Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session T15: Nanotechnology |
Hide Abstracts |
Sponsoring Units: FIAP Chair: Samir Iqbal, University of Texas at Arlington Room: 008B |
Thursday, March 5, 2015 11:15AM - 11:27AM |
T15.00001: Structural aspects of TiO$_{2}$ nanopowders Sergey Mamedov TiO$_{2}$ nanopowders obtained using different methods with the mean size of 5, 15, 30 and 40 nm have been investigated by Raman spectroscopy in wide spectral range. Nano-size of TiO$_{2}$ crystals lead to a shift and broadening of the first-order Raman lines through a relaxation of the q $=$ 0 selection rule and effects on to the position, width and asymmetry of a Raman bands. The details of the evolution of the 144 cm$^{-1}$ Raman line shape on the size and distributions of the nanopowders are presented and discussed in frame of confined phonons model. Analysis of Raman spectra shows that structural characteristics of nanopowders may be different even size of the nanopowders is the same. Structural features of the material depend on preparation methods/conditions and can be extracted from Raman spectra of the material. [Preview Abstract] |
Thursday, March 5, 2015 11:27AM - 11:39AM |
T15.00002: Growth and Characterization of Coherently Strained Si-Si$_{x}$Ge$_{1-x}$ Core-Shell Nanowire Heterostructures David Dillen, Kyounghwan Kim, Emanuel Tutuc The large valence band offset in Ge-Si$_{x}$Ge$_{1-x}$ core-shell nanowires has provided an interesting platform for the study of quasi one-dimensional hole-confined systems, and has led to the demonstration of high-performance electronic devices. Progress in the development of electron-confined systems using Group-IV core-shell structures has, however, been much slower. Coherently strained Si-Si$_{x}$Ge$_{1-x}$ core-shell nanowires represent one possible radial heterostructure where a positive shell-to-core conduction band offset, beneficial for quantum confinement of electrons in the Si core, may be realized. We discuss the growth of strained Si-Si$_{x}$Ge$_{1-x}$ core-shell nanowires with tunable shell composition using vapor-liquid-solid growth for the Si nanowire core, followed \textit{in-situ} by Si$_{x}$Ge$_{1-x}$ shell growth. Transmission electron microscopy reveals a single crystal nanowire structure, evincing an epitaxial shell growth. Raman spectroscopy reveals a red-shift of the core Si-Si Raman mode, which depends on the shell composition and nanowire thickness, indicating coherent tensile strain in the Si core. [Preview Abstract] |
Thursday, March 5, 2015 11:39AM - 11:51AM |
T15.00003: Gold Nanorod translocations and charge measurement through solid-state nano pores Rebecca Engelke, Mehdi Zanjani, Kim Venta, Xingchen Ye, Gopinath Danda, Christopher Murray, Jennifer Lukes, Marija Drndic We study translocations of gold nanorods through silicon nitride nanopores and present a method for determining the surface charge of nanorods from the magnitude of the ionic current change as nanorods pass through the pore. Positively-charged nanorods with average diameters 10 nm and average nanorod lengths between 44 and 65 nm were translocated through 40 nm thick nanopores with diameters between 19 and 27 nm in 1, 10, or 100 mM KCl solutions. The presented method based on comparing simulations with experiments predicts a surface charge of 26 mC/m$^2$ for 44 nm long gold nanorods and 18 mC/m$^2$ for 65 nm long gold nanorods. [Preview Abstract] |
Thursday, March 5, 2015 11:51AM - 12:03PM |
T15.00004: The Effects of Nanotexturing Microfluidic Platforms to Isolate Brain Tumor Cells Muhymin Islam, Adeel Sajid, Young-Tae Kim, Samir M. Iqbal Detection of tumor cells in the early stages of disease requires sensitive and selective approaches. Nanotextured polydimethylsiloxane (PDMS) substrates were implemented to detect metastatic human glioblastoma (hGBM) cells. RNA aptamers that were specific to epidermal growth factor receptors (EGFR) were used to functionalize the substrates. EGFR is known to be overexpressed on many cancer cells including hGBM. Nanotextured PDMS was prepared by micro reactive ion etching. PDMS surfaces became hydrophilic uponnanotexturing. Nanotextured substrates were incubated in tumor cell solution and density of captured cells was determined. Nanotextured PDMS provided \textgreater 300{\%} cell capture compared to plain PDMS due to increased effective surface area of roughened substrates at nanoscale as well as mire focal points for cell adhesion. Next, aptamer functionalized nanotextured PDMS was incorporated in microfluidic device to detect tumor cells at different flow velocities. The shear stress introduced by the flow pressure and heterogeneity of the EGFR overexpression on cell membranes of the tumor cells had significant impact on the cell capture efficiency of aptamer anchored nanotextured microfluidic devices. Eventually tumor cells were detected from the mixture of white blood cells at an efficiency of 73{\%} using the microfluidic device. The interplay of binding energies and surface energies was major factor in this system. [Preview Abstract] |
Thursday, March 5, 2015 12:03PM - 12:15PM |
T15.00005: Nano-Storage Wires for the Controlled Release of Biochemical Materials Haneul Yoo, Dongjun Lee, Eunji Kim, Daesan Kim, Juhun Park, Seunghun Hong We herein report ``nano-storage wires'' (NSWs) that can store chemical species and release them at a desired moment by electrical stimulations. Here, we utilized the electrodeposition process through an anodized aluminium oxide template to fabricate multi-segmented nanowires which consisted of a polypyrrole (PPy) segment containing adenosine triphosphate (ATP) molecules, a ferromagnetic nickel segment, and a conductive gold segment. We could drive and deposit the NSWs onto desired positions on electrode surfaces via external magnetic fields. When the external electric potential was applied from the electrodes, the NSWs released ATPs from the PPy segments, and the released ATPs could change the activities of motor proteins near the NSWs. Furthermore, through direct writing or magnetic manipulation strategies, we could print NSWs onto various substrates such as flexible or three-dimensional structured substrates to build versatile chemical storage devices. Since our strategy enables the controllable storage and release of chemicals, our development should open up various applications such as drug delivery systems, biosensors and biochips for the controlled release of chemicals to biosystems. [Preview Abstract] |
Thursday, March 5, 2015 12:15PM - 12:27PM |
T15.00006: Precise Fabrication of Nanopores with Diameters of Sub-1 nm to 3 nm Using Multilevel Pulse-voltage Injection Itaru Yanagi, Rena Akahori, Takahide Yokoi, Ken-ichi Takeda To date, solid-state nanopores have been fabricated primarily through a focused-electronic beam via TEM. For mass production, however, a TEM beam is not suitable and an alternative fabrication method is required. Recently, a simple nanopore-fabrication method has been reported that is based on a dielectric breakdown phenomenon of a thin membrane. In this study, to stably fabricate nanopores with diameters of 1 to 2 nm (which is an essential size for distinguishing each nucleotide) via dielectric breakdown, a technique called multilevel pulse-voltage injection (MPVI) is proposed and demonstrated. MPVI uses pulse voltages for generating the nanopores, and the generation of the nanopores is verified by measuring the current through a membrane at low voltage. This method can generate nanopores with diameters of less than 1 nm in a 10-nm-thick Si$_{3}$N$_{4}$ membrane with a probability of 90{\%}. The diameter of the generated nanopores can be widened to the desired diameters (up to 3 nm) with sub-nanometre precision. The mean effective thickness of the fabricated nanopores was 3.7 nm. These findings are derived from TEM images of the fabricated nanopores and analyses of ionic-current blockades during single-stranded DNA translocation. [Preview Abstract] |
Thursday, March 5, 2015 12:27PM - 12:39PM |
T15.00007: Electrospraying in a complex electrical field: jet formation and characteristics of final product Sheila Khodadadi, Kirsten Rovers, Gabriel Meesters The electrohydrodynamic atomization (EDHA) of liquid solutions is a technique developed to produce micro and nanometer size droplets. It consists of breaking a liquid jet by applying electrical forces. EHDA is one of the most suitable techniques for drug delivery and bio-nanotechnology, when precise (nm-$\mu$m) particle size and narrow size distribution is needed. However there are some challenges facing application of this technique such as limitation in flow rate, characteristics of liquids (surface tension, conductivity,\textellipsis ), and the possible droplet size reduction due to evaporation of the liquid and Coulomb fission. To tackle these challenges in an EHDA-based inhalation device, we explored different possibilities to reach a stable mode in terms of jet formations, droplet-particle size and size distribution. In this contribution, we demonstrate how device configuration and operational conditions influence the electrosprayed liquid and final product. We will also discuss how our approach can be used to tailor morphological properties of nanostructured materials with identical chemical compositions. [Preview Abstract] |
Thursday, March 5, 2015 12:39PM - 12:51PM |
T15.00008: Effect of processing temperature on the properties of Fe-Hydroxyapatite Vindu Kathriarachchi, Theodora Leventouri, Adam Rondinone, Korey Sorge Multi-substituted Hydroxyapatite (HAp), Ca$_{5}$(PO$_{4}$)$_{3}$OH, is the main mineral phase in physiological apatite. Fe is a minor substitution element in bone and enamel substituting Ca in the HAp structure. Crystal structure, magnetic and microstructure properties of Ca$_{\mathrm{5-x}}$Fe$_{\mathrm{x}}$(PO$_{4}$)$_{3}$OH depend on processing parameters. We present results from our research on the Ca$_{\mathrm{5-x}}$Fe$_{\mathrm{x}}$(PO$_{4}$)$_{3}$OH system ($x =$ 0.0, 0.05, 0.1, 0.2 and 0.3) prepared at 37$^{\circ}$ C, and 80$^{\circ}$ C. Hydroxyapatite single-phase was detected for $x$ \textless 0.1 in both sets of samples, while hematite and/or maghemite develops starting at $x =$ 0.1. Rietveld refinements of XRD and NPD patterns show that the $a$ and $c$ lattice constants decrease with increasing Fe concentration for both sets of samples. Pure HAp is diamagnetic but as $x$ increases, Fe-HAp transitions from paramagnetic to weak ferromagnetic behavior. TEM images show spherical particles in samples prepared at 37$^{\circ}$ C, and elongated particles in samples prepared at 80$^{\circ}$ C. XRF studies confirm the iron substitution and show that the Ca/P stoichiometric ratio of 1.67 decreases with increasing the Fe concentration. Further, the Fe/Ca$+$Fe atomic ratios of samples prepared at 37$^{\circ}$ C are greater than those prepared at 80$^{\circ}$ C. [Preview Abstract] |
Thursday, March 5, 2015 12:51PM - 1:03PM |
T15.00009: Application of near infrared sensitive multifunctional nanophosphors in optical and photoacoustic imaging Francisco Pedraza, Ajith Kumar, Lawrence Mimun, Jing Yong Ye, Dhiraj Sardar Though there are several contrast agents available in the biomedical industry for non-invasive imaging, many of them are not capable of providing in-depth information with high signal to noise ratio. Because of the extremely high scattering processes in the biological medium, most of the optical imaging techniques fail to provide sufficient resolution in deep tissue. An alternate way to circumvent this difficulty is to integrate multiple imaging modalities such as optical, magnetic, and photoacoustic (PA) in a single contrast agent. Trivalent rare earth doped inorganic nanophosphors are found to be the most suitable candidates for this purpose due to their excellent NIR spectral properties. In addition, by controlling the non-radiative processes through various emission channels, it is possible to generate strong PA signals that would help us explore the wavelength dependent PA imaging features. Furthermore, magnetic imaging can be added by incorporating paramagnetic (Gd) or ferromagnetic (Fe) ions suitable lattice positions. In this work we explore the NIR sensitive optical and PA imaging features of rare-earth doped phosphors and compare their capabilities with other metallic nanoparticle-based PA imaging agents. [Preview Abstract] |
Thursday, March 5, 2015 1:03PM - 1:15PM |
T15.00010: Fabricating quench condensed lead thin film circuits using MEMS Fab on a Chip technology Matthias Imboden, Han Han, Pablo del Corro, Flavio Pardo, Cristian Bolle, David Bishop We have developed a MEMS Fab on a Chip consisting of micro-sources, mass sensors, heaters/thermometers, shutters and a dynamic stencil. The fab only occupies a volume of a few cubic millimeters and consumes milliwatts of power, and hence can be operated in a cryostat. Thin film patterns of arbitrary shapes using multiple materials can be manufactured, while strongly suppressing thermal annealing effects. We demonstrate deposition of quench condensed lead films with fractions of a monolayer thickness control. Furthermore, using low deposition rates it is estimated that the surface temperature of the target heats by only 1.7 K. We study the effects of growing quench condensed films with different evaporation rates to demonstrate thermal annealing effects which occur during deposition. We measure the minimum conduction thickness (insulator to metal transition) as well as the superconducting transition temperature as a function of film thickness in order to shed light on growth of amorphous films and the transition to nanocluster formations. The Fab on a Chip will allow us to build nanocircuits made of ultra-thin materials. Annealing and doping is controlled and measurements occur in situ, without exposing the fabricated circuits to thermal fluctuations or foreign contaminants. This enables new types of experiments based on quantum circuits which cannot be fabricated using standard lithography techniques. [Preview Abstract] |
Thursday, March 5, 2015 1:15PM - 1:27PM |
T15.00011: High speed electrical measurement for roll-to-roll nanomanufacturing Nathan Orloff, Christian Long, Jan Obrzut, Laurent Maillaud, Francesca Mirri, Thomas Kole, Robert McMichael, Matteo Pasquali, Stephan Stranick, J. Alexander Liddle Roll-to-roll processing of nanomaterials can produce high-quality coatings and filaments continuously, enabling materials applications for electronics, fabrics, and wires. These applications often require specific electrical properties that are correlated to the material's nanostructure. While several high-throughput structural characterizations techniques exist, there are relatively few contactless options for quantifying the electrical properties of materials for nanomanufacturing. Here, we demonstrate a microwave method for measuring complex permittivity (or geometry for samples of known dielectric properties) in a millisecond. The demonstrated measurement times are suitable for current industrial needs, allowing real-time materials characterization and in-line control of processing variables without disrupting production. [Preview Abstract] |
Thursday, March 5, 2015 1:27PM - 1:39PM |
T15.00012: Development Characteristics of PMMA in alternative alcohol:water mixtures Leonidas E. Ocola The most widely used resist in electron beam lithography is polymethylmethacrylate (PMMA). The standard developers used are solution mixtures of isopropanol (IPA) and methyl isobutyl ketone (MIBK) in a ratio of 3:1 and mixtures of IPA and water (H2O) in a ratio of 7:3. The Globally Harmonized System (GHS) classification entry for IPA includes: Specific target organ toxicity - single exposure (Category 3). MIBK is much more hazardous than IPA. The only GHS classification entry for Ethanol is: Flammable liquids (Category 2), i.e. more environmentally safe. Using Ethanol/H2O as a developer will therefore enable lower hazardous waste disposal costs to cleanrooms. We find Ethanol/H2O at 85{\%} volume (2:1 molar) exhibits excellent lithography results as good as with IPA/H2O, and better contrast and sensitivity than IPA/H2O and MIBK/IPA developers. Lithographic data shows trends similar to published cosolvency data, but differ too much to be explained by it. In addition, unusual development at 50{\%} volume concentrations for both IPA and Ethanol in H2O show dramatic pothole formation instead of uniform thickness loss found in standard contrast curve exposures. We believe local pockets of concentrated alcohol water molar mixtures are responsible for such behavior. [Preview Abstract] |
Thursday, March 5, 2015 1:39PM - 1:51PM |
T15.00013: ABSTRACT WITHDRAWN |
Thursday, March 5, 2015 1:51PM - 2:03PM |
T15.00014: Reaching the Ionic Current Detection Limit in Silicon-Based Nanopores Matthew Puster, Julio Alejandro Rodriguez-Manzo, Adrien Nicolai, Vincent Meunier, Marija Drndic Solid-state nanopores act as single-molecule sensors whereby passage of an individual molecule in aqueous electrolyte through a nanopore is registered as a change in ionic conductance ($\Delta $G). Future nanopore applications such as DNA sequencing at high bandwidth require high $\Delta $G for optimal signal-to-noise ratio. Reducing the nanopore diameter and thickness increase $\Delta $G. Molecule size limits the diameter, thus efforts concentrate on minimizing the thickness by thinning oxide/nitride films or using 2D materials. Weighted by electrolyte conductivity the highest $\Delta $G reported to date for DNA translocations were obtained with nanopores made in oxide/nitride films. We present a controlled electron irradiation technique to thin such films to the limit of their stability, producing nanopores tailored to molecule size in amorphous Si with thicknesses less than 2 nm. We compare $\Delta $G values with results found in the literature for DNA translocation through these nanopores, where access resistance becomes comparable to the resistance through the nanopore itself. [Preview Abstract] |
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