Single inorganic–organic hybrid nanowires with ambipolar photoresponse

We report for the first time single nanowires (NWs) with ambipolar (positive/negative) photoresponse that changes sign depending on the illumination wavelength. The single NWs were grown by the meniscus-guided method using inorganic (ZnO nanoparticles)–organic (PEDOT:PSS) hybrid materials. The ambipolar photoresponse of the single NWs enabled us to develop an unprecedented spectrum-discriminating NW photodetector array

Light propagation in conjugated polymer nanowires decoupled from a substrate

Light-emitting conjugated polymer nanowires are vertically grown and remotely manipulated into a freestanding straight or curved structure in three-dimension. This approach enabled us to eliminate substrate coupling, a critical issue in nanowire photonics in the past decade. We for the first time accomplished characterization of propagation and bending losses of nanowires completely decoupled from a substrate

Meniscus-Guided Micro-Printing of Prussian Blue for Smart Electrochromic Display

Using energy-saving electrochromic (EC) displays in smart devices for augmented reality makes cost-effective, easily producible, and efficiently operable devices for specific applications possible. Prussian blue (PB) is a metal-organic coordinated compound with unique EC properties that limit EC display applications due to the difficulty in PB micro-patterning. This work presents a novel micro-printing strategy for PB patterns using localized crystallization of FeFe(CN)(6) on a substrate confined by the acidic-ferric-ferricyanide ink meniscus, followed by thermal reduction at 120 degrees C, thereby forming PB. Uniform PB patterns can be obtained by manipulating printing parameters, such as the concentration of FeCl3 center dot K3Fe(CN)(6), printing speed, and pipette inner diameter. Using a 0.1 M KCl (pH 4) electrolyte, the printed PB pattern is consistently and reversibly converted to Prussian white (CV potential range: -0.2-0.5 V) with 200 CV cycles. The PB-based EC display with a navigation function integrated into a smart contact lens is able to display directions to a destination to a user by receiving GPS coordinates in real time. This facile method for forming PB micro-patterns could be used for advanced EC displays and various functional devices

3D printing of quantum dot embedded polymer nanowires for patterning to triangular-delta and Bayer

This contribution presents a method for producing nanoscale color pixels for high-resolution displays using 3D printing of vertically freestanding nanostructures containing red, green, or blue light-emitting quantum dots (QDs). Traditional methods for producing pixels suffer from decreased brightness and pixel density at higher densities due to the reduced volume, but our 3D printing method allows for individual control of brightness by adjusting pixel height in 3D, resulting in a two-fold increase in brightness without changing lateral dimensions. We demonstrate sub-micrometer pixels representing primary colors at a super-high density, enabling image patterns with a pixel resolution of 8,400 ppi and individual modulation of sub-pixels with a possible pixel resolution of 5,600 ppi in triangular-delta and Bayer type designs. The method can be applied to displays, information storage, cryptography, and image sensors. The 3D printing method is a versatile approach for photonic research and has potential for contributing to the development of a range of applications

Single inorganic-organic hybrid nanowires with ambipolar photoresponse

We report for the first time single nanowires (NWs) with ambipolar (positive/negative) photoresponse that changes sign depending on the illumination wavelength. The single NWs were grown by the meniscus-guided method using inorganic (ZnO nanoparticles)-organic (PEDOT:PSS) hybrid materials. The ambipolar photoresponse of the single NWs enabled us to develop an unprecedented spectrum-discriminating NW photodetector array.open111212sciescopu

3-D Worm Tracker for Freely Moving C. elegans

The manner in which the nervous system regulates animal behaviors in natural environments is a fundamental issue in biology. To address this question, C. elegans has been widely used as a model animal for the analysis of various animal behaviors. Previous behavioral assays have been limited to two-dimensional (2-D) environments, confining the worm motion to a planar substrate that does not reflect three-dimensional (3-D) natural environments such as rotting fruits or soil. Here, we develop a 3-D worm tracker (3DWT) for freely moving C. elegans in 3-D environments, based on a stereoscopic configuration. The 3DWT provides us with a quantitative trajectory, including the position and movement direction of the worm in 3-D. The 3DWT is also capable of recording and visualizing postures of the moving worm in 3-D, which are more complex than those in 2-D. Our 3DWT affords new opportunities for understanding the nervous system function that regulates animal behaviors in natural 3-D environments.X11119sciescopu

Light propagation in conjugated polymer nanowires decoupled from a substrate

Light-emitting conjugated polymer nanowires are vertically grown and remotely manipulated into a freestanding straight or curved structure in three-dimension. This approach enabled us to eliminate substrate coupling, a critical issue in nanowire photonics in the past decade. We for the first time accomplished characterization of propagation and bending losses of nanowires completely decoupled from a substrate. © 2014 the Partner Organisations.Link_to_subscribed_fulltex

Precise Placement of Microbubble Templates at Single Entity Resolution

Microbubbles have been used as a soft template to produce hollow structures for diverse applications in chemistry, materials science, and biomedicine. It is a challenge, however, to control their size and position at single entity level. We report on an on-demand method to produce and place a single microbubble with programmed size and position. The method exploits scanning an electrolyte-filled micropipette to place a hydrogen (H-2) bubble, generated by water electrolysis, on the desired position. The bubble growth is self-limited after the bubble size fits to the pipet aperture, yielding well-controlled bubble size. The bubble growth dynamics within the pipet is successfully investigated by a methodology that combines phase-contrast X-ray imaging and electric-current measurement. We show that the microbubbles, accurately controlled in size and position, can be used for the fabrication of various polypyrrole microcontainer arrays. We expect the scanning-pipet strategy could be generalized for manipulating various soft materials at will.11Nsciescopu

3-D Worm Tracker for Freely Moving <em>C. elegans</em>

<div><p>The manner in which the nervous system regulates animal behaviors in natural environments is a fundamental issue in biology. To address this question, <i>C. elegans</i> has been widely used as a model animal for the analysis of various animal behaviors. Previous behavioral assays have been limited to two-dimensional (2-D) environments, confining the worm motion to a planar substrate that does not reflect three-dimensional (3-D) natural environments such as rotting fruits or soil. Here, we develop a 3-D worm tracker (3DWT) for freely moving <i>C. elegans</i> in 3-D environments, based on a stereoscopic configuration. The 3DWT provides us with a quantitative trajectory, including the position and movement direction of the worm in 3-D. The 3DWT is also capable of recording and visualizing postures of the moving worm in 3-D, which are more complex than those in 2-D. Our 3DWT affords new opportunities for understanding the nervous system function that regulates animal behaviors in natural 3-D environments.</p> </div

Colloidal wettability probed with X-ray microscopy

Colloids (colloidal particles or nanoparticles) and their in-situ characterizations are important topics in colloid and interface science. In-situ visualization of colloids with X-ray microscopy is a growing frontier. Here, after a brief introduction on the method, we focus on its application for identifying nanoscale wettability of colloidal particles at fluid interfaces, which is a critical factor in colloidal self-assembly. We discuss a quantitative study on colloidal wettability with two microscopic methods: (i) X-ray microscopy by visualizing natural oil-water interfaces and (ii) confocal microscopy by visualizing fluorescently-labeled interfaces. Both methods show consistent estimation results in colloid-fluid interfacial tensions. This comparison strongly suggests a feasibility of X-ray microscopy as a promising in-situ protocol in colloid research, without fluorescent staining. Finally, we address a prospect of X-ray imaging for colloid and interface science. © 2012 Elsevier Ltd.Link_to_subscribed_fulltex