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Articles 91 - 113 of 113

Full-Text Articles in Nanoscience and Nanotechnology

Scalable Nanotemplate Assisted Directed Assembly Of Single Walled Carbon Nanotubes For Nanoscale Devices, Prashanth Makaram, Sivasubramanian Somu, Xugang Xiong, Ahmed A. Busnaina, Yung-Joon Jung, Nicol E. Mcgruer May 2011

Scalable Nanotemplate Assisted Directed Assembly Of Single Walled Carbon Nanotubes For Nanoscale Devices, Prashanth Makaram, Sivasubramanian Somu, Xugang Xiong, Ahmed A. Busnaina, Yung-Joon Jung, Nicol E. Mcgruer

Yung Joon Jung

The authors demonstrate precise alignment and controlled assembly of single wall nanotube (SWNT) bundles at a fast rate over large areas by combining electrophoresis and dip coating processes. SWNTs in solution are assembled on prepatterned features that are 80 nm wide and separated by 200 nm. The results show that the direction of substrate withdrawal significantly affects the orientation and alignment of the assembled SWNT bundles. I-V characterization is carried out to demonstrate electrical continuity of these assembled SWNT bundles.


Mechanical And Electrical Evaluation Of Parylene-C Encapsulated Carbon Nanotube Networks On A Flexible Substrate, Chia-Ling Chen, Ernesto Lopez, Yung-Joon Jung, Sinan Müftü, Selvapraba Selvarasah, Mehmet R. Dokmeci May 2011

Mechanical And Electrical Evaluation Of Parylene-C Encapsulated Carbon Nanotube Networks On A Flexible Substrate, Chia-Ling Chen, Ernesto Lopez, Yung-Joon Jung, Sinan Müftü, Selvapraba Selvarasah, Mehmet R. Dokmeci

Mehmet R. Dokmeci

Carbon nanotube networks are an emerging conductive nanomaterial with applications including thin film transistors, interconnects, and sensors. In this letter, we demonstrate the fabrication of single-walled carbon nanotube (SWNT) networks on a flexible polymer substrate and then provide encapsulation utilizing a thin parylene-C layer. The encapsulated SWNT network was subjected to tensile tests while its electrical resistance was monitored. Tests showed a linear-elastic response up to a strain value of 2.8% and nearly linear change in electrical resistance in the 0%–2% strain range. The networks’ electrical resistance was monitored during load-unload tests of up to 100 cycles and ...


Directed Assembly Of Gold Nanoparticle Nanowires And Networks For Nanodevices, Xugang Xiong, Ahmed A. Busnaina, Selvapraba Selvarasah, Sivasubramanian Somu, Ming Wei, Joey Mead, Chia-Ling Chen, Juan Aceros, Prashanth Makaram, Mehmet R. Dokmeci May 2011

Directed Assembly Of Gold Nanoparticle Nanowires And Networks For Nanodevices, Xugang Xiong, Ahmed A. Busnaina, Selvapraba Selvarasah, Sivasubramanian Somu, Ming Wei, Joey Mead, Chia-Ling Chen, Juan Aceros, Prashanth Makaram, Mehmet R. Dokmeci

Mehmet R. Dokmeci

Alternating electric field is used to assemble gold nanoparticle nanowires from liquid suspensions. The effects of electrode geometry and the dielectrophoresis force on the chaining and branching of nanowire formation are investigated. The nanowire assembly processes are modeled using finite element calculations, and the particle trajectories under the combined influence of dielectrophoresis force and viscous drag are simulated. Nanoparticle nanowires with 10 nm resolution are fabricated. The wires can be further oriented along an externally introduced flow. This work provides an approach towards rapid assembly and organization of ultrasmall nanoparticle networks.


Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier F. Casse, Ravinder K. Banyal, W. T. Lu, Y. J. Huang, Selvapraba Selvarasah, Mehmet R. Dokmeci, Srinivas Sridhar May 2011

Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier F. Casse, Ravinder K. Banyal, W. T. Lu, Y. J. Huang, Selvapraba Selvarasah, Mehmet R. Dokmeci, Srinivas Sridhar

Mehmet R. Dokmeci

We show that a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction, thereby expanding the range of optical properties theoretically available for future optoelectronic devices. The mechanism for achieving a negative-index lens is based on exploiting the periodicity of the surface corrugation. By designing and nanofabricating a planoconcave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 μm that such negative-index concave lenses can focus plane waves. The beam propagation in the lens was studied experimentally and was in excellent agreement with the three-dimensional finite-difference time-domain numerical simulations.


Nanoinformatics 2010: Community-Wide Collaboration For The Collection, Curation, Analysis, And Dissemination Of Nanotechnology Data, Rebecca C. Reznik-Zellen, Mark Tuominen, Jeff Morse, Robert Stevens May 2011

Nanoinformatics 2010: Community-Wide Collaboration For The Collection, Curation, Analysis, And Dissemination Of Nanotechnology Data, Rebecca C. Reznik-Zellen, Mark Tuominen, Jeff Morse, Robert Stevens

Rebecca C. Reznik-Zellen

Objective: To describe the emerging disciplinary community of Nanoinformatics, of which the University of Massachusetts Amherst is a part, and Nanoinformatics 2010, a collaborative roadmapping workshop organized by this community to coordinate the existing but diverse efforts to collect, curate, analyze, and disseminate nanotechnology data.

Participants: InterNano1 and the National Nanomanufacturing Network2—funded by the National Science Foundation Center for Hierarchical Manufacturing3 and administered by the University of Massachusetts Amherst Libraries4—were the primary organizing entities for Nanoinformatics 2010.

Description: Nanoinformatics is the science and practice of determining which information is relevant to the nanoscale science ...


Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier Casse, Ravinder Banyal, W. Lu, Y. Huang, Selvapraba Selvarasah, Mehmet Dokmeci, Srinivas Sridhar May 2011

Nanoengineering Of A Negative-Index Binary-Staircase Lens For The Optics Regime, Bernard Didier Casse, Ravinder Banyal, W. Lu, Y. Huang, Selvapraba Selvarasah, Mehmet Dokmeci, Srinivas Sridhar

Srinivas Sridhar

We show that a binary-staircase optical element can be engineered to exhibit an effective negative index of refraction, thereby expanding the range of optical properties theoretically available for future optoelectronic devices. The mechanism for achieving a negative-index lens is based on exploiting the periodicity of the surface corrugation. By designing and nanofabricating a planoconcave binary-staircase lens in the InP/InGaAsP platform, we have experimentally demonstrated at 1.55 μm that such negative-index concave lenses can focus plane waves. The beam propagation in the lens was studied experimentally and was in excellent agreement with the three-dimensional finite-difference time-domain numerical simulations.


Nanoinformatics 2010: Community-Wide Collaboration For The Collection, Curation, Analysis, And Dissemination Of Nanotechnology Data, Rebecca C. Reznik-Zellen, Mark Tuominen, Jeff Morse, Robert Stevens Apr 2011

Nanoinformatics 2010: Community-Wide Collaboration For The Collection, Curation, Analysis, And Dissemination Of Nanotechnology Data, Rebecca C. Reznik-Zellen, Mark Tuominen, Jeff Morse, Robert Stevens

University of Massachusetts and New England Area Librarian e-Science Symposium

Objective: To describe the emerging disciplinary community of Nanoinformatics, of which the University of Massachusetts Amherst is a part, and Nanoinformatics 2010, a collaborative roadmapping workshop organized by this community to coordinate the existing but diverse efforts to collect, curate, analyze, and disseminate nanotechnology data.

Participants: InterNano1 and the National Nanomanufacturing Network2—funded by the National Science Foundation Center for Hierarchical Manufacturing3 and administered by the University of Massachusetts Amherst Libraries4—were the primary organizing entities for Nanoinformatics 2010.

Description: Nanoinformatics is the science and practice of determining which information is relevant to the nanoscale science ...


Diodes For Optical Rectennas, Sachit Grover Jan 2011

Diodes For Optical Rectennas, Sachit Grover

Electrical Engineering Graduate Theses & Dissertations

Two types of ultra-fast diode are fabricated, characterized, and simulated for use in optical rectennas. A rectenna consists of an antenna connected to a diode in which the electromagnetic radiation received by the antenna is rectified in the diode. I have investigated metal/insulator/metal (MIM) tunnel diodes and a new, geometric diode for use in rectenna-based infrared detectors and solar cells. Factors influencing the performance of a rectenna are analyzed. These include DC and optical-frequency diode-characteristics, circuit parameters, signal amplitude, and coherence of incoming radiation.

To understand and increase the rectification response of MIM-based rectennas, I carry out an ...


Nanotechnology Education—First Step In Implementing A Spiral Curriculum, Ganesh Balasubramanian, Vinod K. Lohani, Ishwar K. Puri, Scott W. Case, Roop L. Mahajan Jan 2011

Nanotechnology Education—First Step In Implementing A Spiral Curriculum, Ganesh Balasubramanian, Vinod K. Lohani, Ishwar K. Puri, Scott W. Case, Roop L. Mahajan

Ganesh Balasubramanian

A nanotechnology learning module was implemented into a freshman engineering course at Virginia Tech. The novelty of our approach is that an established spiral curriculum model has been employed, for the first time to the best of authors’ knowledge, to design the nanotechnology option. The module was piloted in a freshman class (180 students) during spring ‘08. The key components included (1) a prior knowledge survey, (2) a 40-minute in-class presentation on basic nanotechnology concepts, (3) an activity that involves nanoscale image analysis and the plotting of molecular forces usingLabVIEWsoftware,and(4)apost-modulesurvey.Lessonslearnedfromthepilotimplementationwereincorporated appropriately to expose roughly 1450 freshmen ...


Artificial And Natural Nucleic Acid Self Assembling Systems, Marcus Wood Jan 2011

Artificial And Natural Nucleic Acid Self Assembling Systems, Marcus Wood

Wayne State University Dissertations

Nucleic acids are good candidates for nanomachine construction. They participate in all the processes of life, and so can function as structural building blocks and dynamic catalysts. However, to use nucleic acids as nanomachines, a better understanding of their material properties, how to design structures using them, and their dynamics is needed. We have tried to address these issues, in a small way, with nucleic acid force field development, an attempt at nanostructural design and synthesis using DNA, and a study of the RNA/protein regulatory dynamics of the tryptophan regulatory attenuation protein.


The Use Of Environmental, Health And Safety Research In Nanotechnology Research, Jan Youtie, Alan Porter, Philip Shapira, Li Tang, Troy Benn Dec 2010

The Use Of Environmental, Health And Safety Research In Nanotechnology Research, Jan Youtie, Alan Porter, Philip Shapira, Li Tang, Troy Benn

Li Tang

Environmental, health, and safety (EHS) concerns are receiving considerable attention in nanoscience and nanotechnology (nano) research and development (R&D). Policymakers and others have urged that research on nano's EHS implications be developed alongside scientific research in the nano domain rather than subsequent to applications. This concurrent perspective suggests the importance of early understanding and measurement of the diffusion of nano EHS research. The paper examines the diffusion of nano EHS publications, defined through a set of search terms, into the broader nano domain using a global nanotechnology R&D database developed at Georgia Tech. The results indicate that ...


Effects Of Carbon Nanotube-Tethered Nanosphere Density On Amperometric Biosensing: Simulation And Experiment, Jonathan C. Claussen, James B. Hengenius, Monique M. Wickner, Timothy S. Fisher, David M. Umulis, D. Marshall Porterfield Dec 2010

Effects Of Carbon Nanotube-Tethered Nanosphere Density On Amperometric Biosensing: Simulation And Experiment, Jonathan C. Claussen, James B. Hengenius, Monique M. Wickner, Timothy S. Fisher, David M. Umulis, D. Marshall Porterfield

Jonathan C. Claussen

Nascent nanofabrication approaches are being applied to reduce electrode feature dimensions from the microscale to the nanoscale, creating biosensors that are capable of working more efficiently at the biomolecular level. The development of nanoscale biosensors has been driven largely by experimental empiricism to date. Consequently, the precise positioning of nanoscale electrode elements is typically neglected, and its impact on biosensor performance is subsequently overlooked. Herein, we present a bottom-up nanoelectrode array fabrication approach that utilizes low-density and horizontally oriented single-walled carbon nanotubes (SWCNTs) as a template for the growth and precise positioning of Pt nanospheres. We further develop a computational ...


Small-Scale Solutions To Grand Challenges In Thermal Management, Suresh V. Garimella Nov 2010

Small-Scale Solutions To Grand Challenges In Thermal Management, Suresh V. Garimella

Birck and NCN Publications

Research needs in the field of thermal management of microelectronics and microsystems are identified, followed by a brief discussion of recent advances in solution approaches. These include novel solutions that rely on two-phase flow at the microscale, micropumps, droplet actuation on structured surfaces, passive transport in wick structures, ion-driven and piezoelectrically driven airflow, nanostructured thermal materials, and novel diagnostic tools.


Determining The Electronic Properties Of Individual Nanointerfaces By Combining Intermittent Afm Imaging And Contact Spectroscopy, Ramsey A. Kraya, Dawn A. Bonnell Nov 2010

Determining The Electronic Properties Of Individual Nanointerfaces By Combining Intermittent Afm Imaging And Contact Spectroscopy, Ramsey A. Kraya, Dawn A. Bonnell

Departmental Papers (MSE)

A method to determine the electronic properties at nanointerfaces or of nanostructures by utilizing intermittent contact atomic force microscopy and contact spectroscopy in one system is developed. By combining these two methods, the integrity of the interface or structure is maintained during imaging, while the extraction of the electronic information is obtained with contact spectroscopy. This method is especially vital for understanding interfaces between metal nanoparticles and substrates, where the nanoparticles are not tethered to the surface and can be combined with new and evolving techniques of thermal drift compensation to allow for a larger range of experiments on nanointerfaces ...


Artificial Intelligence: Soon To Be The World’S Greatest Intelligence, Or Just A Wild Dream?, Edward R. Kollett Mar 2010

Artificial Intelligence: Soon To Be The World’S Greatest Intelligence, Or Just A Wild Dream?, Edward R. Kollett

Academic Symposium of Undergraduate Scholarship

The purpose of the paper was to examine the field of artificial intelligence. In particular, the paper focused on what has been accomplished towards the goal of making a machine that can think like a human, and the hardships that researchers in the field has faced. It also touched upon the potential outcomes of success. Why is this paper important? As computers become more powerful, the common conception is that they are becoming more intelligent. As computers become more integrated with society and more connected with each other, people again believe they are becoming smarter. Therefore, it is important that ...


An Alternative Method To Determining Optical Lever Sensitivity In Atomic Force Microscopy Without Tip-Sample Contact, Christopher J. Tourek, Sriram Sundararajan Jan 2010

An Alternative Method To Determining Optical Lever Sensitivity In Atomic Force Microscopy Without Tip-Sample Contact, Christopher J. Tourek, Sriram Sundararajan

Mechanical Engineering Publications

Force studies using atomic force microscopy generally require knowledge of the cantilever spring constants and the optical lever sensitivity. The traditional method of evaluating the optical lever sensitivity by pressing the tip against a hard surface can damage the tip, especially sharp ones. Here a method is shown to calculate the sensitivity without having to bring the tip into contact. Instead a sharpened tungsten wire is used to cause a point contact directly onto the cantilever and cause cantilever bending. Using beam theory, the sensitivity thus found can be converted to the equivalent sensitivity that would be obtained using the ...


Vertical Carbon Nanotube Devices With Nanoscale Lengths Controlled Without Lithography, Aaron D. Franklin, Robert A. Sayer, Timothy D. Sands, David B. Janes, Timothy S. Fisher Jul 2009

Vertical Carbon Nanotube Devices With Nanoscale Lengths Controlled Without Lithography, Aaron D. Franklin, Robert A. Sayer, Timothy D. Sands, David B. Janes, Timothy S. Fisher

PRISM: NNSA Center for Prediction of Reliability, Integrity and Survivability of Microsystems

Vertical single-walled carbon nanotubes (vSWCNTs) are synthesized within highly ordered porous anodic alumina (PAA) templates supported on Si substrates. A process for obtaining thin-film PAA with long-range ordered nanopores is presented in this paper. Each nanopore contains at most one v-SWCNT that is supported by a dielectric and addressed by electrochemically formed Pd nanowire source contacts and evaporated Pd drain contacts. Characteristics of these completely vertical, two-terminal nanotube devices are presented. Control of the v-SWCNT length is demonstrated using a straightforward etching process with lengths of less than 100 nm achieved without the need for complex/expensive lithography. This effective ...


Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck Mar 2008

Structural Identification Of Cubic Iron-Oxide Nanocrystal Mixtures: X-Ray Powder Diffraction Versus Quasi-Kinematic Transmission Electron Microscopy, Peter Moeck

Physics Faculty Publications and Presentations

Two novel (and proprietary) strategies for the structural identification of a nanocrystal from either a single high-resolution (HR) transmission electron microscopy (TEM) image or a single precession electron diffraction pattern are proposed and their advantages discussed in comparison to structural fingerprinting from powder X-ray diffraction patterns. Simulations for cubic magnetite and maghemite nanocrystals are used as examples.


Physiochemical Indicators Of Single Walled Carbon Nanotube Toxicity, Alan Casey Jan 2007

Physiochemical Indicators Of Single Walled Carbon Nanotube Toxicity, Alan Casey

Doctoral

Numerous toxicity studies have been conducted to date both in vivo and in vitro on refined and raw Single Walled Carbon Nanotubes (SWCNT). Differences in SWCNT toxicity and biocompatibility have been observed between these studies, and whilst these discrepancies have been attributed to factors such as varying percentages of remnant catalytic particles, differences in dispersion methods etc. the mechanisms underlying these inconsistencies have not been investigated. This study used standard spectroscopic and cellular techniques to elucidate the origins of these inconsistencies and also to estimate the validity of toxicological data evaluated form standard cytotoxic endpoints. Spectroscopic studies were conducted in ...


Transmission Electron Goniometry And Its Relation To Electron Tomography For Materials Science Apoplications, Peter Moeck, P. Fraundorf Nov 2006

Transmission Electron Goniometry And Its Relation To Electron Tomography For Materials Science Apoplications, Peter Moeck, P. Fraundorf

Physics Faculty Publications and Presentations

Aspects of transmission electron goniometry are discussed. Combined with high resolution phase contrast transmission electron microscopy (HRTEM) and atomic resolution scanning TEM (STEM) in the atomic number contrast (Z-STEM) or the phase contrast bright field mode, transmission electron goniometry offers the opportunity to develop dedicated methods for the crystallographic characterization of nanocrystals in three dimensions. The relationship between transmission electron goniometry and electron tomography for materials science applications is briefly discussed. Internet based java applets that facilitate the application of transmission electron goniometry for cubic crystals with calibrated tilt-rotation and double-tilt specimen holders/goniometers are mentioned. The so called cubic-minimalistic ...


Progress Towards Terahertz Acoustic Phonon Generation In Doping Superlattices, Thomas E. Wilson Oct 2005

Progress Towards Terahertz Acoustic Phonon Generation In Doping Superlattices, Thomas E. Wilson

Physics Faculty Research

Progress is described in experiments to generate coherent terahertz acoustic phonons in silicon doping superlattices by the resonant absorption of nanosecond-pulsed far-infrared laser radiation. Future experiments are proposed that would use the superlattice as a transducer in a terahertz cryogenic acoustic reflection microscope with sub-nanometer resolution.


Making Sense Of Nanocrystal Lattice Fringes, P. Fraundorf, Wentao Qin, Peter Moeck, Eric Mandell Jan 2005

Making Sense Of Nanocrystal Lattice Fringes, P. Fraundorf, Wentao Qin, Peter Moeck, Eric Mandell

Physics Faculty Publications and Presentations

The orientation dependence of thin-crystal lattice fringes can be gracefully quantified using fringe-visibility maps, a direct-space analog of Kikuchi maps [Nishikawa and Kikuchi, Nature (London) 121, 1019 (1928)]. As in navigation of reciprocal space with the aid of Kikuchi lines, fringe-visibility maps facilitate acquisition of crystallographic information from lattice images. In particular, these maps can help researchers to determine the three-dimensional lattice of individual nanocrystals, to 'fringe-fingerprint' collections of randomly oriented particles, and to measure local specimen thickness with only a modest tilt. Since the number of fringes in an image increases with maximum spatial-frequency squared, these strategies (with help ...


Nanofatigue Studies Of Ultrathin Hard Carbon Overcoats Used In Magnetic Storage Devices, Xiaodong Li, Bharat Bhushan May 2002

Nanofatigue Studies Of Ultrathin Hard Carbon Overcoats Used In Magnetic Storage Devices, Xiaodong Li, Bharat Bhushan

Faculty Publications

A technique to perform nanofatigue experiments was developed. This technique utilizes a depth-sensing nanoindenter with harmonic force. The nanofatigue behavior of 20 nm thick amorphous carbon coatings was studied. The contact stiffness was monitored continuously throughout the test. The abrupt decrease in the contact stiffness indicates fatigue damage has occurred. The critical load amplitude, below which no fatigue damage occurs, was identified. It was found that the filtered cathodic arc coating exhibits longer fatigue life than a direct ion beam coating. Failure mechanisms of the coatings during fatigue are also discussed in conjunction with the hardness,elastic modulus, and fracture ...