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Gaithersburg, MD, United States

Ferrance J.P.,J 2 F Engineering | Ferrance J.P.,University of Virginia | Ferrance J.P.,Pettit Applied Technologies Inc.
Electroanalysis | Year: 2011

Strings of single-walled carbon nanotubes (SWCNT) were prepared using an aqueous dispersion of gellan gum wrapped nanotubes and crosslinked using Ca 2+ ions. Various formulations were evaluated to determine the parameters for successful string formation; these included 8-12% nanotube by weight, 60-70% gellan gum, and 20-30% KCl. Strings showed electrical conductivity when dried between ITO electrodes. Conductivity variations were observed and potential sources of the variation identified. Proteins were attached to the carbon nanotube strings with peroxidase enzymatic activity detected following horseradish peroxidase attachment. This work provides a basis for development of electronic biosensors based on these carbon nanotube strings. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 950.00K | Year: 2004

This project is to build and test several passive optical sensors needed for AFRL Fly-by-Light systems based on carbon nanotube technology that has been developed in the Phase I efforts. The sensors will be developed to meet the important AFRL Fly-by-Light requirements of insensitivity to light amplitude, high degree of EMI/RFI immunity, exceptional small size, measurement sensitivity, response time and compatibility with WDM multimode and single mode fiber optic networks. A sensor test facility including VCSEL light source, fiber optic network and a receiver module will be designed and fabricated. Sensors to measure magnetic field, voltage, current and temperature will be built and tested. Performance tests of these sensors with respect to the key requirements will be conducted in a high EMI/RFI field environment.

Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 99.78K | Year: 2003

Completely optical sensors that work entirely without the use of electricity are very desirable devices for many important industrial, military and national security uses. Numerous so-called

Ferrance J.P.,Pettit Applied Technologies Inc. | Ferrance J.P.,University of Virginia | Meissner K.E.,Texas A&M University | Pettit J.W.,Pettit Applied Technologies Inc.
Journal of Nanoparticle Research | Year: 2010

Optical signals were used to modulate the resistance of single-walled carbon nanotube-polymer composite films for development of optical switching devices. Films were fabricated from nanotubes dispersed in poly(2-methoxy-5-(2'- ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) solutions in either tetrahydrofuran (THF) or toluene. MEH-PPV was affected by the solvent choice, with THF causing an absorbance shift to shorter wavelengths. Composite films formed from THF dispersions showed 1-4% resistance decreases when illuminated with a green diode laser. Illumination of toluene-based films showed up to 5.4% resistance decreases, smaller than expected based on the polymer solution absorbance. Fluorescent emission from the polymer in toluene appears to inhibit charge transfer from the polymer to the nanotubes. THF films were unaffected by illumination with a red diode laser, while toluene dispersion films showed resistance decreases up to 1%. Nanotube dispersion and film formation reproducibility, evaluated for both the solvents, showed that the solvent affected film resistance and dispersion stability. © Springer Science+Business Media B.V. 2009. Source

Ferrance J.P.,Pettit Applied Technologies Inc. | Ferrance J.P.,University of Virginia | Juriani A.R.,Texas A&M University | Pettit J.W.,Pettit Applied Technologies Inc. | Meissner K.E.,Texas A&M University
Journal of Nanoelectronics and Optoelectronics | Year: 2011

The photoresponse of single walled carbon nanotube films was studied in the presence of CdSe nanocrystals. Films were fabricated from aqueous dispersions of both nanotubes and nanocrystals, allowing the effects of the dispersants on the photoresponse to be determined. Gellan gum and single stranded DNA were used to disperse the carbon nanotubes, with the DNA providing a dispersion of nanotubes with higher negative surface charge. CdSe nanocrystals were dispersed in aqueous solution using both dihydrolipoic acid and polyethyleneimine to produce nanocrystals with negative and positive surface charges, respectively. Dispersions of dihydrolipoic acid capped nanocrystals incorporated into nanotube films provided time dependent increases in the film resistance upon laser illumination that could exceed a 50% increase from the baseline resistance. This response resulted from a combination of electron transfer from excited nanocrystals and charge gating of the nanotube Fermi level by the positively charged nanocrystals. Photo-responsive nanotube films fabricated using CdSe nanocrystals dispersed with polyethyleneimine also displayed time dependent resistance increases upon illumination that could exceed 100% of the baseline resistance. Decreasing the number of PEI coated nanocrystals resulted in a smaller response as expected. Time constants for these responses were 34.5 s for the DHLA capped nanocrystals and 18.5 s for the PEI coated nanocrystals, with the difference most likely due to electrostatic interaction effects with the negative charges on the nanotube surface. Copyright © 2011 American Scientific Publishers All rights reserved. Source

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