Desde a descoberta dos nanotubos de carbono, tem sido grande o interesse em explorar suas aplicações, e uma delas é a modificação de eletrodos. Muitos trabalhos ilustram as vantagens da aplicação de eletrodos de carbono vítreo modificados com nanotubos de carbono e enzimas. Estes sistemas apresentam resposta amperométrica elevada, com diminuição nos potencias de oxidação ou redução do substrato ou produto enzimático, eliminando a resposta de interferentes. Apresentam bons limites de detecção, melhoras na sensibilidade e estabilidade à medida que oferecem um microambiente favorável à atividade da enzima. Todas estas vantagens tornam interessante o emprego de tais biossensores no monitoramento de pesticidas. Diante da escassez de trabalhos que descrevem esta aplicação, neste trabalho, objetivou-se explorá-la, com ganho em sensibilidade pelo uso dos nanotubos de carbono e em seletividade pelo uso das enzimas. Neste trabalho foi desenvolvido um nanobiossensor para a determinação de carbaril em amostras de tomate. Para isto, os nanotubos de carbono utilizados foram tratados quimicamente e em seguida caracterizados por microscopia eletrônica de transmissão. O eletrodo de carbono vítreo modificado com nanotubos de carbono foi caracterizado eletroquimicamente e por microscopia eletrônica de varredura. A enzima acetilcolinesterase utilizada teve sua atividade catalítica enzimática determinada pelo método espectrofotométrico. O nanobiossensor teve seus parâmetros de operação otimizados e foi utilizado na determinação de carbaril em amostras de tomate. A avaliação de reprodutibilidade de preparação do nanobiossensor apresentou desvio padrão relativo de 4,02%. Os desvios padrão relativos para a repetibilidade e reprodutibilidade de medidas são, respectivamente, 1,18 e 3,27%. Duas amostras de tomate foram dopadas com 0,500 µmol L-1 e 6,00 µmol L-1 de carbaril, e as respectivas recuperações foram de 96,00 e 95,08%. Os limites de detecção e quantificação obtidos com o nanobiossensor foram LD = 8,96 nmol L-1 e LQ = 29,9 nmol L-1. / Since the discovery of carbon nanotubes, a great interest in exploring their applications has raised, being one of those the modification of electrodes. Many works has shown the advantages of applying glassy carbon electrodes modified with carbon nanotubes and enzymes. These systems present elevated amperometric response with decreased potentials of oxidation or reduction of either the substract or the enzymatic product, eliminating the response of interferences as well. Moreover, these systems present good detection limits, as well as sensibility and stability improvements in consequence of a favorable microenvironment for the enzyme action. All these advantages make interesting the employment of such biosensors in pesticides monitoring. Due to the scarcity of works describing this kind of application, the aim of this work is its exploration, focusing on sensibility increasing caused by the use of carbon nanotubes, as well as selectivity increasing caused by the use of enzymes. In this work a nanobiosensor was developed to carbaryl determination in tomato samples. For this, the employed carbon nanotubes were chemically treated before their characterization by transmission electron microscopy. The glassy carbon electrode modified with carbon nanotubes was characterized both electrochemically and by scan electron microscopy. The employed acetylcholinesterase enzyme had its enzymatic activity measured by spectrophotometric means. The nanobiosensor had its operational parameters optimized and it was employed in the determination of carbaryl in tomato samples. The reproducibility of the nanobiosensor preparation was 4.02%. The relative standard deviation for the repeatability and reproducibility were, respectively, 1.18 and 3.27%. Two tomato samples were spiked with 0.500 µmol L-1 and 6.00 µmol L-1 of carbaryl, and their respective recoveries were 96.00 and 95.08%. The detection and quantitation limits obtained with the developed nanobiosensor were, respectively, 8.96 and 29.9 nmol L-1.

Resumo O presente trabalho teve como motivação a medida experimental feita em 2004, reportada na Referência [1], de que nanotubos de carbono dopados com nitrogênio eram sensíveis a gases como a amônia. Essa sensibilidade resulta num aumento da resistência dos tubos quando expostos à amônia, o que os faz bons candidatos para a construção de sensores. Cálculos ab initio foram feitos no programa SIESTA [2] usando DFT [3, 4] na aproximação GGA [5] para estudar a estrutura eletrônica do defeito de nitrogênios proposto pelos experimentais, o qual consiste de uma vacância rodeada por três anéis do tipo piridina. As simulações foram feitas para um nanotubo (5, 5) com aproximadamente 140 átomos. Foi considerada a aproximação de supercélula com condições periódicas de contorno e pseudo-potenciais. A amônia se liga ao defeito mencionado com uma energia de ligação de ?0.26 eV e nesse processo ela se dissocia espontaneamente em um grupo amina (NH2) ligado a um nitrogênio do defeito e um hidrogênio ligado a outro. A transmitância desse sistema foi calculada com o programa TRANSAMPA [6], o qual utiliza o formalismo de funções de Green fora do equilíbrio (NEGF) [6?8] para o cálculo de transporte de cargas. O resultado obtido é que a transmitância do sistema com a amônia ligada é maior do que a referente ao sistema somente com o defeito, o que é contrário à observação experimental. Deu-se início a um estudo sistemático de possíveis defeitos de nitrogênios substitucionais em nanotubos para que fosse possível determinar aquele com a menor energia de formação, o qual seria, por esse motivo, mais abundante numa amostra de tubos dopados. Foram feitos cálculos de energia total para 16 defeitos no tubo (5, 5), 3 no tubo (8, 0) e 3 na folha de grafeno. No tubo (8, 0) foram usados aproximadamente 160 átomos na simulação e na folha de grafeno em torno de 162. O defeito composto por uma divacância rodeada por quatro anéis do tipo piridina se mostrou o mais estável em todos os sistemas, para potenciais químicos do nitrogênio na faixa dos encontrados nos experimentos (?N > 0.5 eV, onde ?N = 0.0 eV é o potencial químico do nitrogênio no N2). A amônia se liga a este novo defeito com uma energia de ligação ligeiramente exotérmica, de ?0.02 eV e novamente se dissocia espontaneamente da mesma maneira que no defeito de três nitrogênios com vacância. A transmitância do sistema ligado, no entanto, se provou menor do que no tubo só com o defeito, o que entra em acordo com o resultado de aumento da resistência provocado pela exposição à amônia observado experimentalmente. / The motivation for the present work was the experimental measure taken in 2004, reported in Reference [1], which showed that carbon nanotubes doped with nitrogens were sensitive to ammonia in such a way as to show a resistance increase when exposed to this gas. This sensitivity makes them good candidates for the fabrication of sensors. Ab initio calculations were made with the SIESTA [2] program using the DFT [3, 4] formalism in the GGA [5] approximation, in order to study the electronic structure of the defect proposed by the experimentalists, composed by three pyridine-like rings surrounding a vacancy. The simulations were made for a (5, 5) nanotube with approximately 140 atoms. The supercell approximation with periodic boundary conditions and norm-conserved pseudopotentials were used. The ammonia molecule binds to the above mentioned defect with an energy of ?0.26 eV. In this process, it dissociates spontaneously into an ammina (NH2) group and a hydrogen, each binding to one of the nitrogens of the defect. The transmittance of this system was calculated with the TRANSAMPA program [6], which uses the non-equilibrium Green?s functions formalism [6?8] to caculate the charge transport. The result we obtained was that the transmittance of the system bound to the ammonia molecule is greater than the one of the unbound system, which is contrary to the experimental observation. We began a systematic study to determine which were the most stable (i.e. the ones with lower formation energy) structures for substitutional nitrogen defects in carbon nanotubes. These calculations were made for 16 defects in the (5,5) tube, 3 in the (8,0) tube and 3 in the graphene sheet. For the (8, 0) nanotube we made use of approximately 160 atoms and for the graphene sheet, around 162. The defect, composed by four pyridine-like rings surrounding two vacancies, was the most stable in the three systems, for nitrogen chemical potentials in the range found in the experiments (?N > 0.5 eV, where ?N = 0.0 eV refers to the nitrogen chemical potential in the N2 molecule). Ammonia binds to this new defect with a slightly exotermic binding energy of ?0.02 eV and dissociates itself in the same way as in the ?three nitrogens plus one vacancy\" defect. The transmittance of the bound system was then again calculated and showed lower values than the ones for the unbound system, which aggrees with the measure of increase in resistance observed by the experimentalists.

Neste trabalho, foi realizado o crescimento de nanotubos de carbono pela técnica de deposição química a vapor (CVD) térmica catalítica, utilizando-se filmes finos de níquel como material catalisador, gás metano (CH4) como fonte de hidrocarboneto e nitrogênio (N2) como gás de arraste. Amostras processadas sobre filmes de Ni de 15 nm de espessura, depositados sobre substrato de óxido de silício (SiO2), com temperatura de processo de 900 ºC e tempo de 15 minutos promoveram uma maior densidade de síntese de nanotubos de carbono, utilizando-se um fluxo na proporção de 2 partes de N2 para 1 parte de CH4. Comprovou-se sua síntese através da visualização de sua morfologia por microscopia eletrônica de varredura (SEM) e microscopia eletrônica de transmissão (TEM), além da extração de seu espectro característico por espectroscopia Raman e espectroscopia de dispersão de raio-X (EDS). Em um segundo estudo, depositaram-se sobre substratos de vidro filmes transparentes e condutores (TCF) à base de nanotubos de carbono de paredes múltiplas (MWCNT) comerciais, pela técnica de dip coating. Para isso, realizou-se a dispersão dos nanotubos sob diversas concentrações em água deionizada (DI) com o auxílio do surfactante dodecil sulfato de sódio (SDS), com posterior funcionalização através do ataque químico por ácido nítrico (HNO3), visando sua aplicação na fabricação de células solares. Foram utilizados os equipamento de quatro pontas e curva corrente x tensão (IV) para caracterização elétrica, transmitância por espectrofotometria para caracterização óptica, SEM para a visualização de sua morfologia e espectroscopia Raman para a análise química de suas estruturas. Valores de resistência de folha de 2x105 W/ e transmitância de 65% foram obtidos nas amostras mais concentradas, com 0,2 mg de nanotubos por ml de água DI. Uma etapa de limpeza em água DI pós deposição foi feita para remoção do excesso de surfactante presente no filme, o que prejudica tanto as características elétricas e ópticas, por ser um dielétrico e não ser transparente. Essa limpeza melhorou o valor de transmitância, porém aumentou a resistência de folha, devido à remoção parcial dos nanotubos presentes no filme, interrompendo em certos pontos a malha que promovia a passagem de corrente elétrica. O ataque químico por HNO3 promoveu a criação de algumas quebras na estrutura do carbono, o que é verificado pelo aumento da banda D, característico da presença de defeitos. / In this work, the growth of CNTs was investigated, using chemical vapor deposition (CVD) thermal catalytic technique, carried out by utilizing thin films of nickel as catalyst material, methane (CH4) as hydrocarbon source and nitrogen (N2) as carrier gas. Samples processed onto 15 nm thick Ni films, deposited on silicon oxide (SiO2) substrates, at a temperature of 900 °C for 15 minutes, promoted a higher density of carbon nanotubes, using a gas mixture at the ratio of 2 parts of N2 and 1 part of CH4. This was verified by analysing the nanotubes morphology by scanning electron microscopy (SEM) and transmission electronic microscopy (TEM) and by the extraction of its characteristic spectrum by Raman spectroscopy and energy dispersive spectroscopy (EDS). In a second study, transparent conductive films (TCF) based on commercial multi-walled carbon nanotubes (MWCNT) were deposited on glass substrates by the dip coating technique. To do so, carbon nanotubes (CNTs) with different concentrations were dispersed in deionized water (DI) with the addition of the surfactant sodium dodecyl sulfate (SDS), and subsequent functionalization through chemical attack by nitric acid (HNO3), aiming their application in solar cell fabrication. The four point probe equipment and current x voltage curve (IV) was used for electrical characterization, transmittance for optical characterization, SEM to visualize their morphology and Raman spectroscopy for chemical analysis of their structures. Sheet resistance values of 2x105 W/ and transmittance of 65% were obtained in the most concentrated samples, with 0.2 mg per ml of nanotubes in deionized water (DI). A cleaning stage in DI water after deposition was taken for removal of surfactant excess in the film, which harms both the electrical and optical characteristics, as it is a dielectric and not transparent. This cleaning improved the transmittance value, but increased the sheet resistance due to partial removal of the nanotubes in the film, interrupting at certain points the mesh of CNTs that promoted the passage of electric current. The chemical attack by HNO3 promoted the functionalization by creating some breaks in the carbon structure, which is checked by the observation of the increasing in D band, which is characteristic of defects.

Carbon nanotube (CNT)/polymer composite sheets can be extremely high strength and lightweight, which makes them attractive for fabrication of mechanical structures. This thesis demonstrates a method whereby smooth, thin CNT/polymer composite sheets can be fabricated and patterned on the microscale using a process of photolithography and plasma etching. CNT/polymer composites were made from CNTs grown using chemical vapor deposition using supported catalyst growth and floating catalyst growth. The composite sheets had a roughness of approximately 30nm and were about 61¼m or 261¼m depending on whether they were made from supported catalyst grown or floating catalyst grown CNTs. The composites were patterned using an oxygen plasma as the etchant and a hard mask of silicon nitride.

This research explores the minimizing of cracks in the fabrication of carbon-infiltrated carbon nanotube (CI-CNT) forests on cylindrical rods for the purposes of creating a CI-CNT coronary stent. It is a continuation of the work begun by Jones [1] and Skousen [2] whose work included the creation of a feasible CI-CNT coronary stent on a planar surface. The current research was performed in two parts: 1) growth on the whole circumference of the rod for ~20mm in length and 2) growth in lines and patterns. Experiments were done on either a 309 or 304 stainless steel rod ~3mm in diameter.The following parameters were used for growth on the whole circumference of the rod: a 80nm alumina diffusion barrier, 1.3 or 7nm of iron as a catalyst layer for CNT growth and a growth time of 1 or 15 min. Cracking is observed on most samples. Area fraction of cracking is shown to be minimized with 7nm of iron and and 1 min growth time. The number of cracks was minimized with the 7nm of iron and 15 min growth time. The height of the CI-CNT forest, which is strongly influenced by the thickness of the iron layer and growth time, is shown to be a possible positive contributor to the area fraction of cracking. Level of carbon infiltration and rate of cooling were also included in the parameters of the study as possible contributors to the amount of cracking however no correlation was found to either of these factors. The second study maintained 80nm of alumina and used 7nm of iron and 10 min of growth time. Line angles parallel, at 7°, at 45° and perpendicular to the axis of the rod and line widths from 109µm to 500µm were studied. Line widths from 500µm to 1090µm were also included in the study of patterned lines perpendicular to the axis of the rod. Cracking was eliminated in the parallel and 7° lines. Cracking in the 45° lines was intermittent and significantly less than the cracking seen on the whole circumference. For the lines perpendicular to the axis, the uncracked arc length was calculated to be an average of 414µm with a standard deviation of 67µm. The uncracked arc length showed no correlation to the line width. A final aspect of this second study observed the cracking in a modification of the planar stent pattern created by Jones. The pattern was modified in to allow for patterning on the rod. The critical dimension maximums of the parent pattern were maintained. The experimental results showed that a continual CI-CNT forest could be fabricated to the minimum expected height of 150µm, a maximum width of 542µm and at the expected angle of 7° with minimal to no cracking.

Heterogeneous catalysts are key materials in research and industry. Herein we study two materials in different stages of development toward being applied as heterogeneous catalysts. First, MoO3SnO2 was synthesized and studied as a catalytic system similar to Sn-beta zeolites. While the Mo-based catalyst did not show similar activity to Sn-beta, it did show interesting reactivity in activating carbonyls and oxidizing organic substrates. Second, a method was developed for grafting amines onto carboxylic acid functionalized carbon nanotubes for CO2 capture. The method was successful for grafting monomer ethylamine groups onto CNT and can be further developed to allow for polymeric amine groups to be grafted.

L’électronique de spin tient une place primordiale dans les technologies de l’information. Un exemple flagrant est le disque dur magnétique à haute densité de stockage intégré aujourd’hui dans la plupart des ordinateurs personnels. D’un point de vue fondamental, les opérations de base comme l’injection, la propagation et la détection de l’information de spin restent néanmoins complexes à réaliser. Des plateformes adaptées à la réalisation de ces tâches élémentaires sont très recherchées. Dans ce contexte, les nanomatériaux carbonés sont très prometteurs. Au cours de ma thèse, je me suis intéressé au transport de spin dans des nanotubes de carbone multi-parois présentant des effets de super-réseaux (Moiré 1D). J’ai également étudié la croissance de barrières moléculaires conformationnelles afin d’optimiser l’injection et la détection de l’information de spin. Je présenterai tout d’abord les caractérisations électriques des dispositifs mettant en évidence des effets de Moirés, identifiés grâce aux simulations effectuées par l’équipe de Jean-Christophe Charlier. Je montrerai ensuite comment la croissance de la couche moléculaire influence le transport en formant une barrière d’injection. Finalement, je présenterai les expériences de magnéto-transport dans ces dispositifs hybrides. La magnétorésistance observée semble indiquer un transport de spin efficace sur des distances au moins de l’ordre du micromètre. Je discuterai particulièrement de l’amplitude, du signe et de la dépendance en tension de la magnétorésistance dans le cadre de modèles standards de transport de spin / Spin electronics holds a key role in information technology. A glaring example is the high-density magnetic hard disk storage built into most personal computers. From a fundamental point of view, basic operations such as injection, propagation and detection of spin information remain nevertheless complex. Platforms adapted to the realization of these basic tasks are highly sought after. In this context, carbon nanomaterials are very promising. During my thesis, I was interested in the transport of spin in multi-wall carbon nanotubes presenting super-lattice effects (Moiré 1D). I have also studied the growth of conformational molecular barriers in order to optimize injection and detection of spin information. I will present first the electrical characterizations of the devices highlighting the effects of Moirés, identified thanks to the simulations carried out by the team of Jean-Christophe Charlier. I will then show how the growth of the molecular layer influences transport by forming an injection barrier. Finally, I will present the experiments of magneto-transport in these hybrid devices. The observed magnetoresistance seems to indicate efficient spin transport over distances of at least a micrometer. I will discuss in particular the amplitude, the sign and the voltage dependence of the magnetoresistance in the framework of standard models of spin transport

Ce travail de thèse est principalement axé sur la création d'un nouveau réacteur biocompatible permettant l'encapsulation et l'étude de bactéries électroactives. Ce compartiment de taille millimétrique, réalisé par coextrusion, est une capsule à coeur liquide possédant une membrane d'hydrogel conducteur. La synthèse de ce bioréacteur a nécessité la formulation d'un hydrogel composite alginate/nanotubes de carbone en deux étapes. Une première étape rapide crée la matrice d'hydrogel par diffusion d'ions divalents dans un mélange Alginate/nanotubes de carbone. Une seconde étape, plus lente, permet la dialyse du tensioactif stabilisant les nanotubes et la création d'un réseau conducteur au sein de l'hydrogel pour des pourcentages massiques de charges supérieurs à 0,5 %. Ce matériau composite présente alors une conductivité macroscopique d'environ 0,1 S/m. Une étude du matériau par voie électrochimique permet entre autres de suivre cinétiquement la connexion des nanotubes de carbone. Des bactéries peuvent adhérer à la surface de cet hydrogel composite. Nous démontrons qu'il est alors possible de mesurer l'électroactivité d'un biofilm bactérien développé sur la paroi interne d'une capsule conductrice. Ce nouveau compartiment biocompatible ouvre la voie vers le développement d'un outil de criblage pour la sélection de bactéries électroactives mais offre également des perspectives innovantes pour la fabrication de piles bactériennes. / This work focuses on the creation of a new biocompatible reactor allowing the encapsulaion and the study of electroactive bacteria. Made by co-extrusion, this millimeter bioreactor is a liquid core capsule with a conducting hydrogel membrane. To create such an object, we formulate a composite hydrogel of alginate/carbon nanotubes in two steps. The first step is rapid and creates the hydrogel matrix by diffusion of divalent ions inside the alginate/carbon nanotubes mix. The second step is slower and permits the dialysis of the surfactant used to stabilize the nanotubes. During this last step, the carbone nanotube network percolates, creating a conducting network in the hydrogel for sufficient nanotube contents (above 0.5 %). This composite material has a macroscopic conductivity around 0.1 S/m. An electrochemical study of this material allows to follow the nanotube connection inside the hydrogel. Bacteria can adhere on this composite hydrogel. Then, we demonstrate that the electroactivity of a biofilm developped on the inner side of the conductive capsule shell can be measured. This new biocompatible and electron-conducting compartment opens the way towards the development of a screening tool for the selection of electroactive bacteria but also brings innovative perspectives in the field of microbial fuel cells fabrication.

Mixed matrix membranes (MMM) offer one potential path toward exceeding the Robeson upper bound of selectivity versus permeability for gas separation performance while maintaining the benefits of solution processing. Many inorganic materials, such as zeolites, metal-organic frameworks, or carbon nanotubes, can function as molecular sieves, but as stand-alone membranes are brittle and difficult to manufacture. Incorporating them into a more robust polymeric membrane matrix has the potential to mitigate this issue. In this work, phase inversion polymer solution processing for the fabrication and testing of asymmetric flat sheet mixed matrix membranes was employed with CVD-derived multiwall carbon nanotubes (MWCNTs) dispersed in a polyethersulfone (PES) matrix. The effect of MWCNT loading on membrane separation performance was examined. Notably, a distinct enhancement in selectivity was measured for several gas pairs (including O2/N2) at relatively low MWCNT loading, with a peak in selectivity observed at 0.1 wt% loading relative to PES. In addition, no post-treatment (e.g. PDMS caulking) was required to achieve selectivity in these membranes. In contrast, neat PES membranes and those containing greater than 0.5 wt.% MWCNT showed gas selectivity characteristic of Knudsen diffusion through pinhole defects. These results suggested that at low loading, the presence of MWCNTs suppressed the formation of surface defects in the selective layer in flat sheet mixed matrix membranes. Additionally, a bench-scale, single-filament hollow fiber membrane spinning line was designed and purpose-built at the University of Kentucky Center for Applied Energy Research (CAER). Hollow fiber membrane spinning capability was developed using polyethersulfone (PES) solution dopes, and the process was expanded to include polysulfone (PSf) as well as mixed matrix membranes. The effects of key processing parameters, including the ratio of bore to dope velocities, the spinning air gap length, and the draw-down ratio, were systematically investigated. Finally, direct hollow fiber analogues to flat sheet mixed matrix membranes were characterized. Consistent with the flat sheet experiments, the mixed matrix hollow fiber membranes showed a local maximum in selectivity at a nominal loading of 0.1 wt.% MWCNT relative to the polymer, suggesting that the pinhole suppression effect introduced by MWCNTs was not limited to flat sheet membrane casting. The development of asymmetric hollow fiber mixed matrix membrane processing and testing capability at the UK Center for Applied Energy Research provides a platform for the further development of gas separation membranes. Using the tools developed through this work, it is possible to further push the frontiers of mixed matrix gas separation by expanding the capability to include more polymers, inorganic fillers, and post treatment processes which previously have been focused primarily on the flat sheet membrane geometry.

The research presented in this doctoral dissertation aimed to improve knowledge on methods to evaluate exposures to carbon-containing nanomaterials and to develop optimized respiratory filters properties to protect workers from these exposures while minimizing discomfort due to breathing resistance. In the initial study, a novel laboratory-based system generated aerosols of four carbon-containing powders (carbon black, a small-diameter (< 8 nm) multi-walled carbon nanotube (MWCNT), a large-diameter (50-80 nm) MWCNT, and a nickel-coated MWCNT) to evaluate the effectiveness of NIOSH Method 5040 for measuring masses as low as 1 μg. A targeted mass of a powder ranging from 1 to 30 μg was deposited on filters for gravimetric and elemental carbon (EC) analysis. The gravimetric mass was compared to the EC mass, and a regression model developed for each powder type. Additionally, the limit of detection (LOD) of the NIOSH Method 5040 for each powder type was determined. The regression models had significant slopes relative to zero for all powder types with all but carbon black demonstrating a statistical difference between the two methods. The LOD of NIOSH Method 5040 ranged from 4.5 for small-diameter MWCNTs to 31.8 μg for nickel-coated MWCNTs. Assuming a sample flow rate of 4.2 L/min and an 8-hour sample duration, the concentration-based LOD for NIOSH Method 5040 ranged from 2.2 μg/m3 for small-diameter MWCNTs to 15.8 μg/m3 for nickel-coated MWCNTs. These results indicate the analysis of EC is affected by the structure and elemental content of the CNTs. Additionally, based on the LOD determined for each powder type, the method may not be sufficient to assess exposures at and below the recommended exposure limit accurately without sampling durations longer than 8 hours. A second study used a laboratory-based system to evaluate an aethalometer response to carbon-containing nanomaterials including carbon black and MWCNTs. Concentrations ranging from 1 to 20 μg/m3 were generated to evaluate the device at concentrations expected in occupational settings. The concentration of the aerosol was measured by an aethalometer alongside a sample collected for EC analysis using NIOSH Method 5040. Additionally, NIOSH Method 7300 was used to determine the concentration of nickel during trials with a nickel-coated MWCNT to determine if the method along with the aethalometer can be used to assess metal-coated MWCNTs. A regression model was developed for each powder type, and the slopes for each were significant relative to zero. The LOD of the aethalometer ranged from 0.56 μg/m3 for nickel-coated MWCNTs to 7.2 μg/m3 for small-diameter MWCNTs. These results indicate the response of the aethalometer may be affected by particle structure and elemental content. NIOSH Method 5040 performed better than the aethalometer for all powder types except the nickel-coated MWCNT. Additionally, based on the LOD determined for each powder, an aethalometer may not be able to assess low-level exposures. In the third study, a mathematical model was used to predict the particle penetration and pressure drop of respirator filters with varying filter thickness, fiber diameter, solidity, and electrostatic charge. Particle penetration was determined experimentally for two different commercially available respirator filters against a sodium chloride aerosol using a scanning mobility particle sizer (SMPS). Optimized filter designs were developed using the model to minimize the pressure drop by adjusting the filter depth, fiber diameter, and solidity of the filter. The model and experimental data were used to maintain a 5% maximum penetration against nanoparticle exposures while minimizing breathing resistance. Model results indicated electrostatic charging played a significant role in improving collection efficiency of respirator filters while not increasing the breathing resistance of the filter. Filter thickness and solidity also played a key role in minimizing breathing resistance. Pressure drop decreased with decreasing solidity, however, the filter depth increased to maintain the collection efficiency of the filter. This increase in filter depth introduced a decision point of determining the practical implications of increased filter thickness on the end user. Filter depth increases dramatically as the solidity decreases below 0.20. The breathing resistance that corresponds to this design is heavily dependent on the face velocity and electrostatic charge of the filter. The electrostatic charge should be maximized during filter production as this was the dominant collection method for nanoparticle aerosols.