An assay stick 7 includes a transparent reaction vessel or tube 14 having one or more microbeads 8 disposed therein. The microbeads 8 have a plurality of unique identification digital codes based on a diffraction grating 12 disposed therein that are detected when illuminated by incident light 24. The...http://www.google.fr/patents/US20040126875?utm_source=gb-gplus-shareBrevet US20040126875 - Assay stick
