Lateral flow immunoassay test reader and method of use

Abstract

A reader for a lateral flow test device includes a tray or drawer, extendable from the reader, which receives the test device. The tray includes a calibration test pattern affixed or printed thereon placed proximate to the test device and in alignment with the axis of the test device. As the tray is closed and the test device is inserted to the reader, the calibration test pattern is first read by an optics unit including a photodiode. The resulting photodiode output provides a calibration curve S that the reader then uses to correct for any non-linear response of the reader's optical or electronic systems, thus insuring that every reader will yield the same readout for a given test cartridge, despite reader-to-reader variations or reader degradation with time. One use of the reader is for detection of SARS-CoV-2 infection.

We claim: 
     
         1 . A method for reading a lateral flow test device having one or more test lines and a control line with a reader having electronics and an optics unit and a tray extendable from the reader from an open position in which the test device is placed in the tray to a closed position whereby the test device is read by the optics unit, comprising the steps of:
 reading a calibration test pattern placed on the tray with the optics unit, the optics unit including a photodiode;   performing a self-test of the reader's electro-optical system, wherein the self-test includes generating a calibration curve S characterizing any non-linear response of the electro-optical system; and   reading the test and control lines of the test device with the optics unit, including using the calibration curve S to convert photodiode output values to % absorbance values.   
     
     
         2 . The method of  claim 1 , wherein the calibration test pattern is in the form of a linear series of bands of known, graded optical intensities, each of the bands oriented perpendicular to the axis of the test device. 
     
     
         3 . The method of  claim 2 , wherein the linear series of bands takes the form of at least five bands of known graded optical intensities. 
     
     
         4 . The method of  claim 2 , wherein the linear series of bands takes the form of at least ten bands of known graded optical intensities. 
     
     
         6 . The method of  claim 2 , wherein the calibration test pattern is printed on a material and the material is placed in a designated location on an upper surface of the tray. 
     
     
         7 . The method of  claim 1 , wherein the optics unit comprises a diode laser generating a light output, a line generator converting the light output of the diode laser to a line format, and the photodiode, the photodiode reading the intensity of the laser light reflected from the test device. 
     
     
         8 . The method of  claim 7 , wherein the line format of the laser light is oriented perpendicular to the axis of the test device and in the same orientation of each of the bands of the calibration optical test pattern. 
     
     
         9 . The method of  claim 1 , wherein the test device comprises a test strip. 
     
     
         10 . The method of  claim 1 , wherein the test device comprises a cartridge containing a test strip. 
     
     
         11 . The method of  claim 1 , wherein the test device includes a test strip configured to test for presence of antibodies to the SARS-CoV-2 virus. 
     
     
         12 . A method for calibrating a reader for a lateral flow test device, the reader including an optics unit including a photodiode receiving light reflected from a test strip provided with the test device, comprising the steps of:
 a) scanning in the reader a calibration test pattern;   b) acquiring photodiode output values during the scanning step a);   c) optionally inverting the output values;   d) calculating average peak heights Ai in the output values;   e) storing the results of step d) as an array of peak heights and linear position data [Ai, Pi], the linear position data Pi indicative of incremental linear positions at which the calibration test pattern was scanned in step a); and   f) fitting a spline curve S to the array data and saving the equations for the spline curve S, wherein the spine curve S characterizes any non-linear response of the optics system or associated electronics.   
     
     
         13 . The method of  claim 12 , wherein the scanning step a) comprises manual insertion of a tray carrying the test device into the reader, and wherein the tray includes the calibration test pattern. 
     
     
         14 . The method of  claim 12 , wherein the test device includes a test strip configured to test for presence of antibodies to the SARS-CoV-2 virus. 
     
     
         15 . The method of  claim 12 , wherein the calibration test pattern is in the form of a linear series of bands of known, graded optical intensities, each of the bands oriented perpendicular to a long axis of the test device. 
     
     
         16 . The method of  claim 12 , wherein the calibration test pattern is printed on a material and the material affixed to the tray in alignment with the axis of the test device. 
     
     
         17 . A method of reading a lateral flow test device with a reader, the reader including an optics unit including a photodiode receiving light reflected from a test strip provided with the test device, comprising the steps of:
 a) scanning with the reader the test strip;   b) acquiring photodiode output values during the scanning step a);   c) optionally inverting the output values;   d) converting the photodiode output values to % absorbance values using equations for a spline curve S, wherein the spine curve S characterizes any non-linear response of the optics unit or associated electronics, and wherein spline curve S is generated during calibration of the optics unit prior to scanning step a);   e) identifying peaks in normalized absorbance data;   f) assigning labels to the peaks identified in step e);   g) applying local baseline corrections and calculating peak areas for each of the labeled peaks of step f); and   h) calculating ratios of peak areas associated with test lines of the test device to a control line of the test device.   
     
     
         18 . The method of  claim 17 , wherein the spline curve S is obtained in a calibration step performed immediately prior to the scanning step a). 
     
     
         19 . The method of  claim 18 , wherein the spline curve S is obtained from performing the procedure of  claim 1 . 
     
     
         20 . The method of  claim 17 , wherein the scanning step a) comprises manual insertion of a tray carrying the test device into the reader. 
     
     
         21 . The method of  claim 17 , wherein the test device includes a test strip configured to test for presence of antibodies to the SARS-CoV-2 virus. 
     
     
         22 . The method of  claim 1 , further comprising the steps of transmitting the results of reading the test device to a remote computing device. 
     
     
         23 . The method of  claim 22 , wherein the remote computing device is a smart phone. 
     
     
         24 . The method of  claim 22 , wherein the remote computing devices anonymizes the results. 
     
     
         25 . The method of  claim 24 , further comprising the step of transmitting the anonymized test results to a mineable database. 
     
     
         26 . A tray holding a lateral flow test device and configured for movement between open and inserted positions relative to a reader for reading the test device, the reader further including a ratchet pawl and a spring, the tray comprising:
 an upper surface, the upper surface having features for receiving and holding the test device;   a set of ratchet teeth formed on the tray,   wherein the pawl and spring of the reader are positioned so as to bias the pawl into engagement with the ratchet teeth;   the tray further includes a first feature disengaging the pawl from the set of ratchet teeth upon complete insertion of the tray into the reader and enabling the tray to be withdrawn from the reader; wherein when the tray is in intermediate positions between the open and inserted position the pawl, spring and ratchet teeth prevent retraction of the tray from the reader.   
     
     
         27 . The tray of  claim 26 , wherein the upper surface of the tray further comprises a calibration test pattern. 
     
     
         28 . The tray of  claim 26 , wherein the upper surface of the tray further comprises a encoder pattern. 
     
     
         29 . A tray configured to receive a lateral flow test device having an axis and facilitate insertion of the test device into and out of a reader having an optics unit, comprising:
 structure holding the test device in the tray, and   an optical calibration pattern on the tray in alignment with the axis of the test device.   
     
     
         30 . The tray of  claim 29 , further comprising an optical encoder affixed to the tray. 
     
     
         31 . The tray of  29 , wherein the optical encoder is affixed to platform positioning the optical encoder such that the optical encoder is moved adjacent to an optical reader for the encoder within the reader when the tray is moved into the reader. 
     
     
         32 . The tray of  claim 29 , wherein the calibration test pattern is printed and affixed to an upper surface of the tray in a designated position on the tray proximate to and in alignment with the axis of the test device. 
     
     
         33 . The tray of  claim 32 , wherein the calibration test pattern comprises a series of bands of graduated intensity oriented perpendicular to the axis of the test device. 
     
     
         34 . The tray of  claim 29 , wherein the tray further comprise a structure activating a first position switch within the reader to turn on the optics unit when the tray is inserted into the reader and a second position switch within the reader to turn off the optics unit when the tray is withdrawn from the reader. 
     
     
         35 . The tray of  34 , wherein the structure comprises a ramp formed in the tray. 
     
     
         36 . An accessory to a lateral flow assay reader having (1) a moveable tray holding a test device having one or more test lines and (2) an optics unit for reading the test device, the tray moveable from open and closed positions, the accessory unit comprising:
 a structure holding the reader, and   an electro-mechanical system engaging the tray and moving the tray and test device into the reader between the open and closed positions in a programmed manner such that the test device is positioned proximate to the optics unit such that at least one of the one or more test lines is read repeatedly for a period of time by the optics unit;   whereby the reader is able to record changes in the color intensity of the one or more test lines over time.   
     
     
         37 . The accessory of  claim 36 , wherein the test device comprises lateral flow test device having an axis and one or more test lines and a control line oriented perpendicular to the axis, and wherein the reader comprises:
 a housing enclosing electronics and the optics unit configured for reading one or more test lines and the control line of the test device;   wherein the tray is extendable from the housing between a closed position and an open position,
 wherein the tray is adapted to receive the test device when the tray is extended to the open position, and wherein when the test device is placed in the tray and the tray moved to a closed position the one or more test lines and control line are read by the optics unit; and 
 wherein the tray further includes a surface, the surface provided with an optical calibration test pattern spaced from the test device and positioned in alignment with the axis of the test device, the test pattern facilitating performance of a self-test of the optics unit upon movement of the tray from the open position to the closed position and immediately before the test device is read. 
   
     
     
         38 . The accessory of  claim 37 , wherein the test device include at least two test lines, and wherein the programmable movement moves the tray such that both test lines are positioned proximate to the optics unit enabling the at least two test lines to read repeatedly for a period of time by the optics unit. 
     
     
         39 . The accessory of  37 , wherein the optics unit includes a photodiode reading the at least one test lines and a memory storing photodiode output as a function of time while the movement of the tray is in stopped condition. 
     
     
         40 . The accessory of  claim 36 , wherein the accessory further comprises a QR code reader. 
     
     
         41 . The accessory of  claim 40 , wherein the QR code reader is positioned within the accessory and oriented such that it can read a QR code provided on the test device when the test device is held in the accessory. 
     
     
         42 . A system, comprising, a lateral flow assay reader, a test device having a bottom surface, and the accessory of  claim 36 , and further comprising:
 a QR code reader in the accessory, and   a sticker containing a QR code, wherein the sticker is sized and shaped, or provided with a guide, so as to enable a user to attach the sticker to the bottom surface of the test device such that the QR code is placed in a predetermined position on the bottom surface of the test device.   
     
     
         43 . The system of  claim 42 , wherein the reader has a bottom surface having an aperture formed therein wherein the QR code is applied to the test device in a position in alignment with the aperture enabling reading of the QR code by the QR code reader within the accessory. 
     
     
         44 . The system of  claim 43 , wherein the sticker has a width substantially equal to the width of the test device and wherein the QR code is placed on the sticker a distance from one edge thereof such that when the one end thereof is aligned with the end of the test device and affixed thereat the QR code is in the predetermined position.