The Experts below are selected from a list of 8256 Experts worldwide ranked by ideXlab platform
Peilin Chen - One of the best experts on this subject based on the ideXlab platform.
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Flexible Nanopillars to regulate cell adhesion and movement.
Nanotechnology, 2016Co-Authors: Fan-ching Chien, Yang-hong Dai, Chiung Wen Kuo, Peilin ChenAbstract:Flexible polymer Nanopillar substrates were used to systematically demonstrate cell alignment and migration guided by the directional formation of focal adhesions. The polymer Nanopillar substrates were constructed to various height specifications to provide an extensive variation of flexibility; a rectangular arrangement created spatial confinement between adjacent Nanopillars, providing less spacing in the horizontal and vertical directions. Three polymer Nanopillar substrates with the diameter of 400 nm and the heights of 400, 800, and 1200 nm were fabricated. Super-resolution localization imaging and protein pair-distance analysis of vinculin proteins revealed that Chinese hamster ovary (CHO) cells formed mature focal adhesions on 1200 nm high Nanopillar substrates by bending adjacent Nanopillars to link dot-like adhesions. The spacing confinement of the adjacent Nanopillars enhanced the orthogonal directionality of the formation tendency of the mature focal adhesions. The directional formation of the mature focal adhesions also facilitated the organization of actin filaments in the horizontal and vertical directions. Moreover, 78% of the CHO cells were aligned in these two directions, in conformity with the flexibility and nanotopographical cues of the Nanopillars. Biased cell migration was observed on the 1200 nm high Nanopillar substrates.
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Polymeric Nanopillar arrays for cell traction force measurements.
Electrophoresis, 2010Co-Authors: Chiung Wen Kuo, Fan-ching Chien, Jau-ye Shiu, Shih-min Tsai, Di-yan Chueh, Peilin ChenAbstract:This paper reports the development of a novel force measurement device based on polymeric Nanopillar arrays. The device was fabricated by a process combining nanosphere lithography, oxygen plasma treatment, deep etching and nano-molding. Well-ordered polymeric Nanopillar arrays with various diameters and aspect ratios were fabricated and used as cell culture substrates. Cell traction forces were measured by the deflection of the Nanopillars. Since the location of the Nanopillars can be monitored at all times, this device allows for the measurement of the evolution of adhesion forces over time.
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fabrication of size tunable large area periodic silicon Nanopillar arrays with sub 10 nm resolution
Journal of Physical Chemistry B, 2003Co-Authors: Chun-wen Kuo, Peilin Chen, Jau-ye Shiu, Gabor A SomorjaiAbstract:Here, we present a fabrication procedure that can produce large-area, size-tunable, periodic silicon Nanopillar arrays, using metal templates that are created via nanosphere lithography. The size of the silicon Nanopillars can be systematically controlled by an oxidation and etching process. The smallest size of Nanopillars fabricated via this method is ∼9 nm, and the area covered with Nanopillars is >1 cm2. Using this approach and nanoimprint lithography, it is possible to pattern sub-10-nm metal nanoparticles with a particle density as high as 1 × 109 particles/cm2.
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Size- and Shape-Controlled Fabrication of Large-Area Periodic Nanopillar Arrays
Chemistry of Materials, 2003Co-Authors: Chun-wen Kuo, Jau-ye Shiu, Peilin ChenAbstract:A simple process for the fabrication of large-area well-ordered periodic Nanopillar arrays have been developed based on a combination of colloidal lithography and etching techniques. Large-area Nanopillar arrays have been successfully fabricated by this approach. The lateral dimensions of Nanopillars as small as 40 nm and the aspect ratio as high as 7:1 have been achieved. Our results indicate that it is possible to control the size, shape, and height of Nanopillar arrays by fine-tuning the etching recipes. These periodic Nanopillar arrays can be used as stamps for nanoimprinting lithography and contact printing lithography to produce more complex periodic nanostructures.
Zhiyong Fan - One of the best experts on this subject based on the ideXlab platform.
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In situ doping control and electrical transport investigation of single and arrayed CdS Nanopillars
Nanoscale, 2013Co-Authors: Xi Liu, Kyungmook Kwon, Min Hyung Lee, Yu-lun Chueh, Zhiyong FanAbstract:Highly aligned intrinsic and indium doped CdS Nanopillar arrays were fabricated via a template assisted Solid Source Chemical Vapor Deposition method (SSCVD). The prepared Nanopillar arrays were well aligned, dense and uniform in diameter and length. Their geometry can be well defined by the design of the templates. These unique properties make them promising candidates for future photonic and optoelectronic devices. The structure of the prepared Nanopillars has been studied by high resolution transmission electron microscopy and their different growth orientation as compared to those grown in free space has been observed and interpreted by the template induced change of the liquid-solid interfacial energy and the surface tension at the edge of the circular interface. To investigate electrical property of CdS Nanopillars, vertical Nanopillar array devices and horizontal individual Nanopillar field-effect transistors have been fabricated and characterized. The measurements showed that the location of the indium doping source significantly affected carrier concentration, conductivity and field-effect mobility of the prepared CdS Nanopillars. Particularly, it was found that conductivity could be improved by 4 orders of magnitude and field-effect mobility could be enhanced up to 50 cm(2) V(-1) s(-1) via proper doping control. These results enable further applications of CdS Nanopillars in nano-optoelectronic applications such as photodetection and photovoltaics in the future.
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shape controlled synthesis of single crystalline Nanopillar arrays by template assisted vapor liquid solid process
Journal of the American Chemical Society, 2010Co-Authors: Onur Ergen, Daniel J. Ruebusch, Asghar A. Rathore, Zhiyong Fan, Rehan Kapadia, Hui Fang, Kuniharu Takei, Arash Jamshidi, Ali JaveyAbstract:Highly regular, single-crystalline Nanopillar arrays with tunable shapes and geometry are synthesized by the template-assisted vapor−liquid−solid growth mechanism. In this approach, the grown Nanopillars faithfully reproduce the shape of the pores because during the growth the liquid catalyst seeds fill the space available, thereby conforming to the pore geometry. The process is highly generic for various material systems, and as an example, CdS and Ge Nanopillar arrays with square, rectangular, and circular cross sections are demonstrated. In the future, this technique can be used to engineer the intrinsic properties of NPLs as a function of three independently controlled dimensional parameters - length, width and height.
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Challenges and prospects of Nanopillar-based solar cells
Nano Research, 2009Co-Authors: Zhiyong Fan, Onur Ergen, Daniel J. Ruebusch, Asghar A. Rathore, Paul W. Leu, Rehan Kapadia, Ali JaveyAbstract:Materials and device architecture innovations are essential for further enhancing the performance of solar cells while potentially enabling their large-scale integration as a viable source of alternative energy. In this regard, tremendous research has been devoted in recent years with continuous progress in the field. In this article, we review the recent advancements in Nanopillar-based photovoltaics while discussing the future challenges and prospects. Nanopillar arrays provide unique advantages over thin films in the areas of optical properties and carrier collection, arising from their three-dimensional geometry. The choice of the material system, however, is essential in order to gain the advantage of the large surface/interface area associated with Nanopillars with the constraints different from those of the thin film devices.
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three dimensional Nanopillar array photovoltaics on low cost and flexible substrates
Nature Materials, 2009Co-Authors: Onur Ergen, Zhiyong Fan, Yu-lun Chueh, Haleh Razavi, Aimee MoriwakiAbstract:Solar power is an important part of the strategy towards using more renewable energy. The development of low-cost photovoltaic Nanopillar structures fabricated on thin aluminium substrates will contribute to this effort, as it promises new applications for flexible, mass-produced solar cells. Solar energy represents one of the most abundant and yet least harvested sources of renewable energy. In recent years, tremendous progress has been made in developing photovoltaics that can be potentially mass deployed1,2,3. Of particular interest to cost-effective solar cells is to use novel device structures and materials processing for enabling acceptable efficiencies4,5,6. In this regard, here, we report the direct growth of highly regular, single-crystalline Nanopillar arrays of optically active semiconductors on aluminium substrates that are then configured as solar-cell modules. As an example, we demonstrate a photovoltaic structure that incorporates three-dimensional, single-crystalline n-CdS Nanopillars, embedded in polycrystalline thin films of p-CdTe, to enable high absorption of light and efficient collection of the carriers. Through experiments and modelling, we demonstrate the potency of this approach for enabling highly versatile solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency arising from the geometric configuration of the Nanopillars.
Ali Javey - One of the best experts on this subject based on the ideXlab platform.
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molecular monolayers for conformal nanoscale doping of inp Nanopillar photovoltaics
Applied Physics Letters, 2011Co-Authors: Kee Young Cho, Onur Ergen, Daniel J. Ruebusch, Rehan Kapadia, Min Hyung Lee, Kuniharu Takei, Jaehyun Moon, Alexandra C Ford, Ali JaveyAbstract:Semiconductor Nanopillar arrays with radially doped junctions have been widely proposed as an attractive device architecture for cost effective and high efficiency solar cells. A challenge in the fabrication of three-dimensional Nanopillar devices is the need for highly abrupt and conformal junctions along the radial axes. Here, a sulfur monolayer doping scheme is implemented to achieve conformal ultrashallow junctions with sub-10 nm depths and a high electrically active dopant concentration of 1019–1020 cm−3 in arrays of InP Nanopillars. The enabled solar cells exhibit a respectable conversion efficiency of 8.1% and a short circuit current density of 25 mA/cm3. The work demonstrates the utility of well-established surface chemistry for fabrication of nonplanar junctions for complex devices.
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shape controlled synthesis of single crystalline Nanopillar arrays by template assisted vapor liquid solid process
Journal of the American Chemical Society, 2010Co-Authors: Onur Ergen, Daniel J. Ruebusch, Asghar A. Rathore, Zhiyong Fan, Rehan Kapadia, Hui Fang, Kuniharu Takei, Arash Jamshidi, Ali JaveyAbstract:Highly regular, single-crystalline Nanopillar arrays with tunable shapes and geometry are synthesized by the template-assisted vapor−liquid−solid growth mechanism. In this approach, the grown Nanopillars faithfully reproduce the shape of the pores because during the growth the liquid catalyst seeds fill the space available, thereby conforming to the pore geometry. The process is highly generic for various material systems, and as an example, CdS and Ge Nanopillar arrays with square, rectangular, and circular cross sections are demonstrated. In the future, this technique can be used to engineer the intrinsic properties of NPLs as a function of three independently controlled dimensional parameters - length, width and height.
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Challenges and prospects of Nanopillar-based solar cells
Nano Research, 2009Co-Authors: Zhiyong Fan, Onur Ergen, Daniel J. Ruebusch, Asghar A. Rathore, Paul W. Leu, Rehan Kapadia, Ali JaveyAbstract:Materials and device architecture innovations are essential for further enhancing the performance of solar cells while potentially enabling their large-scale integration as a viable source of alternative energy. In this regard, tremendous research has been devoted in recent years with continuous progress in the field. In this article, we review the recent advancements in Nanopillar-based photovoltaics while discussing the future challenges and prospects. Nanopillar arrays provide unique advantages over thin films in the areas of optical properties and carrier collection, arising from their three-dimensional geometry. The choice of the material system, however, is essential in order to gain the advantage of the large surface/interface area associated with Nanopillars with the constraints different from those of the thin film devices.
Onur Ergen - One of the best experts on this subject based on the ideXlab platform.
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molecular monolayers for conformal nanoscale doping of inp Nanopillar photovoltaics
Applied Physics Letters, 2011Co-Authors: Kee Young Cho, Onur Ergen, Daniel J. Ruebusch, Rehan Kapadia, Min Hyung Lee, Kuniharu Takei, Jaehyun Moon, Alexandra C Ford, Ali JaveyAbstract:Semiconductor Nanopillar arrays with radially doped junctions have been widely proposed as an attractive device architecture for cost effective and high efficiency solar cells. A challenge in the fabrication of three-dimensional Nanopillar devices is the need for highly abrupt and conformal junctions along the radial axes. Here, a sulfur monolayer doping scheme is implemented to achieve conformal ultrashallow junctions with sub-10 nm depths and a high electrically active dopant concentration of 1019–1020 cm−3 in arrays of InP Nanopillars. The enabled solar cells exhibit a respectable conversion efficiency of 8.1% and a short circuit current density of 25 mA/cm3. The work demonstrates the utility of well-established surface chemistry for fabrication of nonplanar junctions for complex devices.
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shape controlled synthesis of single crystalline Nanopillar arrays by template assisted vapor liquid solid process
Journal of the American Chemical Society, 2010Co-Authors: Onur Ergen, Daniel J. Ruebusch, Asghar A. Rathore, Zhiyong Fan, Rehan Kapadia, Hui Fang, Kuniharu Takei, Arash Jamshidi, Ali JaveyAbstract:Highly regular, single-crystalline Nanopillar arrays with tunable shapes and geometry are synthesized by the template-assisted vapor−liquid−solid growth mechanism. In this approach, the grown Nanopillars faithfully reproduce the shape of the pores because during the growth the liquid catalyst seeds fill the space available, thereby conforming to the pore geometry. The process is highly generic for various material systems, and as an example, CdS and Ge Nanopillar arrays with square, rectangular, and circular cross sections are demonstrated. In the future, this technique can be used to engineer the intrinsic properties of NPLs as a function of three independently controlled dimensional parameters - length, width and height.
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Challenges and prospects of Nanopillar-based solar cells
Nano Research, 2009Co-Authors: Zhiyong Fan, Onur Ergen, Daniel J. Ruebusch, Asghar A. Rathore, Paul W. Leu, Rehan Kapadia, Ali JaveyAbstract:Materials and device architecture innovations are essential for further enhancing the performance of solar cells while potentially enabling their large-scale integration as a viable source of alternative energy. In this regard, tremendous research has been devoted in recent years with continuous progress in the field. In this article, we review the recent advancements in Nanopillar-based photovoltaics while discussing the future challenges and prospects. Nanopillar arrays provide unique advantages over thin films in the areas of optical properties and carrier collection, arising from their three-dimensional geometry. The choice of the material system, however, is essential in order to gain the advantage of the large surface/interface area associated with Nanopillars with the constraints different from those of the thin film devices.
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three dimensional Nanopillar array photovoltaics on low cost and flexible substrates
Nature Materials, 2009Co-Authors: Onur Ergen, Zhiyong Fan, Yu-lun Chueh, Haleh Razavi, Aimee MoriwakiAbstract:Solar power is an important part of the strategy towards using more renewable energy. The development of low-cost photovoltaic Nanopillar structures fabricated on thin aluminium substrates will contribute to this effort, as it promises new applications for flexible, mass-produced solar cells. Solar energy represents one of the most abundant and yet least harvested sources of renewable energy. In recent years, tremendous progress has been made in developing photovoltaics that can be potentially mass deployed1,2,3. Of particular interest to cost-effective solar cells is to use novel device structures and materials processing for enabling acceptable efficiencies4,5,6. In this regard, here, we report the direct growth of highly regular, single-crystalline Nanopillar arrays of optically active semiconductors on aluminium substrates that are then configured as solar-cell modules. As an example, we demonstrate a photovoltaic structure that incorporates three-dimensional, single-crystalline n-CdS Nanopillars, embedded in polycrystalline thin films of p-CdTe, to enable high absorption of light and efficient collection of the carriers. Through experiments and modelling, we demonstrate the potency of this approach for enabling highly versatile solar modules on both rigid and flexible substrates with enhanced carrier collection efficiency arising from the geometric configuration of the Nanopillars.
Bianxiao Cui - One of the best experts on this subject based on the ideXlab platform.
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Characterization of the cell-Nanopillar interface by transmission electron microscopy.
Nano letters, 2012Co-Authors: Lindsey Hanson, Ziliang Carter Lin, Chong Xie, Yi Cui, Bianxiao CuiAbstract:Vertically aligned Nanopillars can serve as excellent electrical, optical and mechanical platforms for biological studies. However, revealing the nature of the interface between the cell and the Nanopillar is very challenging. In particular, a matter of debate is whether the cell membrane remains intact around the Nanopillar. Here we present a detailed characterization of the cell-Nanopillar interface by transmission electron microscopy. We examined cortical neurons growing on Nanopillars with diameter 50–500 nm and heights 0.5–2 μm. We found that on Nanopillars less than 300 nm in diameter, the cell membrane wraps around the entirety of the Nanopillar without the Nanopillar penetrating into the interior of the cell. On the other hand, the cell sits on top of arrays of larger, closely spaced Nanopillars. We also observed that the membrane-surface gap of both cell bodies and neurites is smaller for Nanopillars than for a flat substrate. These results support a tight interaction between the cell membrane an...
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Vertical Nanopillars for highly localized fluorescence imaging
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Chong Xie, Lindsey Hanson, Yi Cui, Bianxiao CuiAbstract:Observing individual molecules in a complex environment by fluorescence microscopy is becoming increasingly important in biological and medical research, for which critical reduction of observation volume is required. Here, we demonstrate the use of vertically aligned silicon dioxide Nanopillars to achieve below-the-diffraction-limit observation volume in vitro and inside live cells. With a diameter much smaller than the wavelength of visible light, a transparent silicon dioxide Nanopillar embedded in a nontransparent substrate restricts the propagation of light and affords evanescence wave excitation along its vertical surface. This effect creates highly confined illumination volume that selectively excites fluorescence molecules in the vicinity of the Nanopillar. We show that this Nanopillar illumination can be used for in vitro single-molecule detection at high fluorophore concentrations. In addition, we demonstrate that vertical Nanopillars interface tightly with live cells and function as highly localized light sources inside the cell. Furthermore, specific chemical modification of the Nanopillar surface makes it possible to locally recruit proteins of interest and simultaneously observe their behavior within the complex, crowded environment of the cell.
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Noninvasive neuron pinning with Nanopillar arrays.
Nano letters, 2010Co-Authors: Chong Xie, Lindsey Hanson, Bianxiao Cui, Wenjun Xie, Ziliang Lin, Yi CuiAbstract:Cell migration in a cultured neuronal network presents an obstacle to selectively measuring the activity of the same neuron over a long period of time. Here we report the use of Nanopillar arrays to pin the position of neurons in a noninvasive manner. Vertical Nanopillars protruding from the surface serve as geometrically better focal adhesion points for cell attachment than a flat surface. The cell body mobility is significantly reduced from 57.8 μm on a flat surface to 3.9 μm on Nanopillars over a 5 day period. Yet, neurons growing on Nanopillar arrays show a growth pattern that does not differ in any significant way from that seen on a flat substrate. Notably, while the cell bodies of neurons are efficiently anchored by the Nanopillars, the axons and dendrites are free to grow and elongate into the surrounding area to develop a neuronal network, which opens up opportunities for long-term study of the same neurons in connected networks.
