US Patent 9341620 Microfluidics based assay device

A subtractive corrective assay device and methodology, whereby ail required binding and label detection reagents are initially located within the detection zone. Application of a magnetic field is used to selectively remove bound label from the detection zone by means of paramagnetic particles. The relationship between measured label concentration before and after the application of a magnetic field within the detection zone is used to accurately measure analyte concentration within the sample.