Functional 1D metal oxides have attracted much attention because of their unique applications in electronic, optoelectronic, and spintronic devices.[1] For semiconducting oxide nanowires (NWs) (e.g., ZnO, In 2 O 3 , and SnO 2 NWs), field-effect transistors and light-emitting diodes have been demonstrated. [2] Metallic oxide nanoscale materials, such as nanoscale RuO 2 , can be good candidates as interconnects in electronic applications.[3] RuO 2 nanomaterials have been produced by chemical vapor deposition (CVD) and through chemical reaction. [3b,4] Recently, RuO 2 NWs have been synthesized using pure Ru as metal target under different flux ratios of O 2 /Ar in a reactive sputtering system.[5]For core/shell structures, extensive research has been carried out on systems such as Ge/Si, [6] GaN/AlN/AlGaN, [7] Ta 2 O 5 /SiO 2 , [8] and Fe 3 O 4 /MgO. [9] The Ge/Si core/shell NW, for example, is a high-performance field-effect transistor because of the reduced carrier scattering. GaN/AlN/AlGaN core/shell NWs exhibit a high electron mobility. For the SiO 2 / Ta 2 O 5 core/shell structure, the axial confinement of light propagation can effectively reduce the energy loss owing to the difference in refractive index between Ta 2 O 5 and SiO 2 . Following the successful synthesis of a RuO 2 /TiO 2 core/ shell structure by reactive sputtering, [10] we mainly focus on the investigation of the physical properties of the RuO 2 NWs in the present study. The detailed epitaxial relationship and electronic structures of the RuO 2 /TiO 2 core/shell structure synthesized by reactive sputtering are investigated. The mechanical, optical, and electrical properties and photocatalyst response to UV irradiation are characterized. Our results suggest the potential application of the NWs as interconnects and optoelectronic devices. Figure 1a shows a scanning electron microscopy (SEM) image of RuO 2 NWs synthesized by the reactive sputtering approach at a synthesis temperature of 450°C for 3 h, and indicates a high density of uniform RuO 2 NWs more than several micrometers long. In addition, most of the RuO 2 NWs have a square cross section, as shown in the inset of Figure 1a. The corresponding X-ray diffraction (XRD) spectrum, shown in Figure 1b, confirms that the phase of the NWs is rutile-structured RuO 2 with lattice-constant values of a = 0.45 nm and c = 0.31 nm. After deposition of a thin TiO 2 layer via reactive sputtering deposition, the morphology of these NWs remains unchanged, but the sizes increase, as shown in Figure 1c. The corresponding XRD spectrum of the NWs is shown in Figure

Fiber‐shaped sensors are useful for the simple fabrication of textile‐based electronics, which have excellent wearability and conformal adaptability for ubiquitous healthcare systems. In the case of temperature monitoring using highly deformable textronics for diagnostics, the device operation can be hindered by strain‐induced interferences when various movements are performed. An intrinsic strain‐insensitive fiber‐type temperature sensor with compressed micro‐wrinkles is demonstrated. The fiber sensor exhibits remarkable sensitivity (≈0.93% °C‐1) and high strain insensitivity until 60% tensile strain. Once the sensor is regularly knitted into a soft fabric, negligible changes in the electrical resistance are observed up to 180% tensile strain. Temperature‐responsive wavy architectures on the fiber surface are fabricated via a facile dip‐coating method after applying a pre‐strain, followed by lamination of an elastic protective layer. By fabricating uniform microscale wavy architectures and adjusting the wavelength of the micro‐wrinkles, the device performance is significantly improved. The fiber temperature sensor demonstrated is highly repeatable and reproducible for <1000 cycles, exhibiting excellent cyclic responses to on/off switching. Additionally, the fiber sensor can be integrated into a smart glove with a wireless transmitter to monitor continuous changes of the outside temperature without deformation‐induced interference under numerous dynamic gestures and movements.

Integrated bioelectronics with conformal adhesion interfaces on dry/wet biosurfaces and water‐repellent stretchable electric elements are in high demand for reliable real‐time diagnostics of the dynamic human body. Here, the authors present a diving beetle‐inspired electro‐adhesive patch with mechanically robust nanowire‐implanted conductive multiscale architectures that provides a skin‐adaptable, isotropically stretchable interface for a multiple‐biosignal monitoring device. Using a facile all‐solution‐based process, a hydrophobic, stretchable carbon‐nanotube‐implanted conductive composite electrode on insect‐like adhesive architectures is fabricated. The conductive adhesive patch with bioinspired wrinkled microsuction cups exhibits remarkable enhanced wet adhesion with sweat‐drainability, as well as high stretchable electrical performance under tensile strain in dry and wet conditions. Owing to the high durability and softness of the bioinspired electric adhesive patch, its performance is successfully maintained even with repeated attachment (<1000 cycles) and mechanical stretching. To demonstrate a multiplexed wearable device, a temperature‐sensitive conductive material is coated onto the isotropically strain‐insensitive stretchable electrode to allow simultaneous electrocardiogram and temperature measurements on soft skin in dry and wet environments.

Recent advances in bioinspired nano/microstructures have received attention as promising approaches with which to implement smart skin-interfacial devices for personalized health care. In situ skin diagnosis requires adaptable skin adherence and rapid capture of clinical biofluids. Here, we report a simple, all-in-one device consisting of microplungers and hydrogels that can rapidly capture biofluids and conformally attach to skin for stable, real-time monitoring of health. Inspired by the male diving beetle, the microplungers achieve repeatable, enhanced, and multidirectional adhesion to human skin in dry/wet environments, revealing the role of the cavities in these architectures. The hydrogels within the microplungers instantaneously absorb liquids from the epidermis for enhanced adhesiveness and reversibly change color for visual indication of skin pH levels. To realize advanced biomedical technologies for the diagnosis and treatment of skin, our suction-mediated device is integrated with a machine learning framework for accurate and automated colorimetric analysis of pH levels.

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