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  • The figure depicts a new type of transparent electrode recording array made of vertically aligned zinc oxide nanotubes grown on graphene (top middle). The nanotubes are formed by sharp nanowalls to penetrate the cell (top left) while transparent graphene layers allow imaging the neurons using with conventional microscopy (top right). As a result, simultaneous recording of electrical signals was obtained from multiple neurons at single-cell resolution. Moreover, the signals had distinguishable waveforms that implicated extracellular- and intracellular-like electrophysiological voltage changes (bottom).

    • Jamin Lee
    • Keundong Lee
    • Gyu-Chul Yi
    ArticleOpen Access
  • A biodegradable triboelectric nanogenerator made from both natural and synthetic biodegradable materials that is utilized to collect mechanical energy in vivo and transduce it into electricity. Reed film and polylactic acid were chosen among different biodegradable materials as the triboelectric layers due to having the best output performance. The nanogenerator was connected to an interdigital electrode to generate an electric field, which stimulated the accelerated release of doxorubicin from red blood cells in targeted drug delivery systems. The release of doxorubicin normalized, facilitating the precise killing of cancer cells, demonstrating the broad potential in the field of cancer treatments.

    • Gang Jian
    • Shangtao Zhu
    • Ching-Ping Wong
    ArticleOpen Access
  • Cryomicroneedles (cryoMNs) permit the precise delivery of therapeutic cells into the skin, but are limited by the cold-chain transportation and storage. This article introduces an innovative solution to use a prefabricated porous microneedle scaffold that can be shipped at room temperature and allow on-site cell loading and usage in the clinic (i.e., the second generation cryoMNs or S-cryoMNs). The study investigates the loading and intradermal delivery of three cell types in clinically relevant in vitro and in vivo models, including mesenchymal stem cells for wound healing, melanocytes for vitiligo treatment, and antigen-pulsed dendritic cells for cancer vaccination.

    • Mengjia Zheng
    • Tianli Hu
    • Chenjie Xu
    ArticleOpen Access
  • Topological transition of a bubble to a skyrmion by the controlled magnetic monopoles injection in Fe/Gd magnetic multilayers. The magnetic monopoles injected from the top and bottom surfaces are topologically characterized by Q = −1 and Q = +1, respectively.

    • Hee-Sung Han
    • Sergio A. Montoya
    • Mi-Young Im
    ArticleOpen Access
  • In this paper, we report the dimensional control of the interface coupling-induced ferromagnetic phase in perovskite-CaRuO3/infinite-layered-SrCuO2 superlattices. The Hall and magnetoresistance measurements indicate the appearance of an interfacial ferromagnetic state in the originally paramagnetic CaRuO3 layers when the CaRuO3 layer is in proximity to the chain-type SrCuO2 layers; this superlattice has the highest Curie temperature of ~75 K and perpendicular magnetic anisotropy. Along with the thickness-driven structural transition from chain-type to planar-type of the SrCuO2 layers, the interfacial ferromagnetic order gradually deteriorates and finally disappears.

    • Li Zhe
    • Shi Wenxiao
    • Jirong Sun
    ArticleOpen Access
  • Wearable devices provide an alternative way to clinically diagnose respiratory diseases in a non-invasive and real-time manner. In this review, we summarize the recent developments in the field of wearable respiratory sensors, including the methods to synthesize various sensing materials, the ways to improve respiratory sensing performances, and the feature comparison among different sensing materials. We also summarize the concentrations, sources and associated diseases of various biomarkers in exhaled gas. Finally, we discuss current trends in the field to provide predictions for the future trajectory of wearable respiratory sensors.

    • Zhifu Yin
    • Yang Yang
    • Xue Yang
    Review ArticleOpen Access
  • The lymphatic system is essential for maintaining homeostasis of our body. Understanding the impact of environmental factors on the lymphatic system and regulating its condition are therefore crucial. We developed a microfluidic device culturing functional skin barrier and lymphatic vessel monolayer. A deep-learning algorithm was employed to validate the pro-lymphangiogenic character of a natural substance Lymphanax™, an extract of Panax Ginseng root. We foresee this platform functioning as a valuable research tool for the pharmaceutical and cosmetic industries, replacing the need for animal models.

    • Minseop Kim
    • Sieun Choi
    • Phil June Park
    ArticleOpen Access
  • We investigate the anomalous transverse conductivities of a two-dimensional (2D) magnetic Fe3GaTe2 system (monolayer to four-layer thickness). A giant anomalous thermal Hall conductivity (ATHC) of -0.14 W/K.m is obtained in the four-layer structure, and this value is comparable to the typical ATHC found in bulk materials which is rare to find in low-dimensional systems. Our findings suggest that the ultra-thin 2D Fe3GaTe2 system could be a promising platform for future spintronics and spin caloritronics device applications.

    • Brahim Marfoua
    • Jisang Hong
    ArticleOpen Access
  • The ultrabroadband absorptive refractory plasmonics is demonstrated with TiN and TiO2 deposited onto an anodized aluminum oxide template. The absorber shows ultrabroadband absorption in the solar spectrum (400–2500 nm). Furthermore, the absorber shows an extended hot carrier lifetime and improved efficiency of photocatalytic hydrogen production. This novel ultrabroadband absorber has great potential to provide a sustainable and cost-effective route for hydrogen generation from solar energy.

    • Myeongcheol Go
    • Inju Hong
    • Jin Kon Kim
    ArticleOpen Access
  • Biomaterial fabrication techniques and therapeutic strategies for spinal cord injury. This review focuses on the most recent advancements of biomaterial-based therapeutics for the treatment of spinal cord injury. The outer ring of the figure shows four fabrication techniques for tissue engineering: hydrogel, electrospinning, 3D printing and decellularization. The inner ring shows the injured spinal cord and the roles of biomaterials in spinal cord injury repair, for instance, restoring the blood‒spinal cord barrier (BSCB).

    • Keyi Chen
    • Wei Yu
    • Huajiang Chen
    Review ArticleOpen Access
  • Magnonic noise has unveiled magnon dynamics, including nonlinear scattering processes.

    • Ryo Furukawa
    • Shoki Nezu
    • Koji Sekiguchi
    ArticleOpen Access
  • This study explores a novel approach to achieve field-free current-driven spin–orbit torque switching of perpendicular magnetization for MRAM applications. By adjusting growth protocols in Pt-based magnetic heterostructures, a previously overlooked laterally tilted texture and magnetic anisotropy are harnessed. These findings allow deterministic switching of perpendicular magnetization without an external magnetic field. Contrary to conventional assumptions, the observed nonlinear dependence on current density resembles a damping-like torque, challenging previous notions about its origin.

    • Chen-Yu Hu
    • Wei-De Chen
    • Chi-Feng Pai
    ArticleOpen Access
  • Schematic illustrations of the changes in the magnetic anisotropy by an applied electric field (E) in the strain directions are displayed. Under an applied E, the piezoelectric stress in the ferroelectric PMN-PT could be introduced in the tensile and compressive directions using positive and negative bias voltages, respectively, resulting in the changes in the magnetic anisotropy in the Co2FeSi layer. The XMCD spectra of Fe and Co L-edges in Co2FeSi under applying E showed the line shape changes only in the Fe site, which corresponds to the changes of orbital magnetic moment in Fe, while that in Co remains unchanged.

    • Jun Okabayashi
    • Takamasa Usami
    • Kohei Hamaya
    ArticleOpen Access
  • The fabrication and development of high-entropy alloys (HEAs) with exceptional functionalities is a rapidly expanding field. The extrinsic factors, such as the existence of grains and different phases, would complicate understanding the physical phenomena. We classified the epitaxial system into atomic-site disordered (ASD) and amorphous system into structurally disordered (SD) states, respectively, to exclude the extrinsic effects of HEAs. With a comprehensive study of the magnetic and transport properties, we can further promote the research of high entropy systems.

    • Jia-Wei Chen
    • Shih-Hsun Chen
    • Ying-Hao Chu
    ArticleOpen Access
  • With the use of a fluorine-containing block providing a surface tension as low as that of PDMS (19.9 < \(\gamma\) < 21.5 mN/m), the PDMS-b-PPeFPA copolymer is synthesized to create a volume-symmetric lamellar structure. Under the symmetric confinement with simultaneous dual neutral interfaces, lamellar microdomains with a sub-10 nm half-pitch feature size are successfully oriented perpendicular to the interfaces at room temperature (RT). Together with unidirectionally aligned perpendicular lamellae along the electric vector in a short period (0.5 h) at RT, we demonstrate a unidirectional alignment of the perpendicular air–inorganic (oxidized PDMS) lamellae between the electrodes.

    • Seungbae Jeon
    • Seungjae Lee
    • Du Yeol Ryu
    ArticleOpen Access
  • Oxide-based thermoelectric materials that exhibit a high figure of merit are promising because of their good chemical and thermal stabilities and their relative harmlessness compared with chalcogenide-based state-of-the-art thermoelectric materials. The layered barium-cobalt oxide (Ba1/3CoO2) exhibits a record-high ZT of 0.55 at 600 °C in air. The increase in ZT is directly originated by the decreased thermal conductivity of Ba1/3CoO2. As we hypothesized, the greater the atomic mass, the lower the thermal conductivity, resulting in higher ZT. The ZT is reliable and the highest among thermoelectric oxides. Moreover, this value is comparable to those of p-type PbTe and p-type SiGe.

    • Yuqiao Zhang
    • Hiromichi Ohta
    Review ArticleOpen Access
  • Two-dimensional semiconductors are considered as field-effect transistors to overcome short channel effects and reduce the device size. As contacts to the metallic electrodes are decisive for the device performance, we study the electronic properties of contacts between Janus MoSSe and various two-dimensional metals. We demonstrate that weak interactions at these van der Waals contacts suppress Fermi level pinning and show that ohmic contacts can be formed for both terminations of Janus MoSSe, generating favorable transport characteristics.

    • Ning Zhao
    • Shubham Tyagi
    • Udo Schwingenschlögl
    ArticleOpen Access
  • A WO3 nanoneedle film was developed for a gas sensor to detect low concentrations of acetone gas, which is a diabetes biomarker. The sensor exhibited a high response (19.72) to 10 ppmv acetone gas. The sensor also exhibited a high response (25.36) to 1 ppmv NO2, which is related to asthma. The limits of detection for acetone and NO2 gases were estimated to be 2.4 and 1.5 ppbv, respectively. The sensor exhibited superior ability to detect low concentrations of biomarker gases. The unique characteristics of the WO3 nanoneedle film contributed to its high response rates.

    • Yoshitake Masuda
    • Ayako Uozumi
    ArticleOpen Access
  • Malaria continues to be among the most lethal infectious diseases. In the last two decades, we have witnessed unprecedented success in reducing the mortality rate. With the UN resolution of eradicating malaria by 2030 approaching fast, the scientific community has devoted substantial attention to interdisciplinary research using the latest opto-/magnetic-based technologies to detect a novel biomarker coming from the malarial pigment (hemozoin), which also carries vital information for discovering targeted drugs. This perspective article looks into the growing interest in this field and discusses the practical applicability of these sensing technologies.

    • Ashutosh Rathi
    • Z. Chowdhry
    • Weng Kung Peng
    Review ArticleOpen Access
  • This perspective highlights recent applications of ionogels that take advantage of their ionic conductivity, nonvolatility, and high thermal and electrochemical stability. Examples include sensors, batteries, electronics, 3D printing, and adhesives. Improving the mechanical properties of ionogels broadens the application space; thus, simple strategies to achieve tough ionogels are introduced. Finally, the potential applications and future opportunities of ionogels are discussed.

    • Meixiang Wang
    • Jian Hu
    • Michael D. Dickey
    PerspectiveOpen Access