Recently, the research team of researcher Shao Yuchuan from Shanghai Institute of Optical Precision Machinery, Chinese Academy of Sciences, has proposed a new scheme to utilize the photothermal effect of gold nanoparticles for the preparation of optical PUFs, and the related research results are summarized as "Physical Unclonable Functions based on the Photothermal Effect of Gold Nanoparticles". The research results were published in ACS Applied Materials & Interfaces under the title of "Photothermal Effect of Gold Nanoparticles".
Currently, common security labels can be easily imitated due to their fixed production process. Physical Unclonable Functions (PUFs) utilize the uncontrollable preparation deviation of materials during the preparation process, which can generate unique and unrepeatable response signals as anti-counterfeiting codes. Just as there are no two identical leaves in the world, even a manufacturer cannot make two identical PUFs. although optical PUFs have attracted a lot of attention due to their high encoding capacity and high response contrast, they still face many challenges: the response signals of scattering PUFs are unstable, the lifespan of fluorescent PUFs is threatened by fluorescence bleaching, and the authentication system of Raman PUFs is complicated and requires expensive spectral decoding equipment. The next generation of optical PUFs will require immuno-immunoprecipitation. Next-generation optical PUFs need the ability of immunofluorescence and Raman excitation, thus fundamentally eliminating the influence of the material's own defects on the safety performance of optical PUFs.
The researchers propose a new scheme to prepare optical PUFs utilizing the nanogold photothermal effect. The scheme starts with optimizing the surface density and response intensity of fused silica subsurface defects, and uses gold nanoparticles with obvious photothermal effect to replace the subsurface defects and generate response signals with sufficiently high response contrast. The optimal surface density of gold nanoparticles was achieved by optimizing the preparation process to maximize the encoding capability of the PUF. The prepared optical PUF not only meets the PUF performance requirements such as uniqueness, reliability, and bit uniformity, but its encoding secret key also passes the NIST random number test to verify its randomness. This work provides a strong support for the realization of the application of photothermal effect on optical PUF.
Fig. 1 Schematic principle of optical PUF based on nanogold photothermal properties
