Gradient-Wrinkled Microparticle with Grayscale Lithography Controlling the Cross-Linking Densities for High Security Level Anti-Counterfeiting Strategies

Abstract

Physical unclonable functions (PUFs) enable different characteristics according to the purpose, such as easy to access identification, high security level, and high code capacity, against counterfeiting a product. However, most multiplex approaches have been implemented by embedding several security features rather than one feature. In this paper, we present a high security level anti-counterfeiting strategy using only labyrinth wrinkle patterns with different complexities, which can be used as unique and unclonable codes. To generate codes with different levels in a microtaggant, we fabricated wrinkle patterns with characteristic wavelength gradients using grayscale lithography. The elastic modulus of the polymer substrate and corresponding wavelength after the wrinkling process were controlled by designing the gray level of each subcode region in a gray-level mask image for photopolymerization of the microparticle substrate. We then verified the uniqueness of the extracted minutia codes through a cross-correlation analysis. Finally, we demonstrated the authentication strategies by decoding different minutia codes according to the scanning resolution during the decoding. Overall, the presented patterning method can be widely used in security code generation.

Recent Advances in Polymer Additive Engineering for Diagnostic and Therapeutic Hydrogels

“…They were also able to create maze-like structures by guided wrinkling [ 179 ] ( Figure 15 c). Additionally, further-improved security of these fingerprints was possible with gray-scale lithography [ 180 ] ( Figure 15 d).…”

“…Copyright 2017 AAAS. ( d ) Demonstration of gradient wrinkling for higher security level anti-counterfeiting; scale bar is 100 μm; adapted with permission by the authors of [ 180 ]. Published under CC-BY-NC-ND license.…”

Anti-Counterfeiting Tags Using Flexible Substrate with Gradient Micropatterning of Silver Nanowires

“…It enables visible patterns only under UV light and is popularly used for passports and currencies. In order to create a complex anti-counterfeiting technology, methods of expressing structural color using nanoparticles or nanostructures, changing the shape of a pattern according to an angle, or changing reflectance and color using a strong magnetic field are being studied [10][11][12][13]. The environmental problems of luminescent materials and economic challenges posed by the difficulty of manufacturing nanoparticles and nanopatterns on a large scale need further improvement and attention.…”

One-step pipetting of barcoded planar microparticles into compact monolayer assembling chip for efficient readout of multiplexed immunoassay

“…Among those, barcoded planar microparticles have many desirable qualities. First is scalability; the potential number of simultaneous measurement (multiplexity) grows proportionally with the number of encodable barcodes which is significantly higher than most nonbarcoded particles or assays [1][2][3][4][5][6] . Second is generality; due to many chemical modifications and particle material available 7 , these particles can be applied to detecting various analytes including oligonucleotides [8][9][10][11][12][13] , proteins [14][15][16][17][18] and cells [19][20][21][22] .…”