Wook-Bae Kim

Surface Finishing and Evaluation of Three-Dimensional Silicon Microchannel Using Magnetorheological Fluid

A surface-finishing method for three-dimensional microchannel structures is proposed. The method utilizes magnetorheological fluid mixed with abrasives as a polishing tool. The influences of the process parameters on the material removal were investigated, and the surface topographies before and after finishing were compared. When a microchannel was finished by proposed method, the roughness of bottom and side surfaces of the silicon channel was reduced by a factor of 5-10, and the pressure drop of a gas flow through the single microchannel was lowered to 26.7% of the pressure drop in an unfinished microchannel. The experimental results demonstrated that the proposed method was effective in finishing of microstructures.

The electromechanical principle of electrorheological fluid-assisted polishing

An up-to-date abrasive polishing process using electrorheological (ER) fluid, known as ER fluid assisted polishing, is potentially useful in the surface finish of three dimensional micro or meso-scale devices. For a more detailed understanding of this process, the electrostatic principle of how an ER fluid functions on the polishing is described. Dielectric particles suspended in a dielectric fluid are polarized with the application of an electric field, and they experience the dipolar interaction force each other and the translational force along the field, defined as dielectrophoresis due to the non-uniform electric field. As a result of the calculations of the exerted forces on the ER and abrasive particle suspended in silicone oil, ER particles strongly attract the abrasive particles as well as each other when they are aligned with the electric field. Because this attraction force is much higher than the dielectrophoretic force, abrasive particles adhere to ER particles which concentrate on a tool along the field lines. The behavior of particles is observed by the CCD camera, and borosilicate glass is polished to evaluate machining performance.

Surface polishing of three dimensional micro structures

A new polishing technique for three dimensional micro structures using magnetorheological (MR) fluid is presented. Among various fabrication technologies of micro devices, some processes such as electroplating and wet etching which are widely used, give usually rough surface. However, there has been no polishing technique useful to micro structures, while various existing polishing methods are applicable only to flat surfaces or macro scaled structures. In this study, three dimensional micro channel structures generated by copper electroplating and silicon wet etching are polished efficiently using MR fluid. As a result of polishing of both structures, the average surface roughness cuts down to more than an order with little change of original geometries and the performance of both structures is noticeably improved.

Development of apolymeric nanoactuator with its applications

T dye-sensitized solar cell (DSSC) are composed of a dye-adsorbed nanoporous TiO2 layer on a fluorine-doped tin oxide (FTO) glass substrate, redox electrolytes and a counter electrode. The heart of the system is a mesoporous TiO2 film composed of nanometer-sized particles possessing a large specific surface area. However, an unusual feature of this kind of DSSCs is the lack of the space charge layer, which separates the injected electrons from the holes in the dye or electrolyte. A unidirectional charge flow with no electron leakage at the interfaces is essential for high energy-conversion efficiency. In this paper, DSSC were constructed by application of Fe2O3 and TiO2 nanoparticle/TiO2 nanotube (TNT) composite particles with various percentages. The use of oxide semiconductors in the form of nanorod, nanowires and nanotubes may be an interesting approach to improve electron transport through the film. In addition suitable amount of TNT in the film could provide large surface area for the adsorption of the dye. The Fe2O3-doped reduced the surface trap states of TiO2 suppressed the charge recombination, and increased the driving force of electron injection, thereby improved its power conversion efficiency. The impedance results indicate improved electron transport at the TiO2/dye/electrolyte interface. This result is attributed to the prevention of electron recombination between electrons in the TiO2 conduction band with dye or electrolytes. TiO2 passivating layer was deposited on the substrate by hydrolysis of TiCl4 aqueous solution. TiO2 layer was coated on FTO glass by doctor blade method. The dye-sensitized solar cells were fabricated using dye of ruthenium (II)(N719) and electrolyte (I-/I3-)The DSSC based on Fe2O3/TiO2/TNT composite particles hybrids showed a better photovoltaic performance than the cell purely made of TiO2 nanoparticles. The crystalline structure and morphology were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The absorption spectra were measured by UV-vis spectrometer. The conversion efficiency was measured by solar simulator (100 mW/cm2). Hyung Wook Choi et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014695 ©2014 Society for BiomaterialsP ZnS nanoparticles were precipitated by heterogeneous nucleation on the surface of carrying silicon nanoparticles, dispersed in an aqueous solution of zinc acetate with sodium sulphide. The produced photoactive colloidal dispersion was desiccated in two different ways. 1. The dispersion was filtered and the residual water evaporated in the presence of air at 100°C. 2. The aqueous dispersion was very rapidly freezed to -20°C and water molecules sublimated at the required optimal rate in the controlled vacuum. The structure of the composite material (Si)ZnS produced via thermal drying at 100°C is significantly tighter than the structure obtained by vacuum freeze-drying. Controlled freeze-drying enables self-organization of composite nanoparticles into lamellar structures, as shown in Figure 1, with a significantly larger specific surface area than the product of ordinary thermal drying. It thus provides several times higher catalytic efficiency.T purpose of this study was to develop and optimize the Solid Lipid Nanoparticles of the Asenapine maleate, an antipsychotic drug using Artificial Neural Networks-Genetic Algorithm (ANN-GA) technique. Naoparticles were prepared by the high shear homogenization/sonication technique. A set of experiments was carried out to evaluate the effect of composition (drug/lipid ratio and surfactant concentration) and process variable (homogenization and sonication time) for the preparation of nanoparticles. The experimental data of 31 trials were designed using central composite design (CCD). Data were divided into two sets: training and test data set. A feed forward back propagation (FFBP) model of ANN was constructed and its input space was optimized using a genetic algorithm (GA) program. The ANN consisted of three levels of neurons: an input layer, a hidden layer and an output layer. The output results were observed in the form of particle size, polydispersity index and entrapment efficiency. The obtained result shows a correlation coefficient (r2) value of 0.97 and a root-mean-square error of 0.21 for the calculated/predicted properties with respect to experimental values, demonstrating the reliability of the proposed model. Therefore, ANN-GA represents a novel tool for optimization of composition, process variables and their predicted outcomes in development of solid lipid nanoparticles. Sanjay Kumar Singh et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014S the first realization of capacitor in 1745 followed by conceptualization of resistor and inductor in 1827 and 1831 respectively, the design community has been limited to these three fundamental passive circuit elements. Memristor and memristive constructs at nanoscale have emerged over the last few years through a combination Metal-Insulator-Metal (MIM) processing technology; thus paving the way for an efficient adoption of memristor constructs such as ReRAM crossbar-based architectures. However, a noticeable drawback of the crossbar architecture that remembers to be solved is the existence of sneakpaths between adjacent cells. This work presents a novel approach in implementation of complementary resistive switch based on transparent memristors. The upper TiO2-x layer was deposited by atomic layer deposition using titanium tetra-isopropoxide and O2 as the precursor and the oxygen source respectively; with oxygen deficiency of 5%. The lower TiO2 is 4 nm thick while the upper TiO2-x layer is 12 nm thick. The fabricated MIM structure has shown promising results in terms of functional reproducibility and high speed switching for digital and low-voltage analog application.R there are huge demands for nanoscale actuation and positioning with the rapid progress of nanotechnology. Nanoactuationbased on piezoelectricity is one of the most popular methods for nanoactuation. Flexure mechanism have been introduced as one of the most effective methods to guide nanometer-scale motion to the desired motion mode. As a result, various types of nanoactuators using both piezoelectric actuator and flexure mechanismareapplied to a great variety of applications. However, typical materials for flexure mechanism is metal and it is machined using wire-cut electrical discharge machining to ensure manufacturing accuracy. Therefore, careful consideration needs to be made to avoid corrosion and circumference interference. Here, we presented a chip-like polymeric nanoactuatorbased on a flexure mechanism and piezoelectric actuation. Motion specification and injection moldability were expected using FEM softwaresin its design stage to achieve higher motion accuracy and avoid parasitic motion. The material for the actuator was a cyclic olefin copolymer (COC), which provided superior mechanical and optical properties and biocompatibility than other polymers.The nanoactuator was fabricated using mesoscale injection molding, then it was equipped with piezoelectric stack actuation, capacitive displacement sensor and a PID controller for experimental verification. From the experiments it could be demonstrated that the nanoactuator had a travel range of 15 microns and control error was less than 3 nm. The developed nanoactuator is being applied to optical alignment and microbioreactor for cell biology. Acknowledgement: This work was supported by the Platform Technology Development program of the Ministry of Trade, Industry and Energy, Republic of Korea. Young Hun Jeong et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014H of millions of adults have high cholesterol, which has generated a billionaire market of drugs (mainly statin-based drugs) devised to reduce and control the total serum cholesterol levels. Patents covering the leading statins have expired recently, which pressures the development of new drugs for the market. Statins act by inhibiting the 3-hydroxy-3-methylglutaryl coenzyme (HMG-CoA) reductase in the process of converting HMG-CoA, a committed step in the biosynthesis of cholesterol. In this work, we take full advantage of the published crystallographic data of HMGR complexed with statins to perform computer simulations within an ab-initio quantum mechanical approach, based on the density functional theory (DFT) and in the framework of the molecular fractionation with conjugate caps (MFCC) strategy, to investigate the details of the binding interaction of the statins atorvastatin (A, PDB ID 1HWK), rosuvastatin (R, 1HWL), fluvastatin (F, 1HWI), cerivastatin (C, 1HWJ), mevastatin (M, 1HW8), and simvastatin (S, 1HW9) to the HMGR enzyme. The purpose is to elucidate why statins have differences in their efficiency to reduce cholesterol levels by obtaining and comparing the interaction energy between the HMGR residues and the ligand atoms. The main advantage of the methodology we propose here is the possibility to evaluate which amino acid residues contribute more intensely to the stabilization of the statin-HMGR complex, which canbe very helpful for purposes of drug design and delivery. E. L. Albuquerque et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014M tuberculosis AHAS is a potential and promising candidate in the development of novel anti-tuberculosis drugs. Acetohydroxyacid synthase (AHAS) from M. tuberculosis is one of the biosynthetic enzymes, which catalyzes the first common step in the biosynthesis of the essential branched chain amino acids (BCAA’s: valine, leucine, and isoleucine). Aptamers are single-stranded nucleic acid molecules that can fold into complex three-dimensional shapes, forming binding pockets and clefts for the specific recognition and tight binding of any given molecular target, from metal ions and small chemicals to large proteins and higher order protein complexes, whole cells, viruses, or parasites. Aptamers are selected by in vitro process known as systematic evolution of ligands by exponential enrichment (SELEX). In this study, an in vitro selection method, SELEX, was used to find single-stranded DNA aptamer towards M. tuberculosis AHAS. We found twelve ssDNA aptamers against M. tuberculosis AHAS through in vitro selection by SELEX. Among these aptamers, 3 aptamers of the biotinylated modified demonstrated higher binding affinity determined by aptamer-based ELISA method. One of the aptamer showed inhibitory action against M. tuberculosis AHAS. This study would further be useful in discovering and producing novel class of aptamer-based inhibitors. Moon-Young Yoon, J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014N catalysts have multiple industrial applications. Recent focus has been on their clean manufacture and biofabrication. Biofabricated nano-scale palladium (bio-Pd) is active in the reductive dehalogenation (hydrogenolysis) of chlorinated aromatic compounds. Bio-Pd catalyst is made via biosorption of Pd (II) and its subsequent reduction to Pd (0) to give bio-scaffolded Pd-nanoparticles on bacterial cell surfaces. Gram negative cells (e.g. Desulfovibrio desulfuricans) and gram positive cells (e.g. Bacillus spp.) made bio-Pd comparably active in hydrogenation reactions but have not been compared with respect to hydrogenolysis and dechlorination of chlorinated aromatic compounds. Bio-Pd (0) by D. desulfuricans and Bacillus benzeovorans were prepared and compared with respect to their patterning on bacteria. The Pd-nanoparticle sizes were measured via X-ray powder diffraction via data analysed using Scherrer’s equation which indicated a significant difference in particle size. The bioPd catalysts were evaluated with respect to their differing abilities in the dehalogenation of chlorobenzene; both showed higher catalytic activity than commercial palladium on carbon (Pd/C) catalyst. Jacob B. Omajali et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014N derived from a Group of Uniform Materials Based on Organic Salts (NanoGUMBOS) have unique and versatile properties derived from ionic liquids. These organic nanoparticles display enhanced and uniform properties at the nanoscale level. NanoGUMBOS, with melting points between 25°C and 250°C, are useful for various applications depending on the type of anion and cation used for formation. The performance and reliability of these applications are often size-dependent because the properties of nanoparticles often change with size and stacking arrangement due to electron confinement into small spaces. Therefore, my research has focused on controlling the size of nanoGUMBOS that are composed of imidazolium based organic salts. In this talk, I will discuss non-templated ultrasonication and microwave-based synthesis methods. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential measurements (ζ measurements) were used to study the size and stability of nanoparticles in aqueous medium. Spectrophotometric measurements were also useful for investigating structural effects related to decreases in size of nanoparticles. Furthermore, the behavior of nanoGUMBOS formation under microwave heating was explained by observing their dielectric properties. As result of this study, I was able to reduce the size of zero-dimensional particles derived from GUMBOS to nanoscale and understand their behavior by use of various characterization techniques. Suzana Hamdan et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014T intensification of infrared-active vibrational modes of molecules in close proximity to nanometer-thick metal films, commonly known as surface-enhanced infrared absorption (SEIRA), is receiving increased attention from both a phenomenological and practical viewpoint. The resonant excitation of plasmon in metallic nanostructures can provide large field enhancements on the surfaces of metals, which in turn provide dramatic increases in the detected spectroscopic signals for molecules adsorbed on their surfaces. The most widely used surface enhanced spectroscopy (SES) is surface enhanced Raman scattering (SERS), where the electromagnetic enhancement factor is proportional to the fourth power of the field incident on the molecule. Recently there has been a resurgence of interest in another type of SES, surface enhanced infrared absorption. It has been widely applied to surface trace analysis, bio-sensing, electro sorption, and electro catalysis because of its significant amplification of surface signal and simple surface selection rule. The surface enhanced infrared absorption can be observed easily on metal island films prepared by vacuum evaporation or sputtering and electrochemical or electroless deposition. Metal colloids also support the enhancement. Like surface-enhanced Raman scattering (SERS), SEIRA is chiefly of electromagnetic origin, that is, due to an increase in the local optical field exciting the adjacent molecule. Metal nano clusters much smaller than the wavelength of light facilitate the interaction of the infrared radiation with the metal and adsorbed molecules, resulting in the enhancement. It was explained that the enhancement is greatly affected by the size, and planer density of metal nano clusters compared with metal nano films. Phenomenological and theoretical difference of infrared absorption in broad ranges of wave length including near field to far field infrared rays between metal nano clusters and metal nano films. Especially, metal nano clusters exhibit much higher infrared absorption than metal nano films on broad ranges of wave length. The phenomenon of infrared absorption in the range of near infrared wave length was different from that of far infrared wave length. This different phenomenon involves shift of resonant peaks and absorption intensities on them. Also the planar density of the metal nano clusters suggests a mechanism to explain the phenomenon. Jae Hong Park et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014B chemical composition is mainly carbon, which is considered a primary source for the manufacture of functional carbon materials. The high carbon composition of biomass attracted scientists’ attention as a standpoint to solve economic and environmental issues. The aim of this work is to obtain carbon nanostructures using a pyrolysis process followed by a chemical vapor deposition (CVD) (called from here pyrolysis vapor deposition). Pyrolytic carbon from nutshell was obtained at 450oC with a 0.75 h of residence time. Deposit nanoparticle morphologies were obtained with respect to the location in the downstream part of the reactor. At L1 position, carbon deposit groups in layers with a composition of 98.3% carbon and 1.7% oxygen. Carbon deposit at position L2 presented a semispherical conformation with a carbon composition between 98.3-100% by weight. Carbon deposit at position L3, shows a formation of carbon and iron nanobelts, as well as semispherical sintered nanoparticles, which corresponds to carbon and inorganics detected during tests. All These results support the statement that it is possible to achieve several carbon nanoparticles deposition morphologies from biomass pyrocarbon. Synthesis of carbon nanostructures from biomass by pyrolysis vapor deposition is possible but is still is early stages of development. A throughout study of pyrolysis conditions, biomass source, kinetics, morphologies and chemistry must be done in order to refine the synthesis and be able to have high quality an quantity of carbon nanostructures. Eileen Carrillo Pedraza, J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014H polymeric capsules of nanometer to micrometer dimensions have been endowed with variety of applications. They can be used for drug and gene delivery, as microreactor and as templates for inorganic and organic nanoparticles. We present here polymer bound hollow capsules that are capable to fish gold nanoparticles within a certain size range and encapsulate other precious metal nanoparticles. Polymer bound hollow capsules of a sulfur containing polymer were prepared by dissolving gold core of an analog gold nanoparticle containing hybrid material, which was prepared by free radical copolymerization of methyl methacrylate and mono-functionalized gold nanoparticle with vinyl group as artificial monomer. The size exclusive fishing of gold nanoparticles has been carried out by using simple ligand exchange reaction. Citrate stabilized gold nanoparticles of different sizes ranging from 56 nm to 4 nm in the aqueous phase were used as “fish”. Successful fishing process was proven by UVVis spectroscopy and transmission electron microscopy (TEM). The hollow capsules can encapsulate gold nanoparticles under 15 nm effectively. When a mixture of citrate stabilized gold nanoparticle in different sizes was used as “fish”, the hollow capsules caught more small “fish” (3 nm) than large “fish” (15 nm) and the oversize “fish” was excluded. The hollow capsules can also act as universal carrier for precious metal nanoparticles. Silver, palladium, platinum nanoparticles have been successfully refilled in the hollow capsules via in-situ reduction route, which have promising future in the field of catalysis. Ziyin Fan et al., J Nanomed Nanotechnol 2013, 4:6 http://dx.doi.org/10.4172/2157-7439.S1.014

Surface Smoothing of Blasted Glass Micro-Channels Using Abrasive Waterjet

Powder blasting, which is an efficient micromachining method for glass, silicon, and ceramics, has a critical disadvantage in that the surface finish is poor owing to the brittle fracture of materials. Low-pressure waterjet machining can be applied to smoothen the rough surface inside the blasted structure. In this study, the surface roughness and sectional dimension of micro-channels are observed during the repetitive application of a waterjet to blasted micro-channels. The asperities and subsurface cracks created by blasting are removed by waterjet machining. Along with the surface roughness, it is found that the sectional dimension increases and the edges of the finished micro- channel become slightly round. Finally, a microfluidic chip is machined by the blasting-waterjet process and a transparent microfluidic channel is obtained efficiently.