| abstract |
Microparticles (8) includes an optical substrate (10) having at least one diffraction grating (12) disposed therein. The grating (12) having a plurality of colocated pitches Λ which represent a unique identification digital code that is detected when illuminated by incident light (24). The incident light (24) may be directed transversely from the side of the substrate (10) with a narrow band (single wavelength) or multiple wavelength source, in which case the code is represented by a spatial distribution of light or a wavelength spectrum, respectively. The code may be digital binary or may be other numerical bases. The micro-particles (8) can provide a large number of unique codes, e.g., greater than 67 million codes, and can withstand harsh environments. The microparticles (8) are functionalized by coating them with a material/substance of interest, which are then used to perform multiplexed experiments involving chemical processes, e.g., DNA testing and combinatorial chemistry. |