Patent ID: 7709212

Claim:
A method for detecting the presence or amount of an analyte in a sample, said method comprising: (a) applying to a porous surface a first binding component comprising particles having attached thereto a binding substance that specifically binds to said analyte; (b) applying said sample to said porous surface; (c) applying to said porous surface a second binding component comprising detectably labelled particles; and (d) detecting a signal produced by said detectably labelled particles on said porous surface which is indicative of the presence and/or amount of said analyte in said sample; wherein said porous surface comprises one or more holes or openings; wherein said holes or openings allow unbound second binding component but not said first binding component to pass through said surface; wherein said first binding component and said analyte bind to each other to form a first binding complex; wherein said detectably labelled particles have attached thereto a binding substance that specifically binds to said first binding complex, such that said second binding component and said first binding complex bind to each other to form a second binding complex; wherein the first binding complex and second binding complex are retained on the porous surface; and wherein contact between the particles of the first binding component with holes or openings of the porous surface does not prevent second binding component that is not present in a second binding complex from passing through the same holes or openings.