Hyung Jong Bae

Biomimetic Microfingerprints for Anti‐Counterfeiting Strategies

An unclonable, fingerprint-mimicking anti-counterfeiting strategy is presented that encrypts polymeric particles with randomly generated silica film wrinkles. The generated wrinkle codes are as highly unique as human fingerprints and are technically irreproducible. Superior to previous physical unclonable functions, codes are tunable on demand and generable on various geometries. Reliable authentication of real-world products that have these microfingerprints is demonstrated using optical decoding methods.

Self-organization of maze-like structures via guided wrinkling

A novel self-organization approach for constructing maze-like structures is presented by controlling wrinkling on a microparticle. Sophisticated three-dimensional (3D) structures found in nature are self-organized by bottom-up natural processes. To artificially construct these complex systems, various bottom-up fabrication methods, designed to transform 2D structures into 3D structures, have been developed as alternatives to conventional top-down lithography processes. We present a different self-organization approach, where we construct microstructures with periodic and ordered, but with random architecture, like mazes. For this purpose, we transformed planar surfaces using wrinkling to directly use randomly generated ridges as maze walls. Highly regular maze structures, consisting of several tessellations with customized designs, were fabricated by precisely controlling wrinkling with the ridge-guiding structure, analogous to the creases in origami. The method presented here could have widespread applications in various material systems with multiple length scales.

Hierarchical shape-by-shape assembly of microparticles for micrometer-scale viral delivery of two different genes

Understanding tissue engineering using a bottom-up approach has been hindered by technical limitations because no platform can demonstrate the controlled formation of a heterogeneous population of cells in microscale. Here, we demonstrate hierarchical shape-by-shape assembly of virus-laden particles into larger ones to transfect two different genes on the seeded cells. We show that smaller daughter particles with different sizes and shapes can be assembled into the matching indentations of larger parent particles with different sizes and shapes. Then, we transfected a population of cells with two different gene-transfecting viruses, each of which was laden on the parent or daughter particles.

Wrinkiled microparticles for unclonable microtaggants

This paper presents wrinkled microparticles as unreplicable, unique, yet configurable microtaggants for anti-counterfeiting purposes. We mimicked the shape of the human fingerprint in microscale structures using three-dimensional wrinkle patterning. We utilized irreproducible distributions of ridges on wrinkled microparticles as unique codes, similar to human fingerprints, for identification. These wrinkled microparticles can provide reliable authentication by attaching to authentic products because they can be analyzed by general fingerprint-identification methods, exhibit high individuality, and allow mass production by combining lithography-free patterning with a particle-based substrate.