For decades, bioinspired functional materials have been attracting the interest of many researchers for their remarkable characteristics. In particular, some plant leaves are well known for their inherent superhydrophobic nature. Salvinia molesta, a free-floating aquatic fern, has egg-beater-shaped hierarchical trichomes on its surface of leaves. Due to the unique structure and complex wettability of the hairs, this plant has the ability to maintain a stable thick air layer upon the structure when it is submerged underwater. Often referred to as the “Salvinia Effect,” this property is expected to be suitable for use in hydrodynamic drag reduction. However, due to the complex shape of the trichome, currently applied fabrication methods are using a three-dimensional printing system, which is not applicable to mass production because of its severely limited productivity. In this work, artificial Salvinia leaf inspired by S. molesta was fabricated using a conventional soft lithography method assisted with capillary-force-induced clustering of micropillar array. The fabrication method suggested in this work proposes a promising strategy for the manufacturing of Salvinia-inspired hydrodynamic drag reduction surfaces.

Polymer shrinkage in nano-imprint lithography (NIL) is one of the critical issues that must be considered in order to produce a quality product. Especially, this condition should be considered during the manufacture of optical elements, because micro/nano-structured optical elements should be controlled to fit the desired shape in order to achieve the intended optical performance. In this paper, during NIL, we characterized the shrinkage of polymeric resin on micro lens array (MLA), which is one of the representative micro/nano-structured optical elements. The curvature shape and optical performance of MLA were measured to check the shrinkage tendency during the process. The master mold of MLA was generated by the two-photon polymerization (2PP) additive manufacturing method, and the tested samples were replicated from the master mold with NIL. Several types of resin were adjusted to prepare the specimens, and the shrinkage effects in each case were compared. The shrinkage showed different trends based on the NIL materials and MLA shapes. These characterizations can be applied to compensate for the MLA design, and the desired performance of MLA products can be achieved with a corrected master mold.

Imprint lithography is one of the most used techniques for fabricating microstructures, owing to its high efficiency in both costs and time. However, imprinting has limited feasibility in realizing complex microstructures due to difficulties arising from the inherent limitations in the demolding process. Herein, a facile method is demonstrated for fabricating closed‐loop reentrant topographies with microscale meshes through a combination of imprint lithography and shape memory polymer (SMP). The mesh structure imprinted onto the pre‐pressed SMP pillar array can be elevated by utilizing the form‐switchable property of SMP to fabricate suspended micromesh. Suspended micromesh is fully supported by restored SMP micropillar array, exhibiting a closed‐loop shape that cannot be achieved with conventional imprint lithographic methods. Also, by the nature of reentrant geometry, liquid‐repellency can be realized even for liquids with a lower surface tension than water, offering numerous applications in self‐cleaning, droplet manipulation, and antifouling. Various liquid‐repellent performances of the fabricated suspended micromesh are investigated and compared to the theoretical expectations for a non‐wetting structure, confirming the successful establishment of reentrant topography in the fabricated structures. The proposed lithographic technique can be broadly utilized not only for liquid‐repellent surfaces but also for the fabrication of various functional structures.

A variety of sensor systems have been developed to monitor the structural health status of buildings and infrastructures. However, most sensor systems for structural health monitoring (SHM) are difficult to use in extreme conditions, such as a fire situation, because of their vulnerability to high temperature and physical shocks, as well as time-consuming installation process. Here, we present a smart ball sensor (SBS) that can be immediately installed on surfaces of structures, stably measure vital SHM data in real time and wirelessly transmit the data in a high-temperature fire situation. The smart ball sensor mainly consists of sensor and data transmission module, heat insulator and adhesive module. With the integrated device configuration, the SBS can be strongly attached to the target surface with maximum adhesion force of 233.7-N and stably detect acceleration and temperature of the structure without damaging the key modules of the systems even at high temperatures of up to 500 °C while ensuring wireless transmission of the data. Field tests for a model pre-engineered building (PEB) structure demonstrate the validity of the smart ball sensor as an instantly deployable, high-temperature SHM system. This SBS can be used for SHM of a wider variety of structures and buildings beyond PEB structures.

Dry adhesives inspired by gecko footpads have garnered considerable attention due to their unique features, including strong yet reversible adhesion, self-cleaning properties, and repeatable use. However, scaling these microstructured adhesives from laboratory fabrication to continuous, high-throughput manufacturing poses significant challenges. In this study, we introduce a stepwise thermal patterning system designed for the scalable production of gecko-inspired dry adhesives on flexible substrates. This automated system combines sequential processes such as plate-to-plate micro-molding, rapid thermal curing, demolding, and roll-up of the patterned film. By raising the curing temperature to approximately 180oC and employing an efficient stepwise imprinting method, we achieve fabrication speeds of up to 150 mm/min without compromising pattern accuracy. The system successfully replicates micropillar structures with a diameter of 15 μm and height of 15 μm, featuring 20 μm mushroom-shaped tips on flexible substrates. The resulting dry adhesives demonstrate stable pull-off strengths of 20-23 N/cm² and retain over 83.5% of their initial adhesion after 100,000 attachment–detachment cycles. These findings highlight the potential of our platform for reliable, high-throughput manufacturing of bio-inspired adhesives, paving the way for various industrial applications such as robotic manipulators, pick-and-place electronic assembly, and wearable devices that require repeated, residue-free attachment.