Patent ID: 7271007

Claim:
A method for determining presence or concentration of sample analyte particles in an analyte fluid, the method comprising: a) adding additional analyte particles labeled with a detectable marker to said analyte fluid to provide a predetermined concentration or amount of labeled analyte particles in said analyte fluid; b) providing a diffusion fluid containing binding particles capable of binding to said sample analyte particles and said labeled analyte particles; c) providing a laminar flow channel comprising an analyte stream inlet and a diffusion stream inlet; d) flowing said analyte fluid into said analyte stream inlet as an analyte stream, and flowing said diffusion fluid into said diffusion stream inlet as a diffusion stream whereby said analyte and diffusion streams flow in adjacent laminar flow; e) allowing diffusion between said analyte and diffusion streams; f) detecting a diffusion profile in said channel formed by said labeled analyte particles; g) determining from said diffusion profile the presence or concentration of said sample analyte particles.