Flexible and Biocompatible Physical Unclonable Function Anti‐Counterfeiting Label

Abstract

Optical physical unclonable functions (PUFs) have been proven to be one of the most effective anti‐counterfeiting strategies. However, optical PUFs endowed with flexibility and biocompatibility have not been developed, limiting their application scenarios. Herein, biocompatible and flexible optical PUF labels are developed by randomly embedding microdiamonds in silk fibroin films. The PUF labels can be conformally attached onto the surface of complex shaped objects, providing the desired protection against fake and interior products. In this system, silk fibroin films serve as a flexible and biocompatible substrate, while the Raman signal of the microdiamonds serves as response of the excitation. The extremely high stability and random distribution of the microdiamonds ensure the performance of PUFs, and the maximum encoding capability of 210000 is finally realized. The cytotoxicity analysis results also verify the biosafety of the PUF system. In addition, the as‐prepared PUF labels are attached onto the surface of polyethylene material, and human skin, and even have been implanted under chicken skin tissue, promising their practical applications.

Reconfigurable Optical Physical Unclonable Functions Enabled by VO2 Nanocrystal Films

“…The normalized similarity shows results similar to the hamming distance, as shown in Figure 5c. The similarity statistics of 396 nm VO 2 R-PUF speckle patterns were captured at 25,35,45,55,65,68, and 75 °C, compared with each other as shown in Figure 5d. The comparison results show that the speckle pattern captured at 75 °C to other temperatures had a low similarity index, while a high similarity index can be observed between other temperatures, illustrating that the speckle pattern is reconstructed when the VO 2 nanocrystal film thoroughly phase transitions at 75 °C.…”

“…The laser, PUF, and CCD camera were placed at the same height. The speckle pattern signals were captured at 25,35,45,55,65,68, and 75 °C, respectively, during the heating and cooling process. The hamming distance was used to quantify the difference between two binary strings of the same length.…”

“…Up to now, various kinds of PUFs have been proposed and used for anti-counterfeiting and information protection. Traditional PUFs can be divided into electrical PUF − and optical PUF. − Arbiter PUF and ring oscillator PUF are typical electrical PUFs that could integrate with electronic devices well and are widely used. However, the most significant disadvantage of these PUFs is that the attacker could predict the rest of the CRPs by establishing a model after obtaining a part of the CRP, which means that mathematical un-clonability could not be guaranteed.…”

Unclonable Features via Electrospraying of Bulk Polymers

“…A broad range of materials and authentication systems has been studied for PUF applications. Examples include, carbon nanotubes, microlenses, nanogels, , nanoflakes, nanoislands, nanowires, silk, , nanodiamonds, lanthanide-doped zeolites, quantum dots, , and perovskite nanocrystals. − A common characteristic of these studies is that they use different forms of nanoscale and microscale particles. Despite the unique properties and appealing characteristics of these materials, there are practical issues that relate to the cost and scalable manufacturing of such PUFs for industrial applications.…”

Direct laser printing of high-resolution physically unclonable anti-counterfeit labels

“…Optical PUF labels, i.e. labels with a read-out procedure based on detection of various optical signals as reflection, Rayleigh or Raman scattering, luminescence, etc., have been rapidly evolving during last decade [4][5][6][7][8][9][10][11] . Utilization of chemically synthesized nanomaterials possessing characteristic fingerprint-like photoluminescence or Raman scattering signals are widely employed to realize optical PUF labels 9,12 .…”