Encoding and decoding nanoscale thermal barcodes for ultrahigh capacity identification systems

An ultrahigh capacity coding system is created based on the solid to liquid phase changes of a variety of nanoparticles, which are designed and prepared with sharp, discrete melting peaks and encapsulated inside nonmelting shells. A mixture of such thermally-active nanoparticles at designed ratio can be embedded inside an object as a nanoscale barcode that can be decoded by differential thermal scan. The coding capacity depends on the number of melting peaks, which in turn depends on nanoparticle compositions. A coding system with 50 different compositions can generate over 1015 thermal barcodes, sufficient for many identification applications. © 2009 American Institute of Physics.