Patent ID: 7550267

Claim:
A method for detecting the presence of analyte particles in an analyte fluid comprising: (a) providing the analyte fluid comprising the analyte particles; (b) providing a diffusion fluid comprising binding particles capable of binding with the analyte particles; (c) flowing the analyte fluid and the diffusion fluid in adjacent laminar flow through a microfluidic channel; (d) allowing the analyte particles to diffuse into the diffusion fluid and bind with the binding particles to form analyte/binding particle complexes; (e) allowing the analyte/binding particle complexes to cross-link to form cross-linked aggregates; and (f) detecting the presence of the analyte particles and the cross-linked aggregates, wherein: each of the binding particles is capable of binding with more than one analyte particle; each of the analyte particles is capable of binding with more than one binding particle; the non-aggregated analyte/binding particle complexes and the analyte particles are at least the same order of magnitude in size and have diffusion coefficients that are essentially the same; and the cross-linked aggregates have a diffusion coefficient that is at least two times greater than the diffusion coefficients of the non-aggregated analyte/binding particle complexes and the analyte particles.