Interactive test device and apparatus with timing mechanism
A system comprised of an apparatus and a test device is described. The test device and the apparatus are designed to interact to determine the presence or absence of an analyte of interest in a sample placed on the test device. The test device and apparatus interact to provide a timer feature for determining a test device specific adjustable cut-off value that is used to ascertain whether signal from a test line in the device corresponds to a positive or negative results, irrespective of the time elapsed since placement of sample on the test device. The adjustable cut-off value renders the system relatively insensitive to incubation time of the test device, where if the incubation time is shorter or longer than needed for accuracy of a test result, the analyzer will report an invalid result, thus preventing the reporting of an incorrect (false negative or false positive) result.
1. A system, comprising:
a test device comprising:
(a) a label zone comprising
(i) a first population of mobilizable, detectable particles for specific binding to a test analyte in a sample; and
(ii) a second population of mobilizable, detectable particles for specific binding to a non-test analyte but not to the test analyte;
(b) a first detection site at a first position comprising a first binding member having specific binding affinity for detectable particles in the first population bound to the test analyte; and
(c) a second detection site at a second position that is separate from the first position, the second detection site comprising a second binding member having specific binding affinity for detectable particles in the second population bound to the non-test analyte; and
an analyzer comprising:
(1) a drawer dimensioned to receive the test device,
(2) an optical system for detection of a signal generated from the first population of mobilizable, detectable particles at the first position and the second population of mobilizable, detectable particles at the second position when each population reaches a specific and separate position on the test device,
(3) a motor to move a detector in the optical system from the first detection site to the second detection site,
(4) a processor communicatively coupled with the optical system to receive the signal from the detector and to evaluate a ratio of a signal detected from all or a portion of the first population of mobilizable, detectable particles to a cut-off value to determine a presence or an absence of analyte in the sample based on the ratio, and
(5) a memory storing the cut-off value, wherein the cut-off value is an exponentially transformed signal from all or a portion of the second population of mobilizable, detectable particles, adjusted by a constant value empirically determined for a manufacturing lot comprising the test device.
2. The system of claim 1 , wherein the signal from all or a portion of the first population of mobilizable, detectable particles is used by the processor to provide a quantitative or semi-quantitative amount of analyte present in the sample.
3. The system of claim 1 , wherein signal from the second population of mobilizable, detectable particles is mathematically transformed by the processor in the analyzer to provide a transformed signal.
4. The system of claim 3 , wherein the signal from the second population of mobilizable, detectable particles is mathematically transformed by the processor using an exponential transformation.
5. The system of claim 4 , wherein the exponential transformation is selected from an exponential value of between 1.3-1.8.
6. The system of claim 1 , wherein the test device is a lateral flow immunoassay.
7. The system of claim 6 , wherein one or both of the first population of mobilizable, detectable particles and the second population of mobilizable, detectable particles is comprised of particles comprised of a fluorescing lanthanide compound.
8. The system of claim 7 , wherein the fluorescing lanthanide compound is europium.