows  24  and the carrier windows  40 . 
       FIGS. 19A, 19B, 19C, 19D, 20A, 20B and 21  show an electronic multiuse reader. The multiuse reader  51  has a reader top  53  and a reader bottom  54  defining a cavity  63  for receiving a cassette  71  with an associated test strip  13 . The cavity  63  is further defined by a reader door  56 . The reader door  56  may contain an angled lip  68  which interfaces with a lip interface  67  of the carrier  17 . 
     The reader top  53  includes a user interface  55  powered by a battery  19  and controlled by a PCBA  78  mounted to a carrier  17 . The carrier  17  comprises a top and side walls. Optionally the carrier further comprises a bottom. The carrier  17  contains carrier windows which are configured to acts as a light guide  88  (see  FIGS. 27A-27B ) alone or in combination with the cassette windows  24  when a cassette  71  is inserted into the reader  51 . The user interface  55  provides a reading of a detected reagent on the test strip  13 . At least one end post  64  extends from the carrier  17  into the cavity  63 . Locating bosses  62  extend from an under face of the carrier  17  within the reader top  53 . The locating bosses  62  preferably extend the full height of the cassette  71 . 
     In an alternate embodiment, the locating bosses  62  can extend into the cavity  63  from the reader bottom  54  or a bottom internal face of the carrier  17 . The reader top  53  is preferably rounded. 
     The reader bottom  54  has an outside reader dock  57  extending to a door receiving section  69  for receiving the reader door  56 , and an alignment section  70  with at least one alignment recess  61  and a spring clip  60  or leaf spring. The spring clips  60  are preferably rounded to reduce friction between the bottom of the cassette  71  and the spring clips  60 . The door receiving section  69  and the alignment section  70  are within the cavity  63 . The reader docket  57  is preferably of a length to support the cassette  71  when it is inserted into the reader  51 . The reader bottom  54  is flat for level seating on a surface. 
     One of the advantages of using a flat reader bottom  54  and a rounded reader top  53  is to encourage placement of the reader and an associated cassette  71  on a flat, level surface, allowing the assay on the test strip  13  of the cassette  71  to run horizontally and prevent temperature changes during measurement by the reader  51 . 
     The reader door  56  has a hinge mechanism in which the door is rotatably attached to the reader  51  by a door pin  58  on either side of the reader door  56  which is received by a reader door socket  59 . In an alternate embodiment, a torsion spring can be added to the hinge mechanism. 
     The reader door  56  has a closed position and an open position. In the open position, the reader door  56  rotates such that the reader door  56  is received by the door receiving section  69  of the reader bottom  54 , and an external face of the reader door  56  is adjacent to an inserted cassette  71  for example as shown in  FIG. 21 . In the open position, the door acts to align the cassette  71  within the reader  51 , for example by applying a vertical biasing force to the cassette, similar to the vertical biasing springs. 
     When the reader door is in the closed position, the reader door  56  safeguards internal electronics such as the battery  19  and the PCBA  78 , including illumination sources  38  and measurement sensors  37  from dust and other contaminants as well deterring cleaning within the cavity  63  of the reader  51 . The reader door  56  is preferably biased towards the closed position by one or more springs  65  located within the reader bottom  54 , allowing the door to self-close when the cassette  71  is not present within the reader  51 . The one or more springs  65  can interface with one or more recesses (not shown) on the internal back face of the reader door  56 . The springs  65  can be made of various materials, such as plastics, metal or other materials which provide resilience and spring force to maintain the reader door  56  in the closed position and allow insertion of a cassette  71  to push the reader door  56  to an open position. The springs can be leaf springs, torsion springs or other springs. 
     The angle of the reader door  56  within the reader  51  is such that the reader door  56  allow insertion of a cassette  71  to push the reader door  56  to an open position without causing misalignment of the cassette  71  within the cavity of the reader  51 . In addition, as the cassette  71  pushes the reader door  56  into the open position, the reader door  56  can be stored within the reader bottom  54  and the cassette  71  slides over the reader door  56  and passes between the lip interface  67  and the reader bottom  54 . The lip interface  67  may be part of or integral to the reader top  53  or the carrier  17 . The angle of the reader door  56  is such that in the closed position, any gap between the lip interface  67  and the reader door  56  is minimized. The angle of the reader door  56  within the reader  51  is also such that a seal is not necessary. The angle of the reader door  56  is complementary to the lip interface  67  of the carrier  17  to allow mating of the lip  68  of the reader door  56  with the lip interface  67  to prevent liquid, dust, or light to ingress into the reader  51 . 
     While not shown in this embodiment, side rails may be added to the cassette  71  and the reader  51  to increase alignment of two. 
       FIG. 22A-22B  show sectional views of the cassette  71  inserted into the multiuse reader  51 . Soldered to the PCBA  78  is a cassette detection switch  73  which protrudes into the cavity  63  in which the cassette  71  is inserted. 
     To enable the reader  51  to determine whether or not a cassette  71  is present, a top face of a cassette top  77  has two parallel channels  76  each with a bump  75  and a raised surface  74 . In an alternate embodiment, a single channel  76  with a bump  75  and raised surface  74  may be used. As the cassette  71  enters the multiuse reader  51 , the bump  75  and the raised surface  74  alternately activate, release and activate the cassette detection switch  73  on insertion and release. Upon removal of the cassette  71 , the cassette detection switch  73  is activated and released. The activation of the cassette detection switch  73  wakes up the multiuse reader  51  (from a low power state) and also enables the detection of a cassette  71  in the reader  51 , which then triggers the workflow. Since the multiuse reader  51  can be activated upon entry of the cassette  71 , the reader  51  can be maintained in a low-power state to conserve battery life when not in use. 
     An AC coupling circuit interfaces this switch to the microcontroller (MCU) to prevent the MCU from being stuck in its reset (high power) state in the case of partial cassette insertion. 
       FIG. 23A-23B  show close ups of the PCBA  78 . The electronics of the PCBA  78  have been designed with low-cost assembly in mind. The PCBA  78  is a two-layer circuit-board with single cycle reflow soldering only. Given that the battery  19  connection is on the opposite side of the board, a custom positive battery terminal  79  is designed to be inserted through the board  78  and soldered on the same side of the board  78  as the rest of the components. By soldering on a single side only, the risk of heat damage due to multiple soldering cycles to sensitive optics components is avoided. 
     On the bottom side of the PCBA  78  are optics components  80 , such as LED  38  and measurement sensors  37 , which are used to read the test strip  13 . The battery  19  and a liquid crystal display (LCD) (user interface)  55  are located on the top side of the PCBA  78 . 
     It is preferred that the method used to interface the battery  19  to the PCBA does not result in an additional solder cycle. Furthermore, the battery terminal preferably fits through the PCBA  78 . The compression force and surface area of the terminal  79  on the battery  19  must ensure reliable connection. 
       FIG. 24A and 24B  refer to circuit diagrams illustrating a simplified architecture to drive a multiplexed LCD arrangement. The arrangement allows for multiplexed LCD drive implementation without a dedicated hardware driver. This arrangement allows simplified architecture to drive a multiplexed LCD directly from a microcontroller without a hardware driver peripheral, using a software driver and external resistor network (R8 to R15). 
     To display quantitative results, an LCD (see  55 ) is incorporated into the reader  51 . This LCD has a multiplexing ratio of 4. Instead of adding a dedicated hardware driver, the multiplexed LCD segments are driven directly by the microcontroller (MCU) using a software driver. The MCU is already used for other functions in the reader, so no additional integrated circuit is required. By using this arrangement, the number of integrated circuits in the system is reduced, as well the surface area of board space required, allowing a smaller board design and low cost architecture to be used. 
     To turn an LCD segment On, an AC voltage with a specific root-mean-square threshold voltage must be applied to the segment&#39;s electrode. This voltage level for each segment is generated by the MCU in the form of periodic, square waveforms that are either in-phase (segment off) or out-of-phase (segment on). An external resistor ladder is required to set biasing voltage levels. 
       FIGS. 25-27B  show alignment and positioning mechanisms for the cassette within the multiuse reader. 
     To make sure the cassette  71  does not move when the multiuse reader  51  is handled by a user, two retention clips  72  which are attached to or formed as part of the carrier  17 , releasably engages with ramp  106  at an end portion of the cassette  71 , preferably the cassette top. The retention clips  72  engage with the cassette  71  adjacent the channels  76 . At the end portion of the cassette  71  are ramps  89  built into the cassette face  77  for gradual interference with the retention clips  72  followed by sudden engagement of the retention clips  72  when the cassette  71  is fully inserted in the reader  51 . For release, the retention clips  72  each have a rounding the face  105  so gradual extraction from the cassette  71  is possible. 
     The two retention clips  72  each preferably engage with a thin rib  81  of the cassette top  77  surface. The retention clips  72  may also provide haptic feedback to the user when the cassette  71  is fully inserted into the reader  51  as retention clips  72  snap into place onto the cassette  71 . 
     By having the retention clips  72  be a part of or attached to the light guide  88 , the retention clips  72  and the positioning and alignment features as described further below present on the same part reduces the tolerance stack. This reduction in tolerance stack, reduces the allowances for tolerances required during manufacture. 
     The retention clips  72  can also be used pull the cassette  71  into the multiuse reader  51  and maintain an alignment pin  82  of the cassette up against the hard stop  92  of the alignment hole  91  in the reader  51 . 
     An alignment pin  82  is integrally formed with a strip platform  90  which receives the test strip  13  within the cassette  71 . The alignment pin  82  extends through the cassette top  77  and can be aligned with a locating or alignment hole  91  of the light guide  88  as well as an alignment boss  87  of the PCBA  79  of the multiuse reader  51 . The alignment hole  91  of the light guide  88  has a hard stop  92  which engages with the alignment pin  82  once received within the alignment boss  87  and the alignment hole  91 . The alignment hole  91  of the light guide  88  additionally assists with alignment of the electronic components of the reader to the light guide  88  and the test strip  13 . 
     The alignment pin  82  is offset onto one side of the cassette  71  housing so that the alignment pin  82  can extend from the strip platform  90 , through the top of the cassette housing without interference with the test strip  13 . 
     As the cassette  71  is inserted in the reader  51 , the interaction of the alignment pin  82  and the hard stop  92  of the alignment hole  91  stops the cassette  71  at the correct position for the alignment of the windows  24  of the cassette  71  the carrier  17 , the PCBA and electronics/optics (not shown), and the test strip  13 . The U-shaped recess  66  of the lip interface  67  (see  FIG. 20B ) allows the alignment pin  82  to slide into the reader  51  until the hard stop  92  of the alignment hole  91 . 
     In an alternate embodiment, more than one alignment pin  82  can be used to stop horizontal rotation (to left and right along the horizontal plane) and to reduce tolerance of positioning of the components. In one example, two location pins are provided with one to either side of the windows  24  on the cassette  71  similar to the location pins and posts present in the single use reader of  FIG. 15A and 16C . 
     In another alternate embodiment, the alignment pin  82  may extend from the reader and mate with a recess in the cassette. In this embodiment a rail that the alignment pin could slide in would be present on the cassette. 
     With the alignment pin  82  holding the cassette  71  in the right position within the alignment hole  91  and alignment boss  87 , the cassette  71  would still be able to shift up and down. To ensure vertical alignment, the bottom of the reader  51  has in-built spring features such as spring clips  60  to always push the cassette  71  up onto the bottom surface of the light guide  88 . In addition, the thin ribs  81  of the cassette top  77  set the height between the top surface of the cassette  71  and the bottom surface of the light guide  88 . This allows the top face of the cassette top  77  with the windows  24 , which is slightly recessed, so that the split light guide  88  between the cassette  71  and carrier  17  of the reader  51  do not rub against each other. There is no direct contact between the windows  24  on the cassette  71  and the carrier windows  40 . The top face of the cassette top  77  forms a contact with the carrier  17  and assists to block light ingress. This shallow recess is shown, for example in  FIG. 14A  between carrier  17  and a top surface of cassette top  12 . The lack of direct contact of the light guide  88  with windows  24  is important for the multiuse reader  51 , as direct contact of the windows  24  of the light guide  88  would result in friction and wearing of the light guides  88  over time as the cassette  71  is insert and removed from the reader  51 . 
     The alignment pin  82  and alignment boss  87  work in conjunction with the locating bosses  62  to reduce the movement of the cassette  71  side to side along the horizontal plane. 
     The various alignment features described above aid in providing consistent alignment and positioning of the removable cassettes within the reader. Having correct alignment and position of cassettes within the reader reduces errors in reading results, improves variability test to test (reduces reader CV) and improves reader sensitivity. 
       FIG. 28A and 28B  show the blood collection unit blocker of the multiuse reader in conjunction with the cassette. 
     The multiuse reader  51  also preferably has an integral blood collection unit (BCU) blocker  90 . The blocker  90  physically prevents rotation of a blood collection unit arm  91  of the cassette  71  from being rotated around an axis  92  after the cassette  71  has been inserted into the multiuse reader  51 . The BCU blocker  90  may also assist in blocking light ingress to the reader  51 . 
     In one embodiment, the cassette may be the Pascal RDT Platform from AtomoRapid™ Integrated Rapid Diagnostic Test Platforms of Atomo Diagnostics. Therefore, in order for the multiuse reader  51  to be used, the user has to deposit a sample onto the test strip  13  via the blood collection unit  83  of the cassette  71  prior to insertion of the cassette  71  into the reader  51 . 
     The multiuse reader  51 , especially the area close to the blood collection tube  84  of cassette  71  is preferably of a color that visually contrasts highly with blood (e.g. white) and smooth so that a user can do a quick visual check to determine whether there was any blood contamination. 
       FIG. 29A-29D  shows views of a cassette with a slide-on multiuse reader. 
     Before doing any readings, a sample is collected and deposited, for example by the BCU  83  into the sample port  85  of the cassette  71  and onto the test strip  13  by rotating the BCU  83 . This cannot be done after the reader  92  has been put into place. 
     The slide-on multiuse reader  92  can be slid onto the cassette  71  to read test strip results by aligning a sliding feature of the reader  92  with mating or corresponding rails  91  or another sliding feature in a cassette bottom  95 . The rail  91  may be located on a split line between the cassette top  77  and the cassette bottom  95  or another place on the cassette  71 . The rails and sliding feature additionally facilitate high precision alignment between the cassette  71  and the reader  92 . 
     When the cassette is in place within the reader  92 , a shroud  93  of the reader  92  is formed to block out light. 
       FIG. 30A-33  show a clip-on multiuse reader. The clip-on multiuse reader  97  has a reader top  97  attached to a reader bottom  104 . The reader top  97  has a user interface  55 . The reader bottom  104  has clips  98  which are attached via plastic hinge  102 . An alignment pin  82  extends outwards from the reader bottom  104 . Within the clip-on multiuse reader  97  includes a PCBA  79  with a battery  19  on a top surface. The reader bottom  104  has a carrier  17  with a light guide  88 . 
     A clip-on multiuse reader  97  can be clipped on to the cassette  71  by the clips  98  of the reader  97  which are received by a recess  99  on the cassette bottom  95 . The recess  99  is aligned with the windows  24  such that the light guide  88  of the reader bottom  104  is aligned with the windows  24  when the clip-on multiuse reader  97  is clipped onto the cassette  71 . To help with the alignment, at least one alignment pin  82  is received within a recess on the cassette top  77 . A shoulder  100  of the alignment pin  82  sets the height between the cassette  71  and the reader  97 . 
     In an alternate embodiment, the cassette windows  24  may be combined with the light guide  88  (carrier windows  40 ) such that both sets of the windows  24  and  40  that feature as a split light guide are formed as part of the carrier  17 . In this configuration, the cassette top  77  comprises a single window. As the clip-on reader is clipped down from the top face of the cassette, rather than sliding onto the cassette, the light guide features of the carrier can protrude out from the reader and can fit the form of the cassette window. The protruding light guide comprises the advantages of the split light guide in a single component taking the features of the light guide to the surface of the test strip and extend into the reader electronics (LEDs and detectors). In this configuration, the cassette top  77  provides a clear view of the test strip  13  when the reader is not attached, thereby allowing the user to visually determine the test result without the use of a reader. 
     The clip-on multiuse reader  97  can be removed from the cassette by squeezing the clips  98 , allowing the clips  98  to pivot on hinge  102 . 
     While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification(s). This application is intended to cover any variations uses or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth. 
     As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. The described embodiments are to be considered in all respects as illustrative only and not restrictive. 
     Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced. In the following claims, any means-plus-function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures. For example, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface to secure wooden parts together, in the environment of fastening wooden parts, a nail and a screw are equivalent structures.
     The following sections I-VII provide a guide to interpreting the present specification.   

     I. Terms 
     Different industry sectors and different countries use varying terminology to describe lateral flow assay products and devices. Some commonly used names include but are not limited to Lateral flow test (LFT), Lateral flow device (LFD), Lateral flow assay (LFA), Lateral flow immunoassay (LFIA), Lateral flow immunochromatographic assays, Dipstick, Pen-side test, Quick test, Rapid test, and Test strip. Accordingly, the present invention is not limited by any particular embodiment of lateral flow assay. 
     The term “sensor” is to be taken as synonymous with the terms “measurement sensor” or “illumination sensor”. 
     The term “result line”, “result lines” or “test result line” means the regions of the test strip where there are capture antibodies placed. These regions typically develop into test lines or control lines. 
     The term “test background” refers to a region of a test strip that is proximate or adjacent a result line or test line and which may be included in the regions of the test strip that are detected by the electronic lateral flow assay test reader. 
     The term “strip background” refers to a region of a test strip without capture antibodies and which is not included in the regions of the test strip that are detected by the electronic lateral flow assay test reader when detecting a result line. 
     The term “minimally reflective” means an attribute of the material that is configured to an illumination source wavelength in order to minimise the light reflected or emitted from the material. 
     The term a “viewing area” means one or more windows on the cassette. 
     The term “measurement area” means one or more windows on the reader. 
     The term “development area” means the area of the test strip where the test and/or control lines may develop. The development area can also comprise at least one area forming part or all of the strip background region 
     The term “test strip” is used herein in reference to the strip of material(s) utilised for a lateral flow assay test, which may comprise one or a combination of a sample pad, conjugate pad, a capillary bed having a development area, which itself may include zones comprising test and control zones inclusive of test and control lines, background regions, and a waste pad. Where the context of the description herein requires, the term is used for particular reference to the development area of the test strip. 
     The term “tolerance stack” would be appreciated by the person skilled in the art and is reference to the accumulation of error or uncertainty in a dimension due to uncertainty in each of a number of separate components or relationships. Accordingly, it may be considered the sum of uncertainties which make up the total uncertainty in a dimension. 
     The term “product” means any machine, manufacture and/or composition of matter, unless expressly specified otherwise. 
     The term “process” means any process, algorithm, method or the like, unless expressly specified otherwise. 
     Each process (whether called a method, algorithm or otherwise) inherently includes one or more steps, and therefore all references to a “step” or “steps” of a process have an inherent antecedent basis in the mere recitation of the term ‘process’ or a like term. Accordingly, any reference in a claim to a ‘step’ or ‘steps’ of a process has sufficient antecedent basis. 
     The term “invention” and the like mean “the one or more inventions disclosed in this specification”, unless expressly specified otherwise. 
     The terms “an embodiment”, “embodiment”, “embodiments”, “the embodiment”, “the embodiments”, “one or more embodiments”, “some embodiments”, “certain embodiments”, “one embodiment”, “another embodiment” and the like mean “one or more (but not all) embodiments of the disclosed invention(s)”, unless expressly specified otherwise. 
     The term “variation” of an invention means an embodiment of the invention, unless expressly specified otherwise. 
     A reference to “another embodiment” in describing an embodiment does not imply that the referenced embodiment is mutually exclusive with another embodiment (e.g., an embodiment described before the referenced embodiment), unless expressly specified otherwise. 
     The terms “including”, “comprising” and variations thereof mean “including but not limited to”, unless expressly specified otherwise. 
     The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise. 
     The term “plurality” means “two or more”, unless expressly specified otherwise. 
     The term “herein” means “in the present specification, including anything which may be incorporated by reference”, unless expressly specified otherwise. 
     The phrase “at least one of”, when such phrase modifies a plurality of things (such as an enumerated list of things), means any combination of one or more of those things, unless expressly specified otherwise. For example, the phrase “at least one of a widget, a car and a wheel” means either (i) a widget, (ii) a car, (iii) a wheel, (iv) a widget and a car, (v) a widget and a wheel, (vi) a car and a wheel, or (vii) a widget, a car and a wheel. The phrase “at least one of”, when such phrase modifies a plurality of things, does not mean “one of each of” the plurality of things. 
     Numerical terms such as “one”, “two”, etc. when used as cardinal numbers to indicate quantity of something (e.g., one widget, two widgets), mean the quantity indicated by that numerical term, but do not mean at least the quantity indicated by that numerical term. For example, the phrase “one widget” does not mean “at least one widget”, and therefore the phrase “one widget” does not cover, e.g., two widgets. 
     The phrase “based on” does not mean “based only on”, unless expressly specified otherwise. In other words, the phrase “based on” describes both “based only on” and “based at least on”. The phrase “based at least on” is equivalent to the phrase “based at least in part on”. 
     The term “represent” and like terms are not exclusive, unless expressly specified otherwise. For example, the term “represents” do not mean “represents only”, unless expressly specified otherwise. In other words, the phrase “the data represents a credit card number” describes both “the data represents only a credit card number” and “the data represents a credit card number and the data also represents something else”. 
     The term “whereby” is used herein only to precede a clause or other set of words that express only the intended result, objective or consequence of something that is previously and explicitly recited. Thus, when the term “whereby” is used in a claim, the clause or other words that the term “whereby” modifies do not establish specific further limitations of the claim or otherwise restricts the meaning or scope of the claim. 
     The term “e.g.” and like terms mean “for example”, and thus does not limit the term or phrase it explains. For example, in the sentence “the computer sends data (e.g., instructions, a data structure) over the Internet”, the term “e.g.” explains that “instructions” are an example of “data” that the computer may send over the Internet, and also explains that “a data structure” is an example of “data” that the computer may send over the Internet. However, both “instructions” and “a data structure” are merely examples of “data”, and other things besides “instructions” and “a data structure” can be “data”. 
     The term “i.e.” and like terms mean “that is”, and thus limits the term or phrase it explains. For example, in the sentence “the computer sends data (i.e., instructions) over the Internet”, the term “i.e.” explains that “instructions” are the “data” that the computer sends over the Internet. 
     Any given numerical range shall include whole and fractions of numbers within the range. For example, the range “1 to 10” shall be interpreted to specifically include whole numbers between 1 and 10 (e.g., 2, 3, 4, . . . 9) and non-whole numbers (e.g., 1.1, 1.2, . . . 1.9). 
     II. Determining 
     The term “determining” and grammatical variants thereof (e.g., to determine a price, determining a value, determine an object which meets a certain criterion) is used in an extremely broad sense. The term “determining” encompasses a wide variety of actions and therefore “determining” can include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” can include resolving, selecting, choosing, establishing, and the like. 
     The term “determining” does not imply certainty or absolute precision, and therefore “determining” can include estimating, extrapolating, predicting, guessing and the like. 
     The term “determining” does not imply that mathematical processing must be performed, and does not imply that numerical methods must be used, and does not imply that an algorithm or process is used. 
     The term “determining” does not imply that any particular device must be used. For example, a computer need not necessarily perform the determining. 
     III. Indication 
     The term “indication” is used in an extremely broad sense. The term “indication” may, among other things, encompass a sign, symptom, or token of something else. 
     The term “indication” may be used to refer to any indicia and/or other information indicative of or associated with a subject, item, entity, and/or other object and/or idea. 
     As used herein, the phrases “information indicative of” and “indicia” may be used to refer to any information that represents, describes, and/or is otherwise associated with a related entity, subject, or object. 
     Indicia of information may include, for example, a symbol, a code, a reference, a link, a signal, an identifier, and/or any combination thereof and/or any other informative representation associated with the information. 
     In some embodiments, indicia of information (or indicative of the information) may be or include the information itself and/or any portion or component of the information. In some embodiments, an indication may include a request, a solicitation, a broadcast, and/or any other form of information gathering and/or dissemination. 
     IV. Forms of Sentences 
     Where a limitation of a first claim would cover one of a feature as well as more than one of a feature (e.g., a limitation such as “at least one widget” covers one widget as well as more than one widget), and where in a second claim that depends on the first claim, the second claim uses a definite article “the” to refer to the limitation (e.g., “the widget”), this does not imply that the first claim covers only one of the feature, and this does not imply that the second claim covers only one of the feature (e.g., “the widget” can cover both one widget and more than one widget). 
     When an ordinal number (such as “first”, “second”, “third” and so on) is used as an adjective before a term, that ordinal number is used (unless expressly specified otherwise) merely to indicate a particular feature, such as to distinguish that particular feature from another feature that is described by the same term or by a similar term. For example, a “first widget” may be so named merely to distinguish it from, e.g., a “second widget”. Thus, the mere usage of the ordinal numbers “first” and “second” before the term “widget” does not indicate any other relationship between the two widgets, and likewise does not indicate any other characteristics of either or both widgets. For example, the mere usage of the ordinal numbers “first” and “second” before the term “widget” (1) does not indicate that either widget comes before or after any other in order or location; (2) does not indicate that either widget occurs or acts before or after any other in time; and (3) does not indicate that either widget ranks above or below any other, as in importance or quality. In addition, the mere usage of ordinal numbers does not define a numerical limit to the features identified with the ordinal numbers. For example, the mere usage of the ordinal numbers “first” and “second” before the term “widget” does not indicate that there must be no more than two widgets. 
     When a single device or article is described herein, more than one device/article (whether or not they cooperate) may alternatively be used in place of the single device/article that is described. Accordingly, the functionality that is described as being possessed by a device may alternatively be possessed by more than one device/article (whether or not they cooperate). 
     Similarly, where more than one device or article is described herein (whether or not they cooperate), a single device/article may alternatively be used in place of the more than one device or article that is described. For example, a plurality of computer-based devices may be substituted with a single computer-based device. Accordingly, the various functionality that is described as being possessed by more than one device or article may alternatively be possessed by a single device/article. 
     The functionality and/or the features of a single device that is described may be alternatively embodied by one or more other devices which are described but are not explicitly described as having such functionality/features. Thus, other embodiments need not include the described device itself, but rather can include the one or more other devices which would, in those other embodiments, have such functionality/features. 
     V. Disclosed Examples and Terminology Are Not Limiting 
     Neither the Title nor the Abstract in this specification is intended to be taken as limiting in any way as the scope of the disclosed invention(s). The title and headings of sections provided in the specification are for convenience only, and are not to be taken as limiting the disclosure in any way. 
     Numerous embodiments are described in the present application, and are presented for illustrative purposes only. The described embodiments are not, and are not intended to be, limiting in any sense. The presently disclosed invention(s) are widely applicable to numerous embodiments, as is readily apparent from the disclosure. One of ordinary skill in the art will recognise that the disclosed invention(s) may be practised with various modifications and alterations, such as structural, logical, software, and electrical modifications. Although particular features of the disclosed invention(s) may be described with reference to one or more particular embodiments and/or drawings, it should be understood that such features are not limited to usage in the one or more particular embodiments or drawings with reference to which they are described, unless expressly specified otherwise. 
     The present disclosure is not a literal description of all embodiments of the invention(s). Also, the present disclosure is not a listing of features of the invention(s) which must be present in all embodiments. 
     Devices that are described as in communication with each other need not be in continuous communication with each other, unless expressly specified otherwise. On the contrary, such devices need only transmit to each other as necessary or desirable, and may actually refrain from exchanging data most of the time. For example, a machine in communication with another machine via the Internet may not transmit data to the other machine for long period of time (e.g. weeks at a time). In addition, devices that are in communication with each other may communicate directly or indirectly through one or more intermediaries. 
     A description of an embodiment with several components or features does not imply that all or even any of such components/features are required. On the contrary, a variety of optional components are described to illustrate the wide variety of possible embodiments of the present invention(s). Unless otherwise specified explicitly, no component/feature is essential or required. 
     Although process steps, operations, algorithms or the like may be described in a particular sequential order, such processes may be configured to work in different orders. In other words, any sequence or order of steps that may be explicitly described does not necessarily indicate a requirement that the steps be performed in that order. The steps of processes described herein may be performed in any order practical. Further, some steps may be performed simultaneously despite being described or implied as occurring non-simultaneously (e.g., because one step is described after the other step). Moreover, the illustration of a process by its depiction in a drawing does not imply that the illustrated process is exclusive of other variations and modifications thereto, does not imply that the illustrated process or any of its steps are necessary to the invention(s), and does not imply that the illustrated process is preferred. 
     Although a process may be described as including a plurality of steps, that does not imply that all or any of the steps are preferred, essential or required. Various other embodiments within the scope of the described invention(s) include other processes that omit some or all of the described steps. Unless otherwise specified explicitly, no step is essential or required. 
     Although a process may be described singly or without reference to other products or methods, in an embodiment the process may interact with other products or methods. For example, such interaction may include linking one business model to another business model. Such interaction may be provided to enhance the flexibility or desirability of the process. 
     Although a product may be described as including a plurality of components, aspects, qualities, characteristics and/or features, that does not indicate that any or all of the plurality are preferred, essential or required. Various other embodiments within the scope of the described invention(s) include other products that omit some or all of the described plurality. 
     An enumerated list of items (which may or may not be numbered) does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. Likewise, an enumerated list of items (which may or may not be numbered) does not imply that any or all of the items are comprehensive of any category, unless expressly specified otherwise. For example, the enumerated list “a computer, a laptop, a PDA” does not imply that any or all of the three items of that list are mutually exclusive and does not imply that any or all of the three items of that list are comprehensive of any category. 
     An enumerated list of items (which may or may not be numbered) does not imply that any or all of the items are equivalent to each other or readily substituted for each other. 
     All embodiments are illustrative, and do not imply that the invention or any embodiments were made or performed, as the case may be. 
     VI. Computing 
     It will be readily apparent to one of ordinary skill in the art that the various processes described herein may be implemented by, e.g., appropriately programmed general purpose computers, special purpose computers and computing devices. Typically a processor (e.g., one or more microprocessors, one or more micro-controllers, one or more digital signal processors) will receive instructions (e.g., from a memory or like device), and execute those instructions, thereby performing one or more processes defined by those instructions. 
     A “processor” means one or more microprocessors, central processing units (CPUs), computing devices, micro-controllers, digital signal processors, or like devices or any combination thereof. 
     Thus a description of a process is likewise a description of an apparatus for performing the process. The apparatus that performs the process can include, e.g., a processor and those input devices and output devices that are appropriate to perform the process. 
     Further, programs that implement such methods (as well as other types of data) may be stored and transmitted using a variety of media (e.g., computer readable media) in a number of manners. In some embodiments, hard-wired circuitry or custom hardware may be used in place of, or in combination with, some or all of the software instructions that can implement the processes of various embodiments. Thus, various combinations of hardware and software may be used instead of software only. 
     The term “computer-readable medium” refers to any medium, a plurality of the same, or a combination of different media, that participate in providing data (e.g., instructions, data structures) which may be read by a computer, a processor or a like device. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks and other persistent memory. Volatile media include dynamic random access memory (DRAM), which typically constitutes the main memory. Transmission media include coaxial cables, copper wire and fibre optics, including the wires that comprise a system bus coupled to the processor. Transmission media may include or convey acoustic waves, light waves and electromagnetic emissions, such as those generated during radio frequency (RF) and infra-red (IR) data communications. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read. 
     Various forms of computer readable media may be involved in carrying data (e.g. sequences of instructions) to a processor. For example, data may be (i) delivered from RAM to a processor; (ii) carried over a wireless transmission medium; (iii) formatted and/or transmitted according to numerous formats, standards or protocols, such as Ethernet (or IEEE 802.3), SAP, ATP, Bluetooth™, and TCP/IP, TDMA, CDMA, and 3G; and/or (iv) encrypted to ensure privacy or prevent fraud in any of a variety of ways well known in the art. 
     Thus, a description of a process is likewise a description of a computer-readable medium storing a program for performing the process. The computer-readable medium can store (in any appropriate format) those program elements which are appropriate to perform the method. 
     Just as the description of various steps in a process does not indicate that all the described steps are required, embodiments of an apparatus include a computer/computing device operable to perform some (but not necessarily all) of the described process. 
     Likewise, just as the description of various steps in a process does not indicate that all the described steps are required, embodiments of a computer-readable medium storing a program or data structure include a computer-readable medium storing a program that, when executed, can cause a processor to perform some (but not necessarily all) of the described process. 
     Where databases are described, it will be understood by one of ordinary skill in the art that (i) alternative database structures to those described may be readily employed, and (ii) other memory structures besides databases may be readily employed. Any illustrations or descriptions of any sample databases presented herein are illustrative arrangements for stored representations of information. Any number of other arrangements may be employed besides those suggested by, e.g., tables illustrated in drawings or elsewhere. Similarly, any illustrated entries of the databases represent exemplary information only; one of ordinary skill in the art will understand that the number and content of the entries can be different from those described herein. Further, despite any depiction of the databases as tables, other formats (including relational databases, object-based models and/or distributed databases) could be used to store and manipulate the data types described herein. Likewise, object methods or behaviours of a database can be used to implement various processes, such as the described herein. In addition, the databases may, in a known manner, be stored locally or remotely from a device which accesses data in such a database. 
     Various embodiments can be configured to work in a network environment including a computer that is in communication (e.g., via a communications network) with one or more devices. The computer may communicate with the devices directly or indirectly, via any wired or wireless medium (e.g. the Internet, LAN, WAN or Ethernet, Token Ring, a telephone line, a cable line, a radio channel, an optical communications line, commercial on-line service providers, bulletin board systems, a satellite communications link, a combination of any of the above). Each of the devices may themselves comprise computers or other computing devices that are adapted to communicate with the computer. Any number and type of devices may be in communication with the computer. 
     In an embodiment, a server computer or centralised authority may not be necessary or desirable. For example, the present invention may, in an embodiment, be practised on one or more devices without a central authority. In such an embodiment, any functions described herein as performed by the server computer or data described as stored on the server computer may instead be performed by or stored on one or more such devices. 
     Where a process is described, in an embodiment the process may operate without any user intervention. In another embodiment, the process includes some human intervention (e.g., a step is performed by or with the assistance of a human). 
     It should be noted that where the terms “server”, “secure server” or similar terms are used herein, a communication device is described that may be used in a communication system, unless the context otherwise requires, and should not be construed to limit the present invention to any particular communication device type. Thus, a communication device may include, without limitation, a bridge, router, bridge-router (router), switch, node, or other communication device, which may or may not be secure. 
     It should also be noted that where a flowchart is used herein to demonstrate various aspects of the invention, it should not be construed to limit the present invention to any particular logic flow or logic implementation. The described logic may be partitioned into different logic blocks (e.g., programs, modules, functions, or subroutines) without changing the overall results or otherwise departing from the true scope of the invention. Often, logic elements may be added, modified, omitted, performed in a different order, or implemented using different logic constructs (e.g., logic gates, looping primitives, conditional logic, and other logic constructs) without changing the overall results or otherwise departing from the true scope of the invention. 
     Various embodiments of the invention may be embodied in many different forms, including computer program logic for use with a processor (e.g., a microprocessor, microcontroller, digital signal processor, or general purpose computer and for that matter, any commercial processor may be used to implement the embodiments of the invention either as a single processor, serial or parallel set of processors in the system and, as such, examples of commercial processors include, but are not limited to Merced™, Pentium™, Pentium II™, Xeon™, Celeron™, Pentium Pro™, Efficeon™, Athlon™, AMD™ and the like), programmable logic for use with a programmable logic device (e.g., a Field Programmable Gate Array (FPGA) or other PLD), discrete components, integrated circuitry (e.g., an Application Specific Integrated Circuit (ASIC)), or any other means including any combination thereof. In an exemplary embodiment of the present invention, predominantly all of the communication between users and the server is implemented as a set of computer program instructions that is converted into a computer executable form, stored as such in a computer readable medium, and executed by a microprocessor under the control of an operating system. 
     Computer program logic implementing all or part of the functionality where described herein may be embodied in various forms, including a source code form, a computer executable form, and various intermediate forms (e.g., forms generated by an assembler, compiler, linker, or locator). Source code may include a series of computer program instructions implemented in any of various programming languages (e.g., an object code, an assembly language, or a high-level language such as Fortran, C, C++, JAVA, or HTML. Moreover, there are hundreds of available computer languages that may be used to implement embodiments of the invention, among the more common being Ada; Algol; APL; awk; Basic; C; C++; Conol; Delphi; Eiffel; Euphoria; Forth; Fortran; HTML; Icon; Java; Javascript; Lisp; Logo; Mathematica; MatLab; Miranda; Modula-2; Oberon; Pascal; Perl; PL/I; Prolog; Python; Rexx; SAS; Scheme; sed; Simula; Smalltalk; Snobol; SQL; Visual Basic; Visual C++; Linux and XML.) for use with various operating systems or operating environments. The source code may define and use various data structures and communication messages. The source code may be in a computer executable form (e.g., via an interpreter), or the source code may be converted (e.g., via a translator, assembler, or compiler) into a computer executable form. 
     The computer program may be fixed in any form (e.g., source code form, computer executable form, or an intermediate form) either permanently or transitorily in a tangible storage medium, such as a semiconductor memory device (e.g, a RAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM or DVD-ROM), a PC card (e.g., PCMCIA card), or other memory device. The computer program may be fixed in any form in a signal that is transmittable to a computer using any of various communication technologies, including, but in no way limited to, analog technologies, digital technologies, optical technologies, wireless technologies (e.g., Bluetooth), networking technologies, and inter-networking technologies. The computer program may be distributed in any form as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the communication system (e.g., the Internet or World Wide Web). 
     Hardware logic (including programmable logic for use with a programmable logic device) implementing all or part of the functionality where described herein may be designed using traditional manual methods, or may be designed, captured, simulated, or documented electronically using various tools, such as Computer Aided Design (CAD), a hardware description language (e.g., VHDL or AHDL), or a PLD programming language (e.g., PALASM, ABEL, or CUPL). Hardware logic may also be incorporated into display screens for implementing embodiments of the invention and which may be segmented display screens, analogue display screens, digital display screens, CRTs, LED screens, Plasma screens, liquid crystal diode screen, and the like. 
     Programmable logic may be fixed either permanently or transitorily in a tangible storage medium, such as a semiconductor memory device (e.g., a RAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM or DVD-ROM), or other memory device. The programmable logic may be fixed in a signal that is transmittable to a computer using any of various communication technologies, including, but in no way limited to, analog technologies, digital technologies, optical technologies, wireless technologies (e.g., Bluetooth), networking technologies, and internetworking technologies. The programmable logic may be distributed as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the communication system (e.g., the Internet or World Wide Web). 
     “Comprises/comprising” and “includes/including” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words ‘comprise’, ‘comprising’, ‘includes’, ‘including’ and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.