California NanoSystems Institute
CNSI
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December 06, 2005

David Goldhaber-Gordon
Stanford University


Streaming Video
  

Spintronics and Probing the Nanoscale
Electrons behave in remarkable ways when confined to fewer than three dimensions. Take for example a quantum point contact: a narrow constriction between two electron reservoirs, often thought of as a short 1-dimensional wire. The width of the constriction can be tuned so as to pass zero, one, two, or more channels of electrons, each with a quantized conductance of 2e^2/h (around 80 uSiemens). As a point contact is just being opened up, its conductance pauses around 0.7 times 2e^2/h, before rising to the first full-channel plateau. This "0.7 plateau" has been a prominent puzzle since 1994. I will discuss some recent experiments on quantum point contacts which shed light on the spin-related origin of this phenomenon.

In the later part of my talk, I will introduce some of the research on mapping electronic, magnetic, and optical properties of nanostructures being done in the new Stanford-IBM Center for Probing the Nanoscale, an NSF Nanoscale Science and Engineering Center of which I am Deputy Director.

November 29, 2005

Eli Yablonovitch
UCLA


Streaming Video
  

The Impedence-Matching Predicament: A Hurdle in the Race Toward Nano-Electronics
In contemplating the headlong rush toward miniaturization represented by Moore's Law, it is tempting to think only of the progression toward molecular sized components.

There is a second aspect of Moore's Law, that is sometimes overlooked. Because of miniaturization, the energy efficiency of information processing steadily improves. We anticipate that the energy required to process a single bit of information will eventually become as tiny as 1 electron-Volt per function, truly indeed a molecular sized energy. Inevitably most logic functions including storage, readout, and other logical manipulations will eventually be that efficient. However there is one information-processing-function that bucks this trend. That is communication, especially over short distances. Our best projections of improvements in the short distance communication function show that it will still require hundreds of thousand of electron-Volts, just to move a bit of information the tiny distance of only 10 micro-meters.

Why this energy per bit discrepancy for communications? It is caused by the difference in length scale between the wires and the molecular size devices. Wires are long and that leads to a low impedance, devices are tiny and they have a high impedance. The challenge then is to find, discover, or invent a nano-scale impedance transformer, that can bring the energy efficiency of communications in line with the excellent efficiency of all the other bit functions.

November 15, 2005

Paul Selvin
University of Illinois


Streaming Video
  

Nanobiology: Studying Single-Molecule Molecular Motors
Abstract:

We have achieved 1.5 nm resolution using fluorescence imaging, approximately 300 times better than the diffraction limit of conventional light. Recently we have been able to increase the time resolution to 1 msec, from a previous value of 500 msec. Using this increased time-resolution, we have looked at molecular motors inside living cells. We have been able to see individual cargos being moved by individual kinesin and dynein, two important motors. We find that both kinesin and dynein move cargo 8 nm per ATP (the universal food of the cell), in opposite directions in a cell. Amazingly, these two molecular motors do not engage in a tug-of-war, but appear to be cooperative, giving the particle extra speed.

References:

1. Myosin V Walks Hand-Over-Hand: Single Fluorophore Imaging with 1.5-nm Localization (PDF)
Ahmet Yildiz, Joseph N. Forkey, Sean A. McKinney, Taekjip Ha, Yale E. Goldman, Paul R. Selvin

November 08, 2005

Gordon Wallace
University of Wollongong, Australia


Streaming Video
  

Nanosctructured Organic Conductors - Implications for New Biocommunication Platforms
Abstract:

Organic electrofunctional materials such as inherently conducting polymers (ICPs) and carbon nanotubes (CNTs) provide a conduit to the biological world hitherto unavailable. They posses unique electronic and electrochemical properties and these properties, combined with the diverse chemistries and biochemistries that can be integrated into their structure, provide a powerful new biocommunications platform.

In our laboratories we have been particularly interested in the use of ICPs (e.g. polypyrrole), to provide control mechanisms over biomolecular interactions such as antibody-antigen or substrate-enzyme processes. The control of more complex processes occurring in living cells has also been of interest. We and others have shown that nerve cells can be cultured on ICP surfaces and that small electrical stimuli can be used to stimulate neurite outgrowth. Biocommunications at the whole body level (wearable sensors and artificial muscles) have also been explored.

In parallel programs we have shown that the creation of nanostrutcures based on ICPs provides a greater degree of control over electronic, mechanical and molecular interactions and hence provides a basis for more effective biocommunication systems. ICP nanostructures can be fabricated using a number of approaches1 that utilize either molecular or physical templates. Alternatively nanostructured CNT fibres with biomolecules attached can be achieved by wetspinning. It is envisaged that this control at the nanodimension will enable more effective biocommunications from the molecular to the whole body level.2,3,4

References:

1. "Inherently Conducting Polymer Nanostructures" Innis, P.C., Wallace, G.G. Journal of Nanoscience and Nanotechnology 2002, 2 (5), 441-451.

2. "Bionic Ears: Their Development and Future Advances Using Neurotrophins and Inherently Conducting Polymers" Clark, G.M., Wallace, G.G. Journal of Applied Bionics and Biomechanics In Press.

3. "An Amperometric Enzyme Biosensor Fabricated from Polyaniline Nanoparticles" Morrin, A., Ngamna, O., Killard, A.J., Moulton, S.E., Smyth, M.R., Wallace, G.G. Electroanalysis 2005, 17 (5-6), 423-430.

4. "Biosensors Based on Aligned Carbon Nanotubes Coated with Inherently Conducting Polymers" Gao, M., Dai, L., Wallace, G.G. Electroanalysis 2003, 15 (13), 1089-1094.

November 01, 2005

George Bourianoff
Intel/FENA
The Search for Alternative Logic Devices Beyond CMOS in the 2020 Timeframe
Abstract:

Intel believes nanotech materials and structures hold great promise for both the ultimate scaling of CMOS devices as well as the discovery of new information processing beyond CMOS. We feel that the FET device and the CMOS implementation is a very robust and sophisticated structure that operates at close to theoretical optimum for charge based devices and that it can be scaled for at least another 15 years. Beyond that, CMOS technology will become the integration platform for alternative logic technologies that will begin to emerge in the 2020 time frame. These technologies are currently being investigated in many research institutions around the world.

This presentation will survey the prospects for the emerging alternative logic technologies, based on the work of the Emerging Research Device group of the ITRS as well as other industrial working groups. It will analyze six alternative logic technologies currently being investigated including spin devices, molecular devices and ferromagnetic devices. Looking forward, a consensus is emerging around five important research vectors can potentially produce the next logic device. The five research vectors will be discussed and examples given.

Biography:

George Bourianoff is the manager of Emerging Research Technologies in the External Programs Group at Intel. He is responsible for communicating Intel stakeholder research objectives to the external research community and managing Intel's external semiconductor research program in universities and other research organizations. Dr. Bourianoff serves as co-chair of the Semiconductor Technology Committee as well as the optoelectronic and nanotechnology SRSs. Currently he has research interests in spintronics, optoelectronics, strongly coupled electron systems and devices.

Dr Bourianoff holds a BS, MS and PhD in Physics from the University of Texas at Austin. He has over 80 publications spanning computational physics, hydrodynamics, plasma physics, beam physics, accelerator physics and semiconductor device physics. Prior to joining Intel, Dr. Bourianoff was a group leader at the Superconducting Supercollider Laboratory in Texas.

October 25, 2005

Ric Kaner
UCLA


Streaming Video
  

Synthesis and Applications of Polyaniline Nanofibers
Abstract:

Conducting polymer nanostructures have attracted a great deal of research interest with the expectation that the combination of organic conducting materials and nanostructures could yield new functional materials or enable new physiochemical properties. By modifying conventional chemical oxidation polymerization processes, we have developed simple approaches to synthesize polyaniline nanofibers with diameters tunable from 30 to 120 nm (Figure 1A) including interfacial polymerization and a rapid mixing process.[1,2,3]

Compared to conventional polyaniline, polyaniline nanofibers exhibit higher surface area and significantly improved water dispersibility, which can dramatically enhance many applications such as in chemical sensors. The sensitivity of nanofiber-based sensors can be improved by several orders of magnitude while the response time is significantly shortened (Figure 1B).[4,5] Unlike conventional polyaniline films, nanofiber films show no thickness dependence to their response to vapors.

We have recently discovered that polyaniline nanofibers exhibit an exceptional photothermal effect.[6] The nanofibers can be instantaneously melted and cross-linked upon exposure to a camera flash. By taking advantage of this effect, a novel flash welding technique has been developed that can be used to make asymmetric polymer membranes, form patterned nanofiber films, create polymer based nanocomposites and mechanical actuators (artificial muscles). Polyaniline nanofibers can even be decorated with metal nanoparticles and used in molecular memory devices.

References:

[1] Huang, J.; Virji, S.; Weiller, B. H.; Kaner, R. B. J. Am. Chem. Soc. 2003, 125, 314.

[2] Huang, J.; Kaner, R. B. J. Am. Chem. Soc. 2004, 126, 851.

[3] Huang, J.; Kaner R. B. Angew. Chem. Inter. Edition 2004, 43, 5817.

[4] Virji, S.; Huang, J; Kaner R. B.; Weiller B. H. Nano Lett. 2004, 4, 491.

[5] Huang, J.; Virji, S.; Weiller, B. H.; Kaner, R. B. Chem.-Eur. J. 2004. 10, 1314.

[6] Huang, J.; Kaner, R. B. Nature Mater. 2004, 3, 783.

[7] Tseng, R.; Huang, J; Ouyang, J., Kaner R. B.; Yang, Y. Nano Lett. 2005, 5, 1077.

October 18, 2005

Carolyn Bertozzi
UC Berkeley
CANCELLED

October 11, 2005

Nicola Pohl
Iowa State University


Streaming Video
  

Fluorous-Based Microarray Patterning and Thermostable Biocatalyst Discovery: Implications for Nanotechnology
Abstract:

Biological systems, dominated by noncovalent interactions, serve as both inspiration and building blocks for the rational design of new nano-scaled systems. This talk will highlight how a quest for glycomics tools led to new methods for surface patterning and finding more robust protein building blocks. Specifically, probing genomic information with a chemist's eye has led to the discovery of particularly promiscuous and thermostable enzymes. To generate small molecule microarrays for screening of enzymes and other proteins, a new method for surface patterning using noncovalent fluorous interactions has been developed. The application of this array technology to carbohydrates and its implications in simplifying and potentially automating chemical and enzymatic oligosaccharide synthesis will be presented along with what we still need to learn to apply such fluorous-based approaches in fabricating other arrays and devices.

References:

1. Fluorous-Based Carbohydrate Microarrays (PDF) Kwang-Seuk Ko, Firoz A. Jaipuri, and Nicola L. Pohl
October 04, 2005

Neil Branda
Simon Fraser University


Streaming Video
  

Molecular Switching of Structure and Function for Nanotechnology Applications
Abstract:

Molecular switching is an interdisciplinary area of research lying at the crossroads of chemistry and materials science and is key to the successful miniaturization and controlled operation of the components of nano-scale machinery. Photochromic compounds can be interconverted between two isomeric forms when they are exposed to specific wavelengths of light. Because each form exhibits unique characteristics such as colour, fluorescence, refractive index and redox properties, photochromic systems are important to the advancement of controllable electronic devices such as optical recording media, display materials and molecular electronics, and to health science applications such as drug delivery and sensing. This talk will highlight representative examples of photochromic systems and will emphasize how the scope of potential applications for photochromic materials can harness other structural and electronic changes that accompany the photochromic event include variations in topology and skeletal flexibility as well as variations in acidity and reactivity. Representative examples will include systems that help to regulate the role of synthetic reagents and catalysts, those that can be integrated into sensors and drug delivery systems and those that modulate the properties of membranes.

Biography:

As a 2005 NSERC Steacie Fellowship winner and a Canada Research Chair in Materials Science, Neil Branda has been recognized as one of Canada's leading young scientists. Dr. Branda is currently a Professor of Chemistry at Simon Fraser University and Director of Molecular Systems at 4D LABS, Simon Fraser University's new $35 million research facility for new materials and nanoscale devices. His research program lies at the interface of organic chemistry and materials science with a focus on designing and synthesizing molecular switches - molecules that change their structure and function when triggered with light, electricity or chemical stimuli. Dr. Branda works closely with materials scientists and the medical research community to deliver unprecedented designer photoswitches to solve practical challenges in molecular photonics, electronics, therapeutics and diagnostics. His research program involves integrating photo- and electro-responsive molecules into digital data storage systems, synthetic reagents and catalysts, sensors and dosimeters and drug delivery systems, using light as a trigger to selectively unmask known drug architectures as well as using optics to control important metabolic intermediates and enzyme cofactors.

Dr. Branda received his B.Sc. from the University of Toronto and his Ph.D. from Massachusetts Institute of Technology. He was a Natural Sciences and Engineering Research Council of Canada Postdoctoral Fellow at l'University © Louis Pasteur, then joined the faculty at the University of Alberta before moving to Simon Fraser University.