Patent ID: 7291504

Claim:
An assay method comprising: (i) providing a planar array of particles randomly-positioned with respect to particle type, where different types of particles are differently encoded by incorporation of an optically detectable characteristic into the particles that permits said differently encoded particles to be distinguished, and wherein said differently encoded particles have different binding molecules attached thereto; (ii) determining the spatial coordinates of particular particle types within the planar array; (iii) contacting said array of particles with a solution such that, if a particular type of analyte is present in said solution, said analyte binds to the corresponding binding molecules of said particles and the binding of said analyte is indicated by an optically detectable signal; (iv) determining the presence of any such bound analyte by determining the presence of said optically detectable signal; and (v) identifying said optically detectable characteristic of particles having binding molecules bound to an analyte, without moving or separating said particles being interrogated from other particles in the array, by correlating the spatial coordinates of said particles with the location of the optically detectable signals in order to identify said binding molecules bound to an analyte.