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  • Platinum diselenide (PtSe2) is a newly discovered Group-10 transition metal dichalcogenide (TMD) which has unique electronic properties, in particular a semimetal-to-semiconductor transition. In this work, we have demonstrated the proposed vertically standing layered structure PtSe2 nanofilms based on hybrid heterojunction with high overall performance was realized for broadband light photodetection ranging from 200 nm to 1550 nm. The high-performance broadband photodetector will open up a new pathway for the development of next-generation two dimensional Group-10 materials based optoelectronic devices.

    • Longhui Zeng
    • Shenghuang Lin
    • Yuen Hong Tsang
    Article Open Access
  • The scattering of charge carriers with line defects, i.e., threading dislocations, needs to be decreased to further enhance electron mobility of lattice-mismatched epitaxial films and heterostructures for the application of high-performance electronic devices. Here, we report a strategy to post-treat epitaxial La-doped BaSnO3 films by delicately controlling oxygen partial pressure p(O2), which achieved significant increase in room temperature electron mobility to 122 cm2∙V−1∙s−1. This mobility enhancement is attributed to an oxygen vacancy-assisted recovery process that reduces the density of dislocations by accelerating the movement of dislocations in ionic crystals under p(O2)-controlled treatment, despite an increase in the density of charged point defects.

    • Daseob Yoon
    • Sangbae Yu
    • Junwoo Son
    Article Open Access
  • A hybrid optofluidic technique was developed to achieve fluid transport with controllable modes and tunable strength. The switch of the optofluidic mode from buoyancy to thermocapillary convection is employed for three-dimensional manipulation. The strong confinement and torque in the convection are capable of trapping and rotating/spinning particles. The buoyancy convection provides a trapping circle to achieve collective trapping and vertical rotation/spin, while the thermocapillary convection offers a trapping lattice to achieve distributed trapping and horizontal rotation/spin. Further investigations in optofluidic arrangement, mixing, and synthesis will broaden its potential applications in the fields of lab-on-a-chip.

    • Jiapeng Zheng
    • Xiaobo Xing
    • Sailing He
    Article Open Access
  • Graphene is very promising for THz application, especially in the fields desiring fast THz imaging, like security screening, communication, biomedical and pharmacy control. However, current graphene-based THz detectors are severely hindered by its poor switching behavior, and lack of internal gain to boost up the responsivity in the framework of plasma-wave self-mixing or thermoelectric detections. A proper means to selectively trigger the photoelectric conversion is highly desirable for practical applications. This work offers alternative way for room temperature THz detection via manipulating the hot carriers either electrically and electromagnetically. Internal photoelectric gain is achieved via the bias-field effect, which leads to the giant enhancement of graphene-based detector’s responsivity over 200 V/W. Furthermore, switching behavior between photoconductive and photovoltaic modes can be given rise in a single device, being promising for scalable THz imaging.

    • Changlong Liu
    • Lei Du
    • Wei Lu
    Article Open Access
  • A novel block copolymer structural color strain sensor was developed, capable of electrically sensing a strain in capacitance change with simultaneous visualization of the strain. A thin mechanochromic bilayer of a block copolymer structural film with 1-D periodic lamellae placed on an ionic gel layer allowed for direct visualization of strain while sensing in capacitance when embedded in an elastomeric dielectric medium. Our block copolymer structural strain sensor was suitable for a reflective mode electronic skin which readily recognized human motion of the finger, elbow, and knee.

    • Tae Hyun Park
    • Seunggun Yu
    • Cheolmin Park
    Article Open Access
  • we present a novel paradigm that suppresses the reflection of light from a metallic surface by using an ultrathin CuO coating. This antireflection concept relies on the strong inference inside the ultrathin absorptive CuO coating. We derive the optimal conditions for minimum reflectance and expound how the film thickness impacts the reflectance. Almost zero reflectance can be obtained at wavelength of ca. 550 nm over a wide range of incident angles. This technology has the potential for many applications, especially viable for photoelctrochemical cells, which requires strong absorption and short carrier collection length.

    • Hongyan Liu
    • Jingjing Peng
    • Yue Yan
    Article Open Access
  • In this work, electrospun In2O3 nanowires with controllable Pt core were designed and prepared as an ultra-sensitive layer with good electron transmission ability as well as high surface area, and then SBA-15 molecular sieve was further integrated as a moisture filter layer. The as-design device was successfully used to detect trace acetone biomarker in exhaled breath, which could accurately distinguish the health people from diabetes in clinical samples.

    • Wei Liu
    • Lin Xu
    • Hongwei Song
    Article Open Access
  • The high performance polymer-based conductive cellular interface was developed by a solvent-assisted crystallization of PEDOT:PSS. The crystallized PEDOT:PSS(c-PEDOT:PSS) exhibited mechanical and electrical robustness over 21days as well as excellent electrical conductivity and electrochemical activities. Thanks to such advantageous properties for the cellular interfaces, the beating rates of cardiomyocytes cultured on c-PEDOT:PSS were successfully modulated through pulsed direct stimulation under 1 V. In addition, c-PEDOT:PSS incorporated Multielectrode arrays (MEAs) recorded real-time action potentials originated from cardiomyocytes with high signal fidelity. we expect c-PEDOT:PSS with high-performance and high-stability to be a promising candidate for long-term bioelectronic interface development.

    • Seong-Min Kim
    • Nara Kim
    • Myung-Han Yoon
    Article Open Access
  • As a new two-dimensional (2D) material, monolayer ruthenium oxide (RuO2) nanosheets (NSs) have distorted h-MX2 type crystal structures that lead to semiconducting properties and good optical transmittance. This study suggests that monolayer RuO2 can be useful in applications of flexible optoelectronics.

    • Dong-Su Ko
    • Woo-Jin Lee
    • Jong Wook Roh
    Article Open Access
  • An amphiphilic dendrimer engineered nanocarrier system (ADENS) possessing a unique hollow core/shell structure is developed, in which siRNA is incorporated in the hydrophilic cavity and paclitaxel is abundantly depoted in the hydrophobic interlayer. Then, the ADENS is modified by tumor microenvironment-sensitive polypeptides (TMSP). The TMSP-ADENS shows enhanced cellular uptake, tumor penetration and accumulation in a MMP-2/9-triggered mechanism. The TMSP-ADENS provides a potential strategy for effective co-delivery of siRNA and paclitaxel for anti-tumor therapy in a synergistic manner.

    • Xin Li
    • A-ning Sun
    • Xian-rong Qi
    Article Open Access
  • Large inhomogeneous electronic states in rare-earth-doped CaFe2As2 produce striking results of manipulating the superconducting phases via current-driven magnetic state. Magnetization hysteresis loops at superconducting state (2 K) and normal state (50 K) for La-doped CaFe2As2 are largely changed by the electric current because their high-Tc regions are localized. Current path between high-Tc regions is considered as a long wire, thus current-induced large magnetic field around the path can modulate the magnetic state in normal/weak superconducting regions. These observations provide new insights into the role of Fe in the Fe-based superconductors and ideas for the design of new superconducting devices.

    • Soon-Gil Jung
    • Soohyeon Shin
    • Tuson Park
    Article Open Access
  • A high density of “accordion-like” silver nanorod array over a large area (~cm2) was fabricated by confining lamellar-forming polystyrene-block-poly (methyl methacrylate) copolymer (PS-b-PMMA) inside cylindrical pores of aluminum oxide (AAO) template grafted by thin neutral brush layers. After removing the AAO template, a 5 nm thick layer of silver was thermally deposited on only PS nanodomains. Owing to combination of hemispherical head and side silver rings, multiple resonances exhibited in the visible and NIR regimes. This sophisticated fabrication utilizing block copolymer self-assembly could be applied to multi-analyte detection and realization of large-scale metamaterials working at visible and NIR wavelengths.

    • Mooseong Kim
    • Jungho Mun
    • Jin Kon Kim
    Article Open Access
  • The copper nanofibrils are formed at the void inside the long continuous carbon nanotube (CNT) fiber by electroplating. Electrical conduction through the composite fiber was dominated by the nanofibrils even though their cross-sectional area is much smaller than that of CNTs. The nanofibrils could carry a very high current density due to their bamboo-like structure and the thermal dissipation through CNTs.

    • Hokyun Rho
    • Min Park
    • Sang Hyun Lee
    Article Open Access
  • A pH-responsive superwetting surface is fabricated and applied as a point-of-care testing platform for naked eye biosensing. Because of the outstanding switching between superhydrophilicity and superhydrophobicity, contact angle based biosensing method is developed for pH, urea, and glucose detection. Especially, non-invasive detection of glucose is achieved for diabetes diagnosis and exercise monitoring. Given to its low cost, instrument-free, disposable, and rapid response (within 1 s), this strategy not only provides a universal platform of point-of-care testing but also extends the industrial-scale application of bioinspired superwettability systems.

    • Zhong Feng Gao
    • Ei Ei Sann
    • Lei Jiang
    Article Open Access
  • We present piezoresistive electronic skins with tunable force sensitivity and selectivity in response to multidirectional forces (normal, shear, tensile, bending) by engineering microstructure geometries (dome, pyramid, pillar). Microdome structures present the best force sensitivities for normal, tensile, and bending stresses. On the other hand, for shear stress, micropillar structures exhibit the highest sensitivity. As proof-of-concept demonstrations, the e-skins are used for wearable healthcare devices to precisely monitor various bio-signals including sound, human breath, and artery/carotid pulse pressures.

    • Jonghwa Park
    • Jinyoung Kim
    • Hyunhyub Ko
    Article Open Access
  • A creative approach to substantially enhance both the strength and ductility of SLM-printed metal parts was successfully demonstrated on the ubiquitous marine-grade stainless steel 316L. The new discovery improves the strength and ductility of stainless steel parts by ~16% and 40% compared with the typical 3D printing process and conventional manufacturing methods. Control of the crystallographic texture is key for this breakthrough, which was achieved by tailoring the geometrical features of the melt pool involved in the laser-based 3D printing process. The desired <011> crystallographic texture favors the activation of the nano-twinning mechanism, which simultaneously enhances the strength and ductility.

    • Zhongji Sun
    • Xipeng Tan
    • Chee Kai Chua
    Article Open Access
  • Cryothermal cycling can induce rejuvenation as well as relaxation of metallic glasses. The surface apparent Young’s modulus and its spatial distribution width increase after the treatment, while in bulk effect depends on the glass composition. This increase is temporary and disappears after some time of room temperature aging. Effect is connected with a large distribution of relaxation times in metallic glasses due to their heterogeneous structure and the formation of complex native oxide on the glass surface. Cryothermal cycling can improve or degrade the plasticity of metallic glasses and the atomic bond structure determines the outcome of the treatment.

    • Sergey V. Ketov
    • Artem S. Trifonov
    • Alan Lindsay Greer
    Article Open Access
  • In this study, the transparent polymer resin in visible wavelength ranges yet ironically be curable by visible light is introduced for stereolithography three-dimensional printings. The key is to use the photoinitiator, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (DPTBP), which generates radicals at the edge wavelength of visible light ranges (~420 nm). The developed resin has high transparency, commercial dyes incorporations, and superior mechanical strength to the existing resins.

    • Hong Key Park
    • Mikyung Shin
    • Haeshin Lee
    Article Open Access