Application of Carbon-Nanotube-Composite Japanese Washi Paper to Authentication Systems

We propose applying carbon-nanotube-composite Japanese washi paper (CNT-washi) to a secure authentication system. CNT-washi is easily made by a simple fabrication method. We used three-dimensional Raman spectrum mapping patterns from CNT-washi as a special "key" for a secure authentication system. CNTs automatically form complex patterns in the paper, and it is very difficult to copy these patterns owing to their nanometer size. We observed Raman spectra at divided areas of each CNT-washi sample and prepared mapping patterns. The observed pattern of a sample was different from those of the other samples because the variety or concentration of the CNTs differs between samples. We calculated correlation coefficients between the mapping data of the prepared samples. Experimental results indicate that the patterns of our CNT-washi can be used as a "key" for authentication systems. (C) 2009 The Japan Society of Applied Physics