Ultrafine particle emissions in motor-vehicle exhaust are associated with cardiopulmonary health impacts and increased mortality. The emission, evolution, and exposure-uptake of these particles, one hundred nanometers and smaller in diameter, are fundamentally quantified by the number concentration as a function of particle size. Ultrafine particle number distributions are widely varying and fast changing as they are strongly influenced by local environmental conditions and variation in vehicle operation and maintenance. Research and regulation to quantify and control such emissions rely on measurement of the number distribution of ultrafine particles in vehicle exhaust and by the roadside. Instruments to make such measurements are commercially available, but they are expensive, non-portable, and have slow response times. A new instrument, the NanoAPA, is being developed for these in-situ applications as an inexpensive, portable, and real-time instrument. The instrument is designed to perform ultrafine particle sizing and counting through electronic control of a microfabricated device that charges sampled airborne particles with a corona ionizer and then incrementally size-separates, collects, and counts the number of particles in the aerosol. The focus of this thesis was the development and characterization of the smallest device known that can perform these sizing and counting functions. The device miniaturizes a classical instrument from the aerosol field, the double-condenser of Whipple (1960) used for the sizing and counting of atmospheric ions, into a microfabricated device designed to utilize voltage-and-flowrate-variable electrophoresis to measure ultrafine particle aerosols. Performance characterization of the microfabricated device required development of an apparatus for the generation and conditioning of aerosols appropriate to this application. This Standard Aerosol apparatus was demonstrated to produce repeatable, temperature and humidity stable, charge-neutral, monodisperse exhaust-analog aerosols of particles 10 to 100 nanometer in diameter. The microfabricated device was characterized with the Standard Aerosol apparatus for the operating conditions of 0.1 to 1.5 liter per minute flow rate and 0 to 3000 volt separator voltage. Results of the characterization demonstrated effective selection and collection of solvent droplets in the diameter range 10-100nm. The selection and collection results for engine-exhaust analog particles were inconclusive, likely due to particle re-entrainment. Repeatable measurements of particle number proved elusive, likely due to electrical field interference, the limited particle concentration obtainable from the Standard Aerosol apparatus, and signal-to-noise and temporal stability issues with the electrometer electronics. Recommendations are made for approaches likely to overcome these issues.

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Electrospray Ionization (ESI) is a technique that permits the soft ionization of large proteins and biomolecules without fragmenting them, which allows them to be characterized via Mass Spectrometry (MS). It has the potential of permitting the identification of transient intermediate products in biological processes in situ, which would provide great insight to researchers in the growing fields of proteomics and metabolomics. However, this application presents a technical challenge in that most relevant biochemistry occurs in aqueous solutions with high salt content, which makes successful identification of analytes by ESI-MS difficult. This thesis presents the design, fabrication, and characterization of a microfabricated dialysis module that could alleviate this issue by desalting samples inline between sampling and electrospraying interfaces. Its small volume (~10 nL) minimizes sample transit time and, thus, optimizes ESI-MS analysis temporal resolution. A preliminary analytical model of dialysis elucidates the key performance parameters and sets the guidelines for consideration in its design. The device is then microfabricated in a cleanroom environment using techniques that have been well established by the microelectronics industry such as E-beam evaporation and Reactive Ion Etching. The system efficiency is demonstrated experimentally by assessing its salt removal effectiveness as a function of sample residence time. Mass spectrometry analyses of proteins in solutions with high salt content further corroborate its performance.

This work presents microfabricated microelectrodes, capable of quantitative analysis in molten salt (MS). MSs are an electrolytic medium of growing interest, especially in the area of nuclear reprocessing. However, designing sensors for a MS-based nuclear reprocessing system is a challenge, owing to the usually corrosive nature and high operating temperatures (typically 450 - 500◦C) of MS. Microelectrodes are well placed as sensors, with numerous advantages over macro-scale electrodes. As a consequence, there have been previous attempts to utilise microelectrodes inMS. However, these have not been successful and all have suffered disadvantages inherent in traditional microelectrode manufacturing. The microelectrodes presented in this work were produced using standard microfabrication techniques and characterised in MS. An analysis of failure mechanisms guided a systematic study of material combinations. This resulted in a sensor, which is capable of delivering quantifiable electrochemistry in MS. However, the lifetime and yield of the sensor were determined to only be 46% and 1.4 hours respectively. Further investigation of the microelectrode failure mechanisms guided several layout changes to the microelectrode design. By reducing critical area, where defects or pinholes could form, these resulted in improvements in performance. This increased the yield to 65%, while the average lifetime increased up to 45 hours. Test structures were designed to investigate the causes of the continued microelectrode failures and identified shorting between the electrode metal and silicon substrate. This suggests the existence of defects in the underlying insulator are the cause of the 35% of microelectrodes which never functioned. Separate test structures suggested the lifetimes of the microelectrodes could also be improved by removing the need for a metal adhesion layer. Tantalum has been suggested as a replacement electrode metal and a proof of concept study demonstrated the feasibility of employing thin film tantalum as an electrode metal in LKE. Using this technology as a platform, several proof-of-concept microelectrode designs are also presented: liquid microelectrodes, microelectrode arrays, and a nanoelectrode. These are targeted at specific sensing applications, and provide an expanded spectrum of measurements in MS.

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The objective of this research is to design, fabricate, and demonstrate a microfabricated monolithic ion trap for applications in quantum computation and quantum simulation. Most current microfabricated ion trap designs are based on planar-segmented surface electrodes. Although promising scalability to trap arrays containing ten to one hundred ions, these planar designs suffer from the challenges of shallow trap depths, radial asymmetry of the confining potential, and electrode charging resulting from laser interactions with dielectric surfaces. In this research, the design, fabrication, and testing of a monolithic and symmetric two-level ion trap is presented. This ion trap overcomes the challenges of surface-electrode ion traps. Numerical electrostatic simulations show that this symmetric trap produces a deep (1 eV for 171Yb+ ion), radially symmetric RF confinement potential. The trap has an angled through-chip slot that allows back-side ion loading and generous through laser access, while avoiding surface-light scattering and dielectric charging that can corrupt the design control electrode compensating potentials. The geometry of the trap and its dimensions are optimized for trapping long and linear ion chains with equal spacing for use with quantum simulation problems and quantum computation architectures.

When a temperature differential is applied across a semiconductor, a thermal voltage develops across it in response. The ratio of this thermal voltage to the applied temperature differential is the Seebeck coefficient, a transport coefficient that complements measurements of electrical and thermal conductivity. The physical interpretation of the Seebeck coefficient is the entropy per charge carrier divided by its charge and is hence a direct measurement of the carrier entropy in the solid state. This PhD thesis has three major outcomes. The first major outcome is a demonstration of how the Seebeck coefficient can be used as a tool to quantify the role of energetic disorder in organic semiconductors. To this end, a microfabricated chip was designed to perform accurate measurements of the Seebeck coefficient within the channel of the active layer in a field-effect transistor (FET). When measured within an FET, the Seebeck coefficient can be modulated using the gate electrode. The extent to which the Seebeck coefficient is modulated gives a clear idea of charge carrier trapping and the distribution of the density of states within the organic semiconductor. The second major outcome of this work is the observation that organic semiconducting polymers show Seebeck coefficients that are temperature independent and strongly gate voltage modulated. The extent to which the Seebeck coefficient is modulated in the polymer PBTTT is found to be larger than that in the polymer IDTBT. Taken together with conventional charge transport measurements on IDTBT, the voltage modulated Seebeck coefficient confirms the existence of a vanishingly small energetic disorder in this material. In the third and final outcome of this thesis, the magnitude of the Seebeck coefficient is shown to be larger for organic small molecules as compared to organic polymers. The basis for this is not yet clear. There are reports that such an observation is substantiated through a larger contribution from vibrational entropy that adds to the so called entropy-of-mixing contribution so as to boost the magnitude of the Seebeck coefficient in organic small molecules. As of now, this remains an open question and is a potential starting point for future work. The practical implications of this PhD thesis lie in building cost-effective and environmentally friendly waste-heat to useful energy converters based on organic polymers. The efficiency of heat to energy conversion by organic polymers tends to be higher than that for conventional semiconductors owing to the presence of narrow bands in organic polymer semiconductors.

Desorption Electrospray Ionization Mass spectrometry Imaging (DESI-MSI) is an area of great interest and a promising tool in the field of chemical imaging. It is a powerful, label-free technique, which can determine, map and visualize different molecular compounds on a sample surface. The amount of information acquired in a single DESI-MSI experiment is enormous compared to other techniques, as it can simultaneously detect different compounds with their spatial distribution on the surface. The experiment can be used to produce two-dimensional and three-dimensional images. Chapter 2 focuses on the design and optimization of the setup for performing DESI-MS imaging on various substrates. The proposed setup was tested for its lateral spatial resolution. To provide proof-of-concept of the design, preliminary tests were performed to generate images from commercial thin layer chromatographic plates and photographic paper. Chapter 3 focuses on demonstrating the compatibility of novel microfabricated Thin Layer Chromatography plates (M-TLC plates) for detection with DESI-MSI.