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Sung-Ho Shin, Seong-Young Choi, Min Hyung Lee, Junghyo Nah
We report high performance piezoelectric nanogenerators (PENGs) with nanoimprinted sol-gel BaTiO3 (BTO) nanopillar array polarized under high electric field and ultraviolet. The PENGs fabricated using this method demonstrate greatly enhanced output voltage of ~10 V and current density of ~1.2 μA cm-2, respectively, in comparison to that of flat PENG. Further, the PENG demonstrates uniform output characteristics over the entire device area thanks to uniform nanoimprint pillar array. The approach introduced here is simple, effective, reliable, and reproducible way to fabricate high performance sol-gel based PENGs and electronic devices...
November 13, 2017: ACS Applied Materials & Interfaces
Yu Liu, Wen Huang, Tianxun Gong, Yue Su, Hua Zhang, Yiwen He, Zhiwei Liu, Bin Yu
Graphene has been demonstrated as a candidate for optoelectronic devices due to its broad absorption spectrum and ultra-high carrier mobility. However, graphene is essentially transparent in visible and near-infrared regimes with an absorptivity of 2.3%, which largely limits its application in photodetection. Here, we show that metallic nanopillar antennas could improve light absorption in graphene detectors. The coupled antennas help to concentrate a free space electromagnetic wave around the nanopillars by localized surface plasmon resonance, strongly impacted by geometrical design...
November 16, 2017: Nanoscale
Denver P Linklater, Saulius Juodkazis, Elena P Ivanova
The search for alternatives to the standard methods of preventing bacterial adhesion and biofilm formation on biotic and abiotic surfaces alike has led to the use of biomimetics to reinvent through nanofabrication methods, surfaces, whereby the nanostructured topography is directly responsible for bacterial inactivation through physico-mechanical means. Plant leaves, insect wings, and animal skin have been used to inspire the fabrication of synthetic high-aspect-ratio nanopillared surfaces, which can resist bacterial colonisation...
November 9, 2017: Nanoscale
Li-Wei Nien, Kai Chen, Thang Duy Dao, Satoshi Ishii, Chun-Hway Hsueh, Tadaaki Nagao
The optical hybridization of localized surface plasmons and photonic modes of dielectric nanostructures provides us wide arenas of opportunities for designing tunable nanophotonics with excellent spectral selectivity, signal enhancement, and light harvesting for many optical applications. Graphene-supported Au nanoprisms on a periodic Si nanopillar array will be an ideal model system for examining such an optical hybridization effect between plasmonic modes and photonic modes. Here, through the measurement of the reflectance spectra as well as graphene phonons by surface-enhanced Raman scattering (SERS), we investigated both the far-field and near-field properties of these optically hybridized modes...
November 9, 2017: Nanoscale
Keith Dusoe, Xinyi Ye, Kim Kisslinger, Aaron Stein, Seok-Woo Lee, Chang-Yong Nam
Modulus of resilience, the measure of a material's ability to store and release elastic strain energy, is critical for realizing advanced mechanical actuation technologies in micro/nanoelectromechanical systems. In general, engineering the modulus of resilience is difficult because it requires asymmetrically increasing yield strength and Young's modulus against their mutual scaling behavior. This task becomes further challenging if it needs to be carried out at the nanometer scale. Here, we demonstrate organic-inorganic hybrid composite nanopillars with one of the highest modulus of resilience per density, by utilizing vapor-phase aluminum oxide infiltration in lithographically patterned negative photoresist SU-8...
October 19, 2017: Nano Letters
Long-Hui Cui, Hyung Joon Joo, Dae Hwan Kim, Ha-Rim Seo, Jung Suk Kim, Seung-Cheol Choi, Li-Hua Huang, Ji Eun Na, I-Rang Lim, Jong-Ho Kim, Im Joo Rhyu, Soon Jun Hong, Kyu Back Lee, Do-Sun Lim
Nanotopography plays a pivotal role in the regulation of cellular responses. Nonetheless, little is known about how the gradient size of nanostructural stimuli alters the responses of endothelial progenitor cells without chemical factors. Herein, the fabrication of gradient nanopattern plates intended to mimic microenvironment nanotopography is described. The gradient nanopattern plates consist of nanopillars of increasing diameter ranges [120-200 nm (GP 120/200), 200-280 nm (GP 200/280), and 280-360 nm (GP 280/360)] that were used to screen the responses of human endothelial colony-forming cells (hECFCs)...
October 14, 2017: Acta Biomaterialia
Loïc Berthod, Olga Shavdina, Isabelle Verrier, Thomas Kämpfe, Olivier Dellea, Francis Vocanson, Maxime Bichotte, Damien Jamon, Yves Jourlin
This paper presents substantial improvements of the colloidal photolithography technique (also called microsphere lithography) with the goal of better controlling the geometry of the fabricated nano-scale structures-in this case, hexagonally arranged nanopillars-printed in a layer of directly photopatternable sol-gel TiO₂. Firstly, to increase the achievable structure height the photosensitive layer underneath the microspheres is deposited on a reflective layer instead of the usual transparent substrate. Secondly, an increased width of the pillars is achieved by tilting the incident wave and using multiple exposures or substrate rotation, additionally allowing to better control the shape of the pillar's cross section...
October 12, 2017: Nanomaterials
Sujin Baek, Su-Jin Ha, Heechul Lee, Kiwon Kim, Dongchoul Kim, Jun Hyuk Moon
The transparent characteristic of dye-sensitized solar cells (DSCs) makes them suitable for building integrated photovoltaic (BIPV) devices. However, the diffusive scattering layer, which is usually used to increase the efficiency of these devices, greatly lowers the transparency of the DSC. This paper described a two-dimensional (2D) photonic crystal (PC) reflector with a sub-micrometer characteristic length that can improve the efficiency of these devices while maintaining transparency. This 2D PCs were fabricated directly onto TiO2 photoelectrodes using colloidal lithography and have the structure of a nanopillar array...
October 12, 2017: ACS Applied Materials & Interfaces
Gil Shalev
Decorating the top surface of silicon solar cells with nanopillar arrays of subwavelength periodicity is a promising path toward low-cost thin-film photovoltaics with enhanced solar radiation absorption due to the inherent light trapping capabilities of nanopillar arrays. Common practice and knowledge for the efficient carrier extraction from the excited nanopillars is the formation of ultra-shallow radial p-n junctions that provide both short carrier collection lengths, and also ensure that the volume of the photo inactive emitter is as small as possible...
October 19, 2017: Nanoscale
R Anufriev, R Yanagisawa, M Nomura
In search of efficient thermoelectric nanostructures, many theoretical works predicted that nanopillars, placed on the surface of silicon membranes, nanobeams, or nanowires, can reduce the thermal conductivity of these nanostructures. To verify these predictions, we experimentally investigate heat conduction in suspended silicon nanobeams with periodic arrays of aluminium nanopillars. Our room temperature time-domain thermoreflectance experiments show that the nanobeams with nanopillars have 20% lower thermal conductivity as compared to pristine nanobeams...
October 12, 2017: Nanoscale
Long-Biao Huang, Wei Xu, Jianhua Hao
1D polymer nanomaterials as emerging materials, such as nanowires, nanotubes, and nanopillars, have attracted extensive attention in academia and industry. The distinctive, various, and tunable structures in the nanoscale of 1D polymer nanomaterials present nanointerfaces, high surface-to-volume ratio, and large surface area, which can improve the performance of energy devices. In this review, representative fabrication techniques of 1D polymer nanomaterials are summarized, including electrospinning, template-assisted, template-free, and inductively coupled plasma methods...
November 2017: Small
Sergey Basov, Catherine Elissalde, Quentin Simon, Mario Maglione, Christopher Castro-Chavarria, Thomas Herisson de Beauvoir, Sandrine Payan, Kristiaan Temst, Vera Lazenka, Vlad Andrei Antohe, Pedro Pereira de Sa, David Sallagoity, Luc Piraux
A new strategy to elaborate (1-3) type multiferroic nanocomposites with controlled dimensions and vertical alignment is presented. The process involves a supported nanoporous alumina layer as a template for growth of free-standing and vertically aligned CoFe2 nanopillars using a room temperature pulsed electrodeposition process. Ba0.70Sr0.30TiO3-CoFe2O4 multiferroic nanocomposites were grown through direct deposition of Ba0.7Sr0.3TiO3 films by radio-frequency sputtering on the top surface of the pillar structure, with in-situ simultaneous oxidation of CoFe2 nanopillars...
September 29, 2017: Nanotechnology
Onur Durucan, Tomas Rindzevicius, Michael Stenbæk Schmidt, Marco Matteucci, Anja Boisen
We present a simple, robust, and automated molecule extraction technique based on a centrifugal microfluidic platform. Fast and facile extraction of a food adulterant (melamine) from a complex sample medium (milk) on a SERS substrate is demonstrated. The unique characteristic of the detection method is the obtained "filter paper/chromatographic" effect which combines centrifugal force and wetting properties of the SERS substrate. The work addresses issues related to SERS-based detection of analytes in complex media, which is important for realizing next generation SERS platforms applicable for a broad variety of real-life applications...
October 27, 2017: ACS Sensors
Jon Ashley, Kaiyu Wu, Mikkel Fougt Hansen, Michael Stenbæk Schmidt, Anja Boisen, Yi Sun
There is an increasing demand for rapid, sensitive, and low cost analytical methods to routinely screen antibiotic residues in food products. Conventional detection of antibiotics involves sample preparation by liquid-liquid or solid-phase extraction, followed by analysis using liquid chromatography-mass spectrometry (LC-MS), capillary electrophoresis (CE), or gas chromatography (GC). The process is labor-intensive, time-consuming, and expensive. In this study, we developed a new analytical method that combines magnetic molecularly imprinted polymer (MMIP)-based sample preparation with surface-enhanced Raman spectroscopy (SERS)-based detection for quantitative analysis of cloxacillin in pig serum...
November 7, 2017: Analytical Chemistry
Kai Wang, Xiaoqing He, Will Linthicum, Ryan Mezan, Liying Wang, Yon Rojanasakul, Qi Wen, Yong Yang
While the rapidly evolving nanotechnology has shown promise in electronics, energy, healthcare and many other fields, there is an increasing concern about the adverse health consequences of engineered nanomaterials. To accurately evaluate the toxicity of nanomaterials, in vitro models incorporated with in vivo microenvironment characteristics are desirable. This study aims to delineate the influence of nanotopography on fibrogenic response of normal human lung fibroblasts to multi-walled carbon nanotubes (MWCNTs)...
March 1, 2017: Environmental Science. Nano
Kunping Guo, Changfeng Si, Ceng Han, Saihu Pan, Guo Chen, Yanqiong Zheng, Wenqing Zhu, Jianhua Zhang, Chang Sun, Bin Wei
Inverted organic light-emitting diodes (IOLEDs) on plastic substrates have great potential application in flexible active-matrix displays. High energy consumption, instability and poor electron injection are key issues limiting the commercialization of flexible IOLEDs. Here, we have systematically investigated the electrooptical properties of molybdenum disulfide (MoS2) and applied it in developing highly efficient and stable blue fluorescent IOLEDs. We have demonstrated that MoS2-based IOLEDs can significantly improve electron-injecting capacity...
October 5, 2017: Nanoscale
Wenyan Wang, Yanxia Cui, Kin Hung Fung, Ye Zhang, Ting Ji, Yuying Hao
Both the nanohole- and nanopillar-type patterned metallic electrodes (PMEs) have been introduced in organic solar cells (OSCs) for improving device performances experimentally, but there is few work addressing the similarities and differences between them. In this theoretical work, we systematically compare the impact of the nanohole- and nanopillar-type PMEs on the performance of an OSC based on hybridized cavity resonances. By optimizing the geometrical parameters of each PME, we obtained an interesting result that the integrated absorption efficiencies in the active layer with different optimized PMEs are almost the same (both are equal to 82...
September 19, 2017: Nanoscale Research Letters
Mian Wang, Garima Bhardwaj, Thomas J Webster
Orthopedic implant infections have been steadily increasing while, at the same time, antibiotics developed to kill such bacteria have proven less and less effective with every passing day. It is clear that new approaches that do not rely on the use of antibiotics are needed to decrease medical device infections. Inspired by cicada wing surface topographical features, nanostructured surfaces represent a new approach for imposing antibacterial properties to biomaterials without using drugs. Moreover, new chemistries with altered surface energetics may decrease bacterial attachment and growth...
2017: International Journal of Nanomedicine
Ke Du, Junjun Ding, Ishan Wathuthanthri, Chang-Hwan Choi
It is challenging to hierarchically pattern high-aspect-ratio nanostructures on microstructures using conventional lithographic techniques, where photoresist film is not able to uniformly cover on the microstructures as the aspect ratio increases. Such non-uniformity causes poor definition of nanopatterns over the microstructures. Nanostencil lithography can provide an alternative means to hierarchically construct nanostructures on microstructures via direct deposition or plasma etching through a free-standing nanoporous membrane...
September 15, 2017: Nanotechnology
Hashim Alhmoud, Anna Cifuentes-Rius, Bahman Delalat, David G Lancaster, Nicolas H Voelcker
In order to address the issue of pathogenic bacterial colonization of diabetic wounds, a more direct and robust approach is required, which relies on a physical form of bacterial destruction in addition to the conventional biochemical approach (i.e., antibiotics). Targeted bacterial destruction through the use of photothermally active nanomaterials has recently come into the spotlight as a viable approach to solving the rising problem of antibiotic resistant microorganisms. Materials with high absorption coefficients in the near-infrared (NIR) region of the electromagnetic spectrum show promise as alternative antibacterial therapeutic agents, since they preclude the development of bacterial resistance and can be activated on demand...
October 4, 2017: ACS Applied Materials & Interfaces
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