Patent ID: 7670786

Claim:
A method for detecting the presence or quantity of an analyte residing in a test sample, said method comprising: i) providing a membrane-based device, said device comprising a porous membrane that defines a detection zone and is in fluid communication with: detection probes that comprise non-magnetic particles conjugated with a first specific binding member and labeled with a detectable substance that is configured to emit a detection signal, the first specific binding member being capable of binding with the analyte; calibration probes that comprise magnetic particles labeled with a detectable substance that is configured to produce a calibration signal; and non-labeled magnetic particles conjugated with a second binding member, the second binding member also being capable of binding with the analyte; ii) contacting said detection probes, said calibration probes, and said non-labeled magnetic particles with the test sample so that complexes are formed between said detection probes, analyte, and non-labeled magnetic particles; iii) immobilizing said calibration probes and said complexes within said detection zone using a magnetic device; iv) exciting said detection probes and said calibration probes within said detection zone, wherein said excitation causes said detection probes to emit said detection signal and said calibration probes to emit said calibration signal; v) measuring the intensity of the detection signal at a first emission wavelength and the intensity of the calibration signal at a second emission wavelength; and vi) comparing the intensity of the detection signal to the calibration signal, wherein the amount of the analyte within the test sample is proportional to the intensity of the detection signal calibrated by the intensity of the calibration signal.