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No description available.

The Nanoinjector Lance Array has been developed to inject foreign material into thousands of cells at once using electrophoresis to attract and repel particles to and from the electrically-charged lances. A mathematical computer model simulating the motion of attracted or repelled proteins informs the design of the nanoinjection lance array system. The model is validated by accurately predicting protein velocity in electrophoresis experiments. A complete analysis of parameters is conducted via simulations and specific research questions regarding the counter electrode of the nanoinjector lance array system are explored using the model. A novel technique for fabricating lance arrays from collapsed carbon nanotube forests is explored and detailed. Experiments are conducted using the Nanoinjector Lance Array, attempting to inject three different kinds of protein molecules into a culture of HeLa cells. The experimental results are encouraging and suggest possibilities for future success. Other recommendations are made for future research regarding the model, carbon nanotube fabrication, and experimental testing.

A method is described for ultrasonically spraying thin films of carbon nanotubes that have been suspended in organic solvents. Nanotubes were sonicated in N-Methyl-2-pyrrolidone or N-Cyclohexyl-2-pyrrolidone and then sprayed onto a heated substrate using an ultrasonic spray nozzle. The solvent quickly evaporated, leaving a thin film of randomly oriented nanotubes. Film thickness was controlled by the spray time and ranged between 200-500 nm, with RMS roughness of about 40 nm. Also described is a method for creating thin (300 nm) conductive freestanding nanotube/polymer composite films by infiltrating sprayed nanotube films with polyimide.

As individual health monitors continue to become more widely adopted in helping individuals make informed decisions, new technologies need to be developed to obtain more biometric data. Spectroscopy is a well-known tool to gain biological information. Traditionally spectrometers are large and expensive making personal or wearable health monitors difficult. Here we present the development and characterization of a miniaturized short wavelength infrared spectrometer for wearable applications. We present a carbon nanotube parallel hole collimator can effectively select a narrow set of allowed angles of light to be separated by a linear variable filter and detected at a photodiode array making a spectrometer. We will go over the calibration of the spectrometer showing a resolution of 13 nm at 1300 nm. Improvements on the original collimator data will be discussed, including carbon nanotube growth without infiltration and growth on transparent substrates. We will also show measurements made on human subjects yielding a pulse.

Composite materials are extensively used as an advanced engineering material, particularly in aerospace, automotive, and buildings industries due to its superior properties such as high strength to weight ratios and resistance to corrosion. As composite materials are rapidly replacing traditional materials in aircraft manufacturing, improved methods of identifying damage and critical failure is in development. One of the most commonly used procedures utilizes a health monitoring system that relies on transducers to monitor transmitted waves generated by ultrasonics. By replacing this method with a nanotechnology-based one, it is possible to efficiently detect damage without the time-extensive process of scanning the structure. This research investigated the development of a nanomaterial-based sensor for health monitoring of composite structures. To develop the sensor, carbon nanotube/epoxy mixture (2%wt CNT) was coated on a strand of E-glass fibre to be adhered onto a fiberglass composite specimen. The selection of E-glass fibre and fibreglass plate was largely due to its electrical insulating properties to demonstrate that the carbon nanotube is driving the sensing capabilities through its highly conductive nature. In addition, by adhering the coated E-glass fiber to a fibreglass coupon, the homogeneity and material properties were approximately maintained. Tensile testing of the specimen conducted through a Lloyd LD50 tensile testing machine provided data on the actual strain which was correlated with the experimental differential resistances measured by a multimeter, both at the same specified tensile loading conditions. With two sets of data, the experimental resistance data was calibrated with the actual strain data collected. Ultimately, the experimental sensors created a sample of gauge factors which represents 91.24% probability of replicating the observed range of gauge factors by using the same manufacturing procedures, providing a valid alternative and consistent method to detecting composite damage.

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Carbon nanotube templated microfabrication (CNT-M) is a method that allows high-aspect ratio structures to be made for microelectromechanical systems (MEMS) devices. One concern when making monolithic electrical devices using CNT-M is that the aluminum oxide diffusion barrier will create too large of a resistance in the device. However, in developing CNT based MEMS devices, it has been observed that an electrical DC current is capable of transport from a conductive substrate, across the aluminum oxide, and through to the CNT structure grown on top of it. This thesis attempts to determine the mechanisms responsible for current being able to cross the aluminum oxide diffusion barrier easily through sample characterizations. Principally, current-voltage measurements, electron microscopy, XEDS, and SIMS analysis are used to characterize the various samples and determine the process responsible for the observed phenomenon. Through these techniques, it is determined exposure to ethylene gas during the CNT growth recipe used in our lab, regardless of whether CNTs grow on the sample or not, is necessary to cause a drop in resistance across the aluminum oxide, but the that the overall content of iron and carbon in the aluminum oxide do not correlate with this drop in resistance.

In this research, different anionic dopants were investigated for the fabrication of polypyrrole (PPy) electrode materials for electrochemical capacitors (ECs). Anionic dopants from catechol, salicylic acid and chromotropic acid family allowed for the formation of adherent PPy thin film on stainless steels current collectors by electropolymerization. Comparison between galvanostatic and pulse electropolymerization of PPy thin films was made. Pulse electropolymerization was found to provide improved impregnation of Ni plaque current collectors and formation of nanostructured coating. The electrodes prepared by pulse electropolymerization showed higher porosity, lower electrical resistance, higher capacitance and improved cyclic stability. In order to overcome the mass loading limitation for thin film PPy electrodes, chemical polymerization of PPy was investigated. The use of fine particles, prepared by the chemical polymerization method, allows impregnation of Ni foams and fabrication of porous electrodes with high materials loading. Moreover, improved capacitive performance and cyclic stability was obtained for PPy electrodes with high materials loading using new anionic dopants. To further improve the cyclic stability of PPy electrodes, multiwalled carbon nanotubes (MWCNT) were used for the fabrication of PPy-MWCNT composite materials due to their high surface area and excellent conductivity. Different dispersants as well as dispersing methods were studied in order to obtain stable MWCNT suspensions. Among those dispersants, multifunctional anionic dopants were found to benefit the formation of MWCNT suspension as well as the polymerization of PPy. A conceptually new approach has been developed for the fabrication of PPy coated MWCNT based on the use of multifunctional anionic dopants. The use of PPy coated MWCNT allowed excellent electrochemical performance for high active mass loadings, required for commercial EC applications. The electrodes and devices made of PPy coated MWCNT showed high capacitance, good capacitance retention at high charge-discharge rates and good cycling stability. The record high capacitance achieved at high charge-discharge rates is promising for the development of high power ECs. / Thesis / Doctor of Philosophy (PhD)

Carbon nanotubes are known as ideal fillers for polymer systems; the main advantage of carbon nanotubes over other nano-reinforcing particles is the combination of superior strength and stiffness with large aspect ratio. Carbon nanotubes may improve the mechanical, electrical and thermal properties of polymers, but to realise their potential in polymer systems uniform dispersion, strong interfacial adhesion and alignment of nanotubes within the polymer matrix are necessary. These properties are not easy to achieve and they are key challenges in producing CNT/Polymer system. This research was carried out in an attempt to understand how the properties of CNT/Polymer composite can be optimised by manipulation of additives, compounding and postcompounding conditions. Polypropylene/Multi-Walled Carbon Nanotube (PP/MCNT) composites were prepared by conventional twin screw extrusion. Dispersants and compatibilisers were used to establish good interaction between filler and polymer. Several different extruder screw configurations were designed and the properties of PP/MCNT composite prepared by each configuration investigated. The results indicated that the addition of carbon nanotubes without additives enhanced mechanical, electrical and thermal properties of polypropylene polymer. Incorporation of compatibilisers into PP/MCNT improved the stiffness but decreased the strength of the nanocomposite, whilst addition of dispersants decreased the mechanical properties of the nanocomposite. Addition of both additives at high concentration improved electrical conductivity and induced electrical percolation in the nanocomposite. Extruder screw configuration was found to have significant effect on the electrical conductivity whilst only slightly affecting mechanical properties of the nanocomposite, possibly due to the competition between dispersion and degradation of polymer chains and possible reduction of carbon nanotube length by intensive shear during compounding. The use of screw configuration with high mixing intensity promoted the dispersion of nanotubes and favoured the conduction process in the nanocomposite. Finally in an attempt to improve dispersion and alignment of carbon nanotubes, compounded PP/MCNT composite was subjected to micromoulding, fibre spinning and biaxial stretching processes and the resultant properties investigated. Application of post-compounding process was found to have significant effect on mechanical and rheological properties of the nanocomposite. Stiffness and strength of the nanocomposites treated by post-compounding processes were found to increase by up to 160% and 300%, respectively. The reinforcement effect of carbon nanotubes in the stretched nanocomposites was found to be the greatest. Rheological analysis suggested that the application of post-compounding processes enhanced dispersion of carbon nanotubes within the nanocomposite. Overall, this finding of this research has shown that carbon nanotubes can be incorporated into polypropylene using conventional equipment to provide significant improvement in properties. By careful choices of additives, compounding and postcompounding conditions, specific properties can be further enhanced. / Ministry of higher education in Kurdistan region in Iraq.