High-Uniformity, Shape-Controlled Silicon Nanowires for Enhanced Performance in Optoelectronic Devices.

Silicon nanowires (Si NWs) have attracted considerable interest owing to their distinctive properties, which render them promising candidates for a wide range of advanced applications in electronics, photonics, energy storage, and sensing. However, challenges in achieving large-scale production, high uniformity, and shape control limit their practical use. This study presents a novel fabrication approach combining nanoimprint lithography, nanotransfer printing, and metal-assisted chemical etching to produce highly uniform and shape-controlled Si NW arrays.

Flexible All-Inorganic Thermoelectric Yarns.

Achieving both formability and functionality in thermoelectric materials remains a significant challenge due to their inherent brittleness. Previous approaches, such as polymer infiltration, often compromise thermoelectric efficiency, underscoring the need for flexible, all-inorganic alternatives. This study demonstrates that the extreme brittleness of thermoelectric bismuth telluride (BiTe) bulk compounds can be overcome by harnessing the nanoscale flexibility of BiTe nanoribbons and twisting them into a yarn structure.

Metasurface-Embedded Contact Lenses for Holographic Light Projection.

Contact lenses have been instrumental in vision correction and are expected to be utilized in augmented reality (AR) displays through the integration of electronic and optical components. In optics, metasurfaces, an array of sub-wavelength nanostructures, have offered optical multifunctionality in an ultra-compact form factor, facilitating integration into various imaging, and display systems. However, transferring metasurfaces onto contact lenses remains challenging due to the non-biocompatible materials of extant imprinting methods and the structural instability caused by the swelling and shrinking of the wetted surface.

Nanostructure engineering in organic semiconductor devices toward interface matching.

The performance of organic semiconductor devices with heterojunctions between the organic semiconductors and electrodes can be improved by reducing the contact resistance. In this study, we have developed nanopatterned electrodes that gradually change the impedance at the interface between the metal and organic semiconductor in organic devices, which were fabricated in periodic patterns using nanoimprint lithography. The imprint pattern spacing was changed to control the interface between the metal and organic semiconductor to ensure smooth carrier injection.

Nanoribbon Yarn with Versatile Inorganic Materials.

Nanomaterial-based yarns have been actively developed owing to their advantageous features, namely, high surface-area-to-volume ratios, flexibility, and unusual material characteristics such as anisotropy in electrical/thermal conductivity. The superior properties of the nanomaterials can be directly imparted and scaled-up to macro-sized structures. However, most nanomaterial-based yarns have thus far, been fabricated with only organic materials such as polymers, graphene, and carbon nanotubes.

Density-controlled electrochemical synthesis of ZnO nanowire arrays using nanotextured cathode.

Zinc oxide (ZnO) nanowires fabricated via wet chemical synthesis on flexible polymer substrates are inherently unstable against mechanical bending stress because of their high density and weak adhesion to the substrate. We introduce a novel method for controlling the density of such ZnO nanowire arrays using a three-dimensional corrugated metal substrate. These metal substrates, featuring extruded and recessed patterns fabricated via nanoimprint lithography, were employed as cathodes during the electrochemical deposition of ZnO nanowire arrays.

Illuminating Recent Progress in Nanotransfer Printing: Core Principles, Emerging Applications, and Future Perspectives.

As the demand for diverse nanostructures in physical/chemical devices continues to rise, the development of nanotransfer printing (nTP) technology is receiving significant attention due to its exceptional throughput and ease of use. Over the past decade, researchers have attempted to enhance the diversity of materials and substrates used in transfer processes as well as to improve the resolution, reliability, and scalability of nTP. Recent research on nTP has made continuous progress, particularly using the control of the interfacial adhesion force between the donor mold, target material, and receiver substrate, and numerous practical nTP methods with niche applications have been demonstrated.

Correction: A wearable colorimetric sweat pH sensor-based smart textile for health state diagnosis.

Correction for 'A wearable colorimetric sweat pH sensor-based smart textile for health state diagnosis' by Ji-Hwan Ha , , 2023, , 4163-4171, https://doi.org/10.1039/d3mh00340j.

Recent Advances in Sensor-Actuator Hybrid Soft Systems: Core Advantages, Intelligent Applications, and Future Perspectives.

The growing demand for soft intelligent systems, which have the potential to be used in a variety of fields such as wearable technology and human-robot interaction systems, has spurred the development of advanced soft transducers. Among soft systems, sensor-actuator hybrid systems are considered the most promising due to their effective and efficient performance, resulting from the synergistic and complementary interaction between their sensor and actuator components. Recent research on integrated sensor and actuator systems has resulted in a range of conceptual and practical soft systems.

A wearable colorimetric sweat pH sensor-based smart textile for health state diagnosis.

Sweat pH is an important indicator for diagnosing disease states, such as cystic fibrosis. However, conventional pH sensors are composed of large brittle mechanical parts and need additional instruments to read signals. These pH sensors have limitations for practical wearable applications.

Micro-/Nanohierarchical Structures Physically Engineered on Surfaces: Analysis and Perspective.

The high demand for micro-/nanohierarchical structures as components of functional substrates, bioinspired devices, energy-related electronics, and chemical/physical transducers has inspired their in-depth studies and active development of the related fabrication techniques. In particular, significant progress has been achieved in hierarchical structures physically engineered on surfaces, which offer the advantages of wide-range material compatibility, design diversity, and mechanical stability, and numerous unique structures with important niche applications have been developed. This review categorizes the basic components of hierarchical structures physically engineered on surfaces according to function/shape and comprehensively summarizes the related advances, focusing on the fabrication strategies, ways of combining basic components, potential applications, and future research directions.

Water-resistant free-standing DNA-complexed films with antioxidant and HO-responsive activity.

Water-insoluble DNA complexes are suitable for producing free-standing DNA films due to their low water sensitivity, which prevents their rapid degradation in aqueous environments. Here, we proposed two types of free-standing films that exhibit low dissolution rates in water: low molecular weight chitosan (LCS)-DNA films and phosphatidylcholine (PC)-cetyltrimethylammonium (CTMA)-DNA films. The structure and binding characteristics of the LCS-DNA and PC-CTMA-DNA complexes were investigated with UV-Vis spectroscopy and the fluorescent characteristics of daunorubicin bound to them.

Nanotransfer-on-Things: From Rigid to Stretchable Nanophotonic Devices.

The growing demand for nanophotonic devices has driven the advancement of nanotransfer printing (nTP) technology. Currently, the scope of nTP is limited to certain materials and substrates owing to the temperature, pressure, and chemical bonding requirements. In this study, we developed a universal nTP technique utilizing covalent bonding-based adhesives to improve the adhesion between the target material and substrate.

Nanoscale three-dimensional fabrication based on mechanically guided assembly.

The growing demand for complex three-dimensional (3D) micro-/nanostructures has inspired the development of the corresponding manufacturing techniques. Among these techniques, 3D fabrication based on mechanically guided assembly offers the advantages of broad material compatibility, high designability, and structural reversibility under strain but is not applicable for nanoscale device printing because of the bottleneck at nanofabrication and design technique. Herein, a configuration-designable nanoscale 3D fabrication is suggested through a robust nanotransfer methodology and design of substrate's mechanical characteristics.

Multidimensional Honeycomb-like DNA Nanostructures Made of C-Motifs.

Thanks to its remarkable properties of self-assembly and molecular recognition, DNA can be used in the construction of various dimensional nanostructures to serve as templates for decorating nanomaterials with nanometer-scale precision. Accordingly, this study discusses a design strategy for fabricating such multidimensional DNA nanostructures made of simple C-motifs. One-dimensional (1D) honeycomb-like tubes (1HTs) and two-dimensional (2D) honeycomb-like lattices (2HLs) were constructed using a C-motif with an arm length of 14 nucleotides (nt) at an angle of 240° along the counterclockwise direction.

Functional Asymmetry-Enabled Self-Adhesive Film via Phase Separation of Binary Polymer Mixtures for Soft Bio-Integrated Electronics.

Biocompatible adhesive films are important for many applications (e.g., wearable devices, implantable devices, and attachable sensors).

Nanomaterial-Embedded DNA Films on 2D Frames.

Recently, 3D printing has provided opportunities for designing complex structures with ease. These printed structures can serve as molds for complex materials such as DNA and cetyltrimethylammonium chloride (CTMA)-modified DNA that have easily tunable functionalities via the embedding of various nanomaterials such as ions, nanoparticles, fluorophores, and proteins. Herein, we develop a simple and efficient method for constructing DNA flat and curved films containing water-soluble/thermochromatic dyes and di/trivalent ions and CTMA-modified DNA films embedded with organic light-emitting molecules (OLEM) with the aid of 2D/3D frames made by a 3D printer.

Spherical Micro/Nano Hierarchical Structures for Energy and Water Harvesting Devices.

Three-dimensional (3D) hierarchical structures have been explored for various applications owing to the synergistic effects of micro- and nanostructures. However, the development of spherical micro/nano hierarchical structures (S-HSs), which can be used as energy/water harvesting systems and sensing devices, remains challenging owing to the trade-off between structural complexity and fabrication difficulty. This paper presents a new strategy for facile, scalable S-HS fabrication using a thermal expansion of microspheres and nanopatterned structures.

Wafer-scale, highly uniform, and well-arrayed suspended nanostructures for enhancing the performance of electronic devices.

Suspended nanostructures play an important role in enhancing the performance of a diverse group of nanodevices. However, realizing a good arrangement and suspension for nanostructures of various shapes remains a significant challenge. Herein, a rapid and simple method for fabricating wafer-scale, highly uniform, well-arrayed suspended nanostructures nanowelding lithography is reported.

Direct Chemisorption-Assisted Nanotransfer Printing with Wafer-Scale Uniformity and Controllability.

Nanotransfer printing techniques have attracted significant attention due to their outstanding simplicity, cost-effectiveness, and high throughput. However, conventional methods a chemical medium hamper the efficient fabrication with large-area uniformity and rapid development of electronic and photonic devices. Herein, we report a direct chemisorption-assisted nanotransfer printing technique based on the nanoscale lower melting effect, which is an enabling technology for two- or three-dimensional nanostructures with feature sizes ranging from tens of nanometers up to a 6 in.

Demonstration of elementary functions DNA algorithmic self-assembly.

Target-oriented cellular automata with computation are the primary challenge in the field of DNA algorithmic self-assembly in connection with specific rules. We investigate the feasibility of using the principle of cellular automata for mathematical subjects by using specific logic gates that can be implemented into DNA building blocks. Here, we connect the following five representative elementary functions: (i) enumeration of multiples of 2, 3, and 4 (demonstrated R094, R062, and R190 in 3-input/1-output logic rules); (ii) the remainder of 0 and 1 (R132); (iii) powers of 2 (R129); (iv) ceiling function for /2 and /4 (R152 and R144); and (v) analogous pattern of annihilation (R184) to DNA algorithmic patterns formed by specific rules.

Biocompatible All-in-One Adhesive Needle-Free Cup Patch for Enhancing Transdermal Drug Delivery.

Patch-type drug delivery has garnered increased attention as an attractive alternative to the existing drug delivery techniques. Thus far, needle phobia and efficient drug delivery remain huge challenges. To address the issue of needle phobia and enhance drug delivery, we developed a needle-free and self-adhesive microcup patch that can be loaded with an ultrathin salmon DNA (SDNA) drug carrier film.

Biocompatible Nanotransfer Printing Based on Water Bridge Formation in Hyaluronic Acid and Its Application to Smart Contact Lenses.

Many conventional micropatterning and nanopatterning techniques employ toxic chemicals, rendering them nonbiocompatible and unsuited for biodevice production. Herein the formation of water bridges on the surface of hyaluronic acid (HA) films is exploited to develop a transfer-based nanopatterning method applicable to diverse structures and materials. The HA film surface, made deformable via water bridge generation, is brought into contact with a functional material and subjected to thermal treatment, which results in film shrinkage, allowing a robust pattern transfer.

Enhancement of refractive index sensing for an infrared plasmonic metamaterial absorber with a nanogap.

An infrared plasmonic metamaterial absorber with a nanogap was numerically and experimentally investigated as a refractive index sensor. We experimentally demonstrated large enhancements of both sensitivity (approximately 1091 nm/refractive index unit) and figure of merit (FOM*; approximately 273) owing to the nanogap formation in the metamaterial absorber to achieve perfect absorption (99%). The refractive index sensing platform was fabricated by producible nanoimprint lithography and isotropic dry etching processes to have a large area and low cost while providing a practical solution for high-performance plasmonic biosensors.

Ultra-Wide Range Pressure Sensor Based on a Microstructured Conductive Nanocomposite for Wearable Workout Monitoring.

Conventional flexible pressure sensors are not suitable for high-pressure applications due to their low saturation pressure. In this study, an ultra-wide range pressure sensor is designed based on the optimized microstructure of the polyimide/carbon nanotubes (PI/CNT) nanocomposite film. The sensing range of the pressure sensor is expanded by adopting polyimide (PI) with a high elastic modulus as a matrix material and its sensitivity is improved through functional sensing film with tip-flattened microdome arrays.