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Xu, Lin

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Xu, Lin

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2013 - 20154

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Author's Publications: search.filters.isAuthorOfPublication.6fa98718-2525-4bc5-9ccf-c65932a4869f

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Now showing 1 - 4 of 4
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    Design and Synthesis of Diverse Functional Kinked Nanowire Structures for Nanoelectronic Bioprobes
    (American Chemical Society, 2013) Xu, Lin; Jiang, Zhe; Qing, Quan; Mai, Liqiang; Zhang, Qingjie; Lieber, Charles
    Functional kinked nanowires (KNWs) represent a new class of nanowire building blocks, in which functional devices, for example, nanoscale field-effect transistors (nanoFETs), are encoded in geometrically controlled nanowire superstructures during synthesis. The bottom-up control of both structure and function of KNWs enables construction of spatially isolated point-like nanoelectronic probes that are especially useful for monitoring biological systems where finely tuned feature size and structure are highly desired. Here we present three new types of functional KNWs including (1) the zero-degree KNW structures with two parallel heavily doped arms of U-shaped structures with a nanoFET at the tip of the “U”, (2) series multiplexed functional KNW integrating multi-nanoFETs along the arm and at the tips of V-shaped structures, and (3) parallel multiplexed KNWs integrating nanoFETs at the two tips of W-shaped structures. First, U-shaped KNWs were synthesized with separations as small as 650 nm between the parallel arms and used to fabricate three-dimensional nanoFET probes at least 3 times smaller than previous V-shaped designs. In addition, multiple nanoFETs were encoded during synthesis in one of the arms/tip of V-shaped and distinct arms/tips of W-shaped KNWs. These new multiplexed KNW structures were structurally verified by optical and electron microscopy of dopant-selective etched samples and electrically characterized using scanning gate microscopy and transport measurements. The facile design and bottom-up synthesis of these diverse functional KNWs provides a growing toolbox of building blocks for fabricating highly compact and multiplexed three-dimensional nanoprobes for applications in life sciences, including intracellular and deep tissue/cell recordings.
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    Free-standing kinked nanowire transistor probes for targeted intracellular recording in three dimensions
    (2013) Qing, Quan; Jiang, Zhe; Xu, Lin; Gao, Ruixuan; Mai, Liqiang; Lieber, Charles
    Recording intracellular bioelectrical signals is central to understanding the fundamental behaviour of cells and cell-networks in, for example, neural and cardiac systems1–4. The standard tool for intracellular recording, the patch-clamp micropipette5 is widely applied, yet remains limited in terms of reducing the tip size, the ability to reuse the pipette5, and ion exchange with the cytoplasm6. Recent efforts have been directed towards developing new chip-based tools1–4,7–13, including micro-to-nanoscale metal pillars7–9, transistor-based kinked nanowire10,11 and nanotube devices12,13. These nanoscale tools are interesting with respect to chip-based multiplexing, but, to date, preclude targeted recording from specific cell regions and/or subcellular structures. Here we overcome this limitation in a general manner by fabricating free-standing probes where a kinked silicon nanowire with encoded field-effect transistor detector serves as the tip end. These probes can be manipulated in three dimensions (3D) within a standard microscope to target specific cells/cell regions, and record stable full-amplitude intracellular action potentials from different targeted cells without the need to clean or change the tip. Simultaneous measurements from the same cell made with free-standing nanowire and patch-clamp probes show that the same action potential amplitude and temporal properties are recorded without corrections to the raw nanowire signal. In addition, we demonstrate real-time monitoring of changes in the action potential as different ion-channel blockers are applied to cells, and multiplexed recording from cells by independent manipulation of two free-standing nanowire probes.
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    General synthesis of complex nanotubes by gradient electrospinning and controlled pyrolysis
    (Nature Pub. Group, 2015) Niu, Chaojiang; Meng, Jiashen; Wang, Xuanpeng; Han, Chunhua; Yan, Mengyu; Zhao, Kangning; Xu, Xiaoming; Ren, Wenhao; Zhao, Yunlong; Xu, Lin; Zhang, Qingjie; Zhao, Dongyuan; Mai, Liqiang
    Nanowires and nanotubes have been the focus of considerable efforts in energy storage and solar energy conversion because of their unique properties. However, owing to the limitations of synthetic methods, most inorganic nanotubes, especially for multi-element oxides and binary-metal oxides, have been rarely fabricated. Here we design a gradient electrospinning and controlled pyrolysis method to synthesize various controllable 1D nanostructures, including mesoporous nanotubes, pea-like nanotubes and continuous nanowires. The key point of this method is the gradient distribution of low-/middle-/high-molecular-weight poly(vinyl alcohol) during the electrospinning process. This simple technique is extended to various inorganic multi-element oxides, binary-metal oxides and single-metal oxides. Among them, Li3V2(PO4)3, Na0.7Fe0.7Mn0.3O2 and Co3O4 mesoporous nanotubes exhibit ultrastable electrochemical performance when used in lithium-ion batteries, sodium-ion batteries and supercapacitors, respectively. We believe that a wide range of new materials available from our composition gradient electrospinning and pyrolysis methodology may lead to further developments in research on 1D systems.
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    Fast Ionic Diffusion-Enabled Nanoflake Electrode by Spontaneous Electrochemical Pre-Intercalation for High-Performance Supercapacitor
    (Nature Publishing Group, 2013) Mai, Liqiang; Li, Han; Zhao, Yunlong; Xu, Lin; Xu, Xu; Luo, Yanzhu; Zhang, Zhengfei; Ke, Wang; Niu, Chaojiang; Zhang, Qingjie
    Layered intercalation compounds Na\(_{x}\)MnO\(_{2}\) (x = 0.7 and 0.91) nanoflakes have been prepared directly through wet electrochemical process with Na\(^{+}\) ions intercalated into MnO\(_{2}\) interlayers spontaneously. The as-prepared Na\(_{x}\)MnO\(_{2}\) nanoflake based supercapacitors exhibit faster ionic diffusion with enhanced redox peaks, tenfold-higher energy densities up to 110 Wh·kg\(^{-1}\) and higher capacitances over 1000 F·g\(^{-1}\) in aqueous sodium system compared with traditional MnO\(_{2}\) supercapacitors. Due to the free-standing electrode structure and suitable crystal structure, Na\(_{x}\)MnO\(_{2}\) nanoflake electrodes also maintain outstanding electrochemical stability with capacitance retention up to 99.9% after 1000 cycles. Besides, pre-intercalation effect is further studied to explain this enhanced electrochemical performance. This study indicates that the suitable pre-intercalation is effective to improve the diffusion of electrolyte cations and other electrochemical performance for layered oxides, and suggests that the as-obtained nanoflakes are promising materials to achieve the hybridization of both high energy and power density for advanced supercapacitors.