The boundaries between domains in single-layer graphene strongly influence its electronic properties. However, existing approaches for domain visualization, which are based on microscopy and spectroscopy, are only effective for domains that are less than a few micrometres in size. Here, we report a simple method for the visualization of arbitrarily large graphene domains by imaging the birefringence of a graphene surface covered with nematic liquid crystals. The method relies on a correspondence between the orientation of the liquid crystals and that of the underlying graphene, which we use to determine the boundaries of macroscopic domains.

crystal (LC) fi lm containing an ordered, periodic array of smectic LC defects. [ 9,10 ] Unlike previously reported self-assembling materials, which have been geared toward defect-free systems of the ordered structures, these approaches rely on the order of artifi cially made defects as building blocks to create templates. The proposed approaches based on LC defects have signifi cant advantages over existing methods to micro/nanopatterning applications, including easy fabrication, the creation of long-range surface ordering, very rapid formation of periodic arrays, and the ability to generate various featured sizes ranging from the micrometer to the sub-micrometer scale. Furthermore, the ordered array of LC defects occurs rapidly due to reversible and non-covalent interactions between the LC molecules and can easily be generated by controlling surface anchoring, which is a very simple and costeffective mechanism that is well suited to mass production. In addition, this process should not be limited to specifi c rodlike LC materials and it should be applicable to other smectic LC systems forming similar defect structures. Accordingly, such defect orders of LC materials can be very strong candidates for the periodic templates, compared to other soft-building blocks such as block copolymers, colloids, and surfactants.To introduce this new type of building block based on LC defect order, fi rstly we will describe various types of LC phases and their versatile defect structures. In particular, focal conic domains (FCDs), which are typical defect structures of the smectic phase, will be demonstrated in Section 2, since FCDs were fi rstly used to create defect orders. Next, we deal with defect arrays from three different FCDs including toric FCD (TFCD), parabolic FCD (PFCD), and cylindrical oily streak (OS). The TFCDs, which are generated in an antagonistic surface anchoring condition, will be described in detail. Then, the mechanism of TFCD formation is described in terms of surface anchoring, direct internal structure observation, and energetics in Section 3. In Section 4, the template-assisted self-assembling approaches, including some manipulating methods for the domain size, arrangement, and selective patterning of TFCDs, are demonstrated. Finally, we discuss their applications in soft lithographic templates, superhydrophobic surfaces, microlens arrays, organic photomasks, and trapping templates for colloidal particles based on large-area TFCD-array patterning in Section 5.As the fi eld of information displays is maturing, LC materials research is undergoing a modern-day renaissance. Devices Smectic Liquid Crystal Defects for Self-Assembling of Building Blocks and Their Lithographic ApplicationsRecently, it has been reported that liquid crystal (LC) defects can be used to create highly periodic templates by controlling the surface anchoring and the elastic properties of LC molecules. The self-assembled defect ordering of the LC materials takes advantage of the ability to achieve fast stabilization of molecular orde...

Developing methods to assemble nanomaterials into macroscopic scaffolds is of critical significance at the current stage of nanotechnology. However, the complications of the fabrication methods impede the widespread usages of newly developed materials even with the superior properties in many cases. Here, we demonstrate the feasibility of a highly-efficient and potentially-continuous fiber-spinning method to produce high-performance carbon nanotube (CNT) fiber (CNTF). The processing time is <1 min from synthesis of CNTs to fabrication of highly densified and aligned CNTFs. CNTFs that are fabricated by the developed spinning method are ultra-lightweight, strong (specific tensile strength = 4.08 ± 0.25 Ntex −1 ), stiff (specific tensile modulus = 187.5 ± 7.4 Ntex −1 ), electrically conductive (2,270 S m 2 kg −1 ), and highly flexible (knot efficiency = 48 ± 15%), so they are suitable for various high-value fabric-based applications.

Humidity sensors are essential components in wearable electronics for monitoring of environmental condition and physical state. In this work, a unique humidity sensing layer composed of nitrogen-doped reduced graphene oxide (nRGO) fiber on colorless polyimide film is proposed. Ultralong graphene oxide (GO) fibers are synthesized by solution assembly of large GO sheets assisted by lyotropic liquid crystal behavior. Chemical modification by nitrogen-doping is carried out under thermal annealing in H (4%)/N (96%) ambient to obtain highly conductive nRGO fiber. Very small (≈2 nm) Pt nanoparticles are tightly anchored on the surface of the nRGO fiber as water dissociation catalysts by an optical sintering process. As a result, nRGO fiber can effectively detect wide humidity levels in the range of 6.1-66.4% relative humidity (RH). Furthermore, a 1.36-fold higher sensitivity (4.51%) at 66.4% RH is achieved using a Pt functionalized nRGO fiber (i.e., Pt-nRGO fiber) compared with the sensitivity (3.53% at 66.4% RH) of pure nRGO fiber. Real-time and portable humidity sensing characteristics are successfully demonstrated toward exhaled breath using Pt-nRGO fiber integrated on a portable sensing module. The Pt-nRGO fiber with high sensitivity and wide range of humidity detection levels offers a new sensing platform for wearable humidity sensors.

Weavable sensing fibers with superior mechanical strength and sensing functionality are crucial for the realization of wearable textile sensors. However, in the fabrication of previously reported wearable sensing fibers, additional processes such as reduction, doping, and coating were essential to satisfy both requirements. The sensing fibers should be continuously synthesized in a scalable process for commercial applications with high reliability and productivity, which was challenging. In this study, we first synthesize mass-producible wearable sensing fibers with good mechanical properties and sensing functionality without additional processes by incorporating carbon nanotubes (CNTs) into distinct nanocellulose. Nanocellulose extracted from tunicate (TCNF) is homogeneously composited with single-walled CNTs, and composite fibers (TCNF/CNT) are continuously produced in aligned directions by wet spinning, facilitating liquid-crystal properties. The TCNF/CNT fibers exhibit a superior gas (NO 2 )-sensing performance with high selectivity and sensitivity (parts-per-billion detection). In addition, the TCNF/CNT fibers can endure complex and harsh distortions maintaining their intrinsic sensing properties and can be perfectly integrated with conventional fabrics using a direct weaving process. Our meter-scale scalable synthesis of functional composite fibers is expected to provide a mass production platform of versatile wearable sensors.