Polymorphing Hydrogels Regulated by Photo-reactive DNA Cross-links.

Polymorphing hydrogels can morph into another structure on demand with reprogrammable features. This concept extends the degree of morphing beyond that of traditional shape-morphing hydrogels, which predetermine their morphing capabilities at the fabrication stage. However, current polymorphing hydrogels face limitations due to the need for complex, non-sustained responsiveness or additional chemical steps for reconfigurable morphing.

Time-traceable micro-taggants for anti-counterfeiting and secure distribution of food and medicines.

This study presents an innovative solution for the enhanced tracking and security of pharmaceuticals through the development of microstructures incorporating environmentally responsive, coded microparticles. Utilizing maskless photolithography, we engineered these microparticles with a degradable masking layer with 30 m thickness that undergoes controlled dissolution. Quantitative analysis revealed that the protective layer's degradation, monitored by red fluorescence intensity, diminishes predictably over 144 h in phosphate-buffered saline under physiological conditions.

Optimizing Binding Site Spacing in Fluidic Self-Assembly for Enhanced Microchip Integration Density.

This manuscript presents a comprehensive study on the assembly of microchips using fluidic self-assembly (FSA) technology, with a focus on optimizing the spacing between binding sites to improve yield and assembly. Through a series of experiments, we explored the assembly of microchips on substrates with varying binding site spacings, revealing the impact of spacing on the rate of undesired chip assembly across multiple sites. Our findings indicate a significant reduction in incorrect assembly rates as the spacing increases beyond a critical threshold of 140 μm.

Fluidic self-assembly for MicroLED displays by controlled viscosity.

Displays in which arrays of microscopic 'particles', or chiplets, of inorganic light-emitting diodes (LEDs) constitute the pixels, termed MicroLED displays, have received considerable attention because they can potentially outperform commercially available displays based on organic LEDs in terms of power consumption, colour saturation, brightness and stability and without image burn-in issues. To manufacture these displays, LED chiplets must be epitaxially grown on separate wafers for maximum device performance and then transferred onto the display substrate. Given that the number of LEDs needed for transfer is tremendous-for example, more than 24 million chiplets smaller than 100 μm are required for a 50-inch, ultra-high-definition display-a technique capable of assembling tens of millions of individual LEDs at low cost and high throughput is needed to commercialize MicroLED displays.

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

Anti-counterfeiting technologies for small products are being developed. We present an anti-counterfeiting tag, a grayscale pattern of silver nanowires (AgNWs) on a flexible substrate. The anti-counterfeiting tag that is observable with a thermal imaging camera was fabricated using the characteristics of silver nanowires with high visible light transmittance and high infrared emissivity.

Photopatterned microswimmers with programmable motion without external stimuli.

We introduce highly programmable microscale swimmers driven by the Marangoni effect (Marangoni microswimmers) that can self-propel on the surface of water. Previous studies on Marangoni swimmers have shown the advantage of self-propulsion without external energy source or mechanical systems, by taking advantage of direct conversion from power source materials to mechanical energy. However, current developments on Marangoni microswimmers have limitations in their fabrication, thereby hindering their programmability and precise mass production.

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

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.

Shear Stress-Triggered Deformation of Microparticles in a Tapered Microchannel.

We demonstrate that it is possible to produce microparticles with high deformability while maintaining a high effective volume. For significant particle deformation, a particle must have a void region. The void fraction of the particle allows its deformation under shear stress.

Self-organization of maze-like structures via guided wrinkling.

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.

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.