A method for fabricating microparticles. The method includes providing a removable substrate that has a photosensitive material. The substrate has a plurality of inner regions. Each inner region surrounds a corresponding outer region. The method also includes providing at least one optically detectable...http://www.google.com.au/patents/US7796333?utm_source=gb-gplus-sharePatent US7796333 - Encoded microparticles and a method for fabricating
