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Wetting behaviors on stretchable supports are very common in our daily lives, however, received limited attention even they show promising potentials in flexible electronics and other fields. In this study, stretchable wetting behaviors of conductive liquids deposited onto two horizontal rubber fibers are investigated. A firm liquid/solid interaction during the stretching process can contribute to a stable liquid bridge between the fibers even under extremely stretching, showing their proof-to-principle ability to monitor human movement toward early diagnosis of Parkinson's disease or sports injury prevention usc Refereed/Peer-reviewed

Extremely straight and laterally aligned cylindrical microdomains of block copolymer (BCP) films have been prepared by simply covering the BCP films with a top coat and dewetting the latter via thermal annealing to generate shear flow in the BCP underlayer. The polystyrene-block-polydimethylsiloxane microdomains are perfectly aligned with sunburst direction along the polyvinyl alcohol top-coat dewetting front from the nucleation point to the end of the dewetting front. This alignment is at least 150 μm long and the aspect ratio is higher than 15 000:1. Studying the morphologies obtained as a function of top-coat and BCP film thickness at various annealing temperatures, highly ordered BCP patterns are obtained for a wide range of shear rates, while higher (but not the highest) temperatures and thicker BCP films lead to more ordered microdomain patterns, because of increased polymer mobility and a reduced surface/interface effect. An imprinting process is also introduced to pattern top coats, which then provide selective control of the dewetting direction so that unidirectionally aligned BCP patterns can be created in specific areas.

Effective temperature measurements are of signifi cance for a fundamental understanding of nanosystems and functional applications, requiring ultimate miniaturization of thermometers with reduced size but maintained sensitivity, simplicity, and accuracy of temperature reading. Grand challenges exist for scenarios of thermal shock or combustion where materials may be subjected to extreme thermal fl ux and drastic temperature variations, and dynamic thermal sensors with an ultrafast response are yet to be developed. Here, an innovative design of silica–gold core–shell (SiO 2 @Au) nanospheres is demonstrated as a potential dynamic sensor with a sub-second response time and accurate temperature determination based on the strong temperature dependence of the thermally induced morphological self-reorganization and characteristic surface plasmon (SP) absorption of the metal shell. The irreversible thermally induced morphological and optical signatures behave as characteristic “fi ngerprints” for temperature recordings, allowing the retrieval of thermal history ex-situ. As compared with current nanothermometer technologies such as metal-fi lled nanotubes, the core–shell nanospherebased dynamic thermosensor offers synergistic advantages of ultrafast time response, fast readout, permanent recording of thermal history, and ex-situ capabilities for effective temperature measurements.

Close-packed arrays of Au nanoparticles are produced in patterned regions by electron beam (e-beam) lithography using a highly sensitive direct–write resist, N + AuCl 4 - (C 8 H 17 ) 4 Br. While the e–beam causes dewetting of the resist to nucleate Au nanoparticles, the following step of thermolysis aids particle growth and removal of the organic part. Thus formed arrays contain Au nanoparticles. Such arrays are patterned into ≈10 μm wide stripes between Au contact pads on SiO 2 /Si substrates to realize electrical rectification. Under forward bias, the device exhibits a threshold voltage of +4.3 V and a high current rectification ratio of 3 × 10 5 , which are stable over many repetitive measurements. The threshold voltage of the rectifier can be reduced by applying an electric stress or by varying the electron dosage used for array formation. The nanoparticle rectifier element could be transferred onto flexible substrates such as PDMS, where the nanoparticle coupling is influenced by swelling of the substrate. Obviously, the nanoparticle size, shape, and the spacing in array are all important for the rectifier device performance. Based on the electrical measurements the mechanism of rectification is found to be due to switching of electrical conduction with applied bias, from short–distance tunneling to F–N type tunneling followed by transient filament formation.

The phase-separation characteristics of spin-cast difluorinated-triethylsilylethynyl anthradithiophene (F-TESADT)/poly(methyl methacrylate) (PMMA) blends are investigated with the aim of fabricating transistors with a high field-effect mobility and stability. It is found that the presence of PMMA in the F-TESADT/PMMA blends prevents dewetting of F-TESADT from the substrate and provides a platform for F-TESADT molecules to segregate and crystallize at the air–film interface. By controlling the solvent evaporation rate of the spin-cast blend solution, it is possible to regulate the phase separation of the two components, which in turn determines the structural development of the F-TESADT crystals on PMMA. At a low solvent evaporation rate, a bilayer structure consisting of highly ordered F-TESAT crystals on the top and low-trap PMMA dielectric on the bottom can be fabricated by a one-step spin-casting process. The use of F-TESADT/PMMA blend films in bottom gate transistors produces much higher field-effect mobilities and greater stability than homo F-TESADT films because the phase-separated interface provides an efficient pathway for charge transport.

Classical microcontact printing involves transfer of molecules adsorbed on the outer surfaces of solid stamps to substrates to be patterned. We prepared spongy mesoporous silica stamps that can be soaked with ink and that were topographically patterned with arrays of submicron contact elements. Multiple successive stamping steps can be carried out under ambient conditions without ink refilling. Lattices of fullerene nanoparticles with diameters in the 100 nm range were obtained by stamping C60/toluene solutions on perfluorinated glass slides partially wetted by toluene. Stamping an ethanolic 1-dodecanethiol solution onto gold-coated glass slides yielded arrays of submicron dots of adsorbed 1-dodecantethiol molecules, even though macroscopic ethanol drops spread on gold. This outcome may be related to the pressure drop across the concave ink menisci at the mesopore openings on the stamp surface counteracting the van der Waals forces between ink and gold surface and/or to reduced wettability of the 1-dodecanethiol dots themselves by ethanol. The chemical surface heterogeneity of gold-coated glass slides functionalized with submicron 1-dodecanethiol dots was evidenced by dewetting of molten polystyrene films eventually yielding ordered arrays of polystyrene nanoparticles

A novel method of creating planar aligned columnar discotic liquid crystals (cDLCs) on surfaces, which also gives control over the azimuthal angle, is presented. Surfaces are chemically patterned with stripes via microcontact printing of organothiol self-assembled monolayers (SAMs) on gold, or via deep UV patterning of organosilane SAMs on silicon. These are then used to isolate long droplets of cDLCs by dewetting in the isotropic phase. Upon cooling from the isotropic into the hexagonal columnar phase, polarizing microscopy reveals that the cDLC aligns in a planar orientation. Results for three triphenylene derivatives (HAT-6, HHTT, H7T) and for a phthalocyanine derivative (8H2Pc) are presented. H7T and HAT-6 are found to align with the director perpendicular to the stripe direction, but HHTT and 8H2Pc align parallel to the stripe direction. This relatively simple new method for creating planar aligned columnar phases of DLCs gives control over the azimuthal angle: a condition required for organic field-effect transistor applications of cDLCs.

A thick film of patterned heterogeneous surface is introduced, in which the surface heterogeneity arises due to a difference in the characteristics of interfacial potential. When a liquid film is coated onto such a surface, the film is unstable only on certain parts of the surface and, consequently, dewetting takes place. In the other parts, the film is stable and no dewetting takes place. This heterogeneous surface is utilized for patterning low-duty-ratio patterns, which has proved challenging for any mold-based unconventional lithographies. Only the natural forces associated with capillarity and dewetting are responsible for the patterning. As a result, defect-free and uniform patterning is possible over a large area.

Regular polymer patterns are formed from casting a dilute polymer solution on a solid substrate. Dissipative structures, e.g., convection patterns, fingering instabilities, and so on, are formed in the evaporation process of casting polymer films. Controlled production and manufacturing of patterned polymer films can be achieved when the evaporating solution edge, especially the meniscus region on the casting substrate, is formed under controlled casting conditions. In this report, we describe a computer-controlled apparatus which has two precisely manipulated sliding glass plates. A narrow, thin liquid film of polymer solution with a receding meniscus is continuously supplied from a small gap between two glass plates (one sliding and the other stationary), and a patterned polymer film is subsequently formed on the stationary substrate from the evaporating solution edge. Several types of polymer patterns from various polymers are reproducibly prepared by changing preparation conditions such as sliding speed and polymer concentration.

Colloidal aggregates with well-controlled sizes, shapes, and structures have been fabricated by dewetting aqueous dispersions of monodispersed spherical colloids across surfaces patterned with two-dimensional arrays of relief structures (or templates). The capability and feasibility of this approach have been demonstrated with the organization of polymer latex or silica beads into homo-aggregates, including circular rings; polygonal and polyhedral clusters; and linear, zigzag, and spiral chains. It was also possible to generate hetero-aggregates in the configuration of HF and H2O molecules that contained spherical colloids of different sizes, compositions, densities, functions, or a combination of these features. These uniform, well-defined aggregates of spherical colloids are ideal model systems to investigate the aerodynamic, hydrodynamic, and optical properties of colloidal particles characterized by non-spherical shapes and/or complex topologies. They can also serve as a new class of building blocks to generate hierarchically self-assembled structures that are expected to exhibit interesting features valuable to areas ranging from condensed matter physics to photonics.

This article gives an overview on a new lithographic technique called capillary force lithography for large-area patterning. The technique simply involves placing a polydimethylsiloxane mold on a polymer film, which is then heated above the glass-transition temperature of the polymer. Various useful microstructures can be obtained by sequential applications of the technique through self-organization. Dewetting, which can be observed in capillary force lithography for relatively thin films, is also described as a new pathway for realizing anisotropic dewetting.

Large-scale patterning of high-quality organic semiconductors is crucial for the fabrication of optoelectronic devices with high efficiency and low cost. Yet, owing to the uncontrollable dewetting dynamics of organic liquid in conventional solution patterning techniques, large defect density of organic architectures is inevitable, which is detrimental to the device performance. To address this challenge, herein a capillary-bridge-mediated assembly technique is developed for regulating the dewetting process, yielding large-scale 1D microstructure ordered arrays. The 1D arrays organic photodetectors exhibit a high optoelectronic performance of light on/off ratio exceeding 100, responsivity of 3.24 A W−1, detectivity of 3.20 × 1011 Jones and fast response speed, showing a great improvement compared with spin-coated membrane devices. In addition, the significant enhancement of the device photodetection under the electronic field modulation is investigated by applying a back-gate voltage and explained with the photocurrent predominating in the OFF state and the neglected thermocurrent and tunneling current promoting in the ON state of the phototransistor devices. The research offers a new insight for the facile fabrication of large-scale integrated photodetectors and other organic devices based on patterned conjugated polymers.

Agglomerated Pt thin films have been proposed as electrodes for electrochemical devices like micro-solid oxide fuel cells (μ-SOFCs) operating at low temperatures. However, comprehensive studies elucidating the interplay between agglomeration state and electrochemical properties are lacking. In this contribution the electrochemical performance of agglomerated and “dense” Pt thin film electrodes on yttria-stabilized-zirconia (YSZ) is correlated with their microstructural characteristics. Besides the microscopically measurable triple-phase-boundary (tpb) where Pt, YSZ and air are in contact, a considerable contribution of “nanoscopic” tpbs to the electrode conductivity resulting from oxygen permeable grain boundaries is identified. It is demonstrated that “dense” Pt thin films are excellent electrodes provided their grain size and thickness are in the nanometer range. The results disprove the prevailing idea that the performance of Pt thin film electrodes results from microscopic and geometrically measurable tpbs only.