Research areas:
- Carbon Nanotube (CNT) Properties, Devices, and Fabrication
- Nanoelectromechnical (NEMS) Resonators
- Micro- and Nano-fabrication for
Investigations in Cellular and Molecular Biology
Potential applications:
- CNT Transistors
- CNT Films for Solar and Fuel Cells
- CNT Flow Measurement Devices
- CNT-CMOS Integration
- NEMS Gas Sensors
- Nanobiotechnology
- Nanomanufacturing
Brief Description of Research Projects :
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Nanofabrication for Investigations in Cellular and Molecular Biology
Many functional complexes in biology rely in fundamental ways on multiple weak binding interactions with nanometer-scale spatial order. The combined strength of multiple weak interactions can be orders of magnitude larger than that of the individual interactions, forming the basis for the extraordinary specificity of many biochemical systems. Understanding the details of the relationship between spatial order and biochemical function will yield enormous insight into the fundamental workings of these systems. Until now, it has been exceedingly difficult to study this relationship, largely because the size scales involved are those of biomolecules, i.e. from a few to tens of nanometers. Because of continuing progress in solid-state nanofabrication technology, it is now possible to fabricate structures in precisely this size range. It is the objective of the project described below to implement a system that mimics biological spatial order by using nanofabricated structures to provide multiple binding sites at nanometer-scale separations. The nanostructures will be organized into hierarchical arrays in which structural parameters (spacing, etc.) are systematically varied on the micron scale. These arrays will be used to probe the spatial distributions of binding sites in biologically important molecules, to serve as templates for the seeding of protein crystals, and to study the effects of spatial organization on motor proteins.
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Technologies for Nano-Electromechanical Systems and Applications
Nanoelectromchanical systems (NEMS) have offered great promise for applications in mechanical signal processing and ultrasensitive detection. on the application of electrothermal tuning to nanomechanical resonators made from ultra-thin (30nm thick) films, in order to evaluate the effectiveness of this technique for nanoscale structures. NEMS resonators can be used for highly sensitive, specific gas phase detection. It should be possible to extend this technique to other gas phase systems by employing beams with different composition. SiC nanomechanical resonators made from 30 nm-thick 3C-SiC films have a fundamental flexural mode resonance frequency that is tunable over a wide range of frequencies (14% from the base frequency) by electrothermal power on the order of microwatts.
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Controlled Placement of Individual Carbon Nanotubes
A central challenge of nanoscience is to develop tools and processes for the manipulation of objects millions of times smaller than human hands. This challenge is particularly relevant for single-walled carbon nanotubes (SWNTs): because very small variations in structure can produce either semiconducting or metallic behavior, a priori control of nanotube device properties has proven elusive. Here we report a simple, yet powerful, technique for transferring a pre-characterized long single-walled carbon nanotube onto an arbitrary substrate with micron precision. This technique greatly reduces the randomness in bottom-up nanodevice fabrication, and paves the way toward fabrication of devices with fully determined crystal structure and precise location on arbitrary substrates. Such devices will enable more detailed studies of the fundamental physics and chemistry of SWNTs, and provide a stepping stone toward implementation of a wide spectrum of applications promised by this remarkable material.
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Carbon Nanotube Films for Fuel and Solar Cells
Transparent and conducting films are used in modern technologies like video displays, solar cells, lasers, optical communication devices and solid state lighting. Carbon nanotube films are also a class of conducting materials that are gaining a lot of attention due to their extraordinary optical transparency as well as low sheet resistance. These conducting nanotube films are a potential candidate for usage in dye sensitized solar cells as well as fuel cells, where they can be used both as conducting electrode materials as well as catalyst support for enhacing the electrochemical reaction.
- Carbon Nanotube Growth
Ultralong and aligned nanotubes are grown using a rapid-heating CVD technique with carbon monoxide as a feedstock. Nanotubes can be grown on Si substrates for electronic measurements or suspended across holes in Si wafers for optical measurements. We are interested in techniques for controlled device fabrication and applications of nanotubes as sensors and high-performance electronics.
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Suspended Carbon Nanotubes
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Carbon Nanotube Field Effect Transistors
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- Carbon Nanotube Interconnects
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- Carbon Nanotube Flow Sensor
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- Micropillars for Studying Force Transduction in Bacteria
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- Nanopatterned Surfaces for Studying Lipid Bilayers
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