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With a population both increasing in number and age, comes a need for new diagnostic tools in the healthcare system, capable of diagnosing and monitoring multiple disorders in a cheap and effective way to provide personalised healthcare. Multiplex label-free biosensors have the potential to rejuvenate the current system. This thesis details the assessment of an ‘in house’ built labelfree array screening technology that has potential to be a point-of-care diagnostic for personalised medicine – the Array Reader. The performance of the Array Reader platform is considered in detail and optimised for both antibody and protein screening arrays. A Global Fit protocol is developed to extract kinetic constants for all protein-protein interactions, assuming a Langmuir adsorption binding model. Standard operating procedures are developed to provide optimised dynamic range, sensitivity, reproducibility and limit of detection of immuno-kinetic assay. A new antibody bio-stack signal amplification strategy is formed, improving the detection limit 60-fold. As a consequence, the bio-stack resulted in a novel method for determining the plasmon field penetration depth, defining the assay sensing volume at the nanoparticle surface. Antibody screening arrays were investigated with an IgG quantification assay to determine total IgG content from serum samples. It relied on the ability of protein A/G to bind antibodies via the Fc region. Specific antigens were used to measure the binding properties of the antibody Fab region. By characterising both regions, we have gained insight into the overall ability of an antibody to trigger an immune response. Protein screening assay were investigated targeting C-reactive protein (CRP), a marker of inflammation. The assays performance characteristics compared favourably with clinically used CRP assays. Finally, an antibody screening array was developed to assess the efficacy of a vaccine against Yersinia pestis in a non-human primate model. The vaccine screening array is an excellent example of the versatility of the platform and just one of many possible applications for the future.

Low temperature plasmas (LTP) can produce chemically rich environments at close to room temperature at ambient pressures. LTP is able to deliver reactive oxygen and nitrogen species (RONS) in a non-destructive, beneficial way to even extremely heat sensitive surfaces. This provides a unique condition that enables plasma generated RONS to regulate key biological pathways by causing chemical and physical changes in living matter and has the potential to underpin new medical therapies for a range of illnesses. The goal of my project is (i) to study the production and diffusion of hydrogen peroxide species, a key RONS with biological impact, generated by interaction of an atmospheric pressure plasma jet with a gelatin gel used as a skin tissue model in this work and (ii) study the surface charge deposition by a plasma jet on a dielectric target. Surface charges are an important parameter to monitor since it influences the dynamics of the discharge propagation on the surface and charged species at biological interfaces are suggested to play a possible role in plasma induced biological effects. Plasma – Hydrogel interaction The interaction of He atmospheric pressure plasma with Gelatin hydrogel (10% w/v), a model for skin is investigated and in particular generation of reactive oxygen species (ROS) and penetration of ROS in the hydrogel. The diffusion of ROS (in particular H2O2) in gelatin hydrogel is analyzed by implementing two diffusion analysis approaches; diffusion cell experiments and experiments in which a droplet containing H2O2 is placed on top of a hydrogel. Furthermore, the flux of plasma generated H2O2 species both in liquid medium (distilled water) and gelatin hydrogel are determined in this study. KI – Starch is used as an indicator to observe and quantify the diffusion of H2O2 in the gel. Diffusion profiles of H2O2 droplets are directly compared to those generated by interaction of plasma. H2O2 droplet diffuses through the gelatin sample over time, giving rise to a deep blue colored diffusion profile. On the other hand, the helium generated plasma produces a surface level color change. In order to understand the surface level color change patterns experiments were performed by using ‘He + H2O’ and ‘He + O2’ as the feed gas in our plasma jet to investigate the influence of plasma produced H2O2, OH and O3 species respectively. The flux of plasma (He + 0.81% H2O) generated H2O2 species in gelatin hydrogel is found to be 1013-1014 molecules/(s·mm2). This is smaller than for the same plasma interacting with liquid H2O. The flux of plasma generated H2O2 species in humid helium distilled water was found to be (5.1 ± 0.3) × 1014 molecules/(s·mm2) which is 2 times higher than (2.5 ± 0.3) × 1014 molecules/(s·mm2) as measured for dry helium. The penetration depth for plasma (~ 2 mm) in gelatin hydrogel on a 20 min time scale mainly due to H2O2 diffusion, while other species like O3 and OH lead to interfacial effects. Plasma induced electric field and surface charge distribution The aim of this study was to determine the surface charge distribution induced by an RF driven atmospheric pressure plasma jet impinging on a glass substrate. The goal of my work was to augment the experimental data previously obtained with simulations, and calibration measurements. This study includes a validation measurement of the used approach in a Laplacian electrostatic field in a similar geometry as in the plasma experiment. A good correspondence of the experimental and simulation results for both negative (t = 9.48 µs) peak and positive (t = 9.52 µs) peak of the RF pulse were obtained by assuming a Gaussian surface charge distribution function. The instantaneous positive surface charge distribution had a peak density of σpos = 0.05 nC cm−2 and the corresponding full width at half maximum (FWHM) of the surface charge distribution was found to be ~1.5 mm. The instantaneous negative surface charge distribution had a peak density of σneg = 0.06 nC cm−2 and the FWHM of the surface charge distribution was found to be ~2 mm. The diameter is similar to the nozzle diameter of the jet and suggest minimal spreading of the jet on the glass surface. The results obtained in this work contribute to a better understanding of the interaction of plasma jets with biological and dielectric substrates and will help in the development of LTP applications that would benefit by using plasma to effectively ‘drive’ ROS into biological substrates and assess the role of surface charging on plasma-induced biological effects.

The betavoltaic battery is a type of micro nuclear battery that harvests beta emitting radioactive decay energy using semiconductors. The literature results suggest that a better model is needed to design a betavoltaic battery. This dissertation creates a comprehensive model that includes all of the important factors that impact betavoltaic battery output and efficiency. Recent advancements in micro electro mechanical systems (MEMS) necessitate an onboard miniaturized power source. As these devices are highly functional, longevity of the power source is also preferred. Betavoltaic batteries are a very promising power source that can fulfill these requirements. They can be miniaturized to the size of a human hair. On the other hand, miniaturization of chemical batteries is restricted by low energy density. That is why betavoltaics are a viable option as a power source for sophisticated MEMS devices. They can also be used for implantable medical devices such as pacemakers; for remote applications such as spacecraft, undersea exploration, polar regions, mountains; military equipment; for sensor networks for environmental monitoring; and for sensors embedded in bridges due to their high energy density and long lifetime (up to 100 years). A betavoltaic battery simulation model was developed using Monte Carlo particle transport codes such as MCNP and PENELOPE whereas many researchers used simple empirical equations. These particle transport codes consider the comprehensive physics theory for electron transport in materials. They are used to estimate the energy deposition and the penetration depth of beta particles in the semiconductors. A full energy spectrum was used in the model to take into account the actual radioactive decay energy of the beta particles. These results were compared to the traditional betavoltaic battery design method of estimating energy deposition and penetration depth using monoenergetic beta average energy. Significant differences in results were observed that have a major impact on betavoltaic battery design. Furthermore, the angular distribution of the beta particles was incorporated in the model in order to take into account the effect of isotropic emission of beta decay. The backscattering of beta particles and loss of energy with angular dependence were analyzed. Then, the drift-diffusion semiconductor model was applied in order to estimate the power outputs for the battery, whereas many researchers used the simple collection probability model neglecting many design parameters. The results showed that an optimum junction depth can maximize the power output. The short circuit current and open circuit voltage of the battery varied with the semiconductor junction depth, angular distribution, and different activities. However, the analysis showed that the analytical results overpredicted the experimental results when self-absorption was not considered. Therefore, the percentage of self-absorption and the source thickness were estimated using a radioisotope source model. It was then validated with the thickness calculated from the specific activity of the radioisotope. As a result, the battery model was improved significantly. Furthermore, different tritiated metal sources were analyzed and the beta fluxes were compared. The optimum source thicknesses were designed to increase the source efficiencies. Both narrow and wide band gap semiconductors for beryllium tritide were analyzed.

Finding more efficient ways of exploring the doping phase diagrams of high temperature superconductors as well as probing the fundamental properties of these materials are essential ingredients for driving the discovery of new materials. We use a doping technique involving gating with ionic liquids to systematically and continuously tune the Tc of superconducting La2CuO4+x thin films. We probe both the transport properties and the penetration depth of these samples and find that Homes scaling, lambda^-2 ~ sigma*Tc, is obeyed, consistent with these materials being in the dirty limit. This result is independent of the precise mechanism for the gating process as all of the parameters of the scaling relationship are determined by direct measurements on the films.

Slurry wall is a geotechnical engineering application to control the migration of contaminants by retarding groundwater flow. Sand-bentonite slurry walls are commonly used as levees and containment liners. The performance of bentonite slurry in sand-bentonite slurry walls was investigated by studying the rheological properties of bentonite suspensions, the penetration length of bentonite slurry into clean sand, and stability of the trench under in-situ hydraulic gradients. In this study, the rheological parameters of bentonite suspensions were measured at various bentonite fractions by weight from 6 to 12% with 0-3% of sodium pyrophosphate; an ionic additive to control the rheological properties of the bentonite slurries. The penetrability of the bentonite slurries through Ottawa sand was studied by injecting the slurries into sand columns at different bentonite fractions. The injection tests were performed with the permeameters having different diameters to eliminate any bias on test results due to the different size of permeameter. An empirical correlation for predicting the penetration length of bentonite slurry based on apparent viscosity, yield stress, effective particle size, relative density, and injection pressures was updated by taking into account the effects of the permeameter diameter size. Moreover, the stability of sand-bentonite slurry walls was inspected by studying the hydraulic performance of sand permeated with bentonite suspensions under increasing hydraulic gradients. The critical hydraulic gradient at which washing out of bentonite suspensions is initiated was examined. For specimens with bentonite contents less than the threshold value, the flow occurred through the sand voids and minimal washing out occurred. On the other hand, when the bentonite content was high enough to fill up all the void space between the sand particles, the flow was controlled by the clay void ratio. In this case, washing out did occur with increasing gradients accompanied by an increase in hydraulic conductivity. Accordingly, a relation between the yield stress of bentonite suspensions and the critical hydraulic conductivity was developed.

Superfluid density ns(T) [∝ λ-2(T) and λ is the penetration depth] is a fundamental parameter in superconductivity. In my Ph. D. work, by measuring the complex sheet conductivity of thin superconducting films in a two-coil mutual inductance apparatus, both the amplitude and the temperature dependence of superfluid density are determined in various superconducting systems. This is then used to understand various physics like pairing symmetry, and thermal and quantum critical fluctuations in low dimensions, in the following materials: (1)Bi2Sr2CaCu2O8+x (Bi-2212) films: A wide range of doping is achieved by pulsed laser deposition (PLD) and sputtering with transition temperatures (Tc) ranging from 80K near optimal doping to 6K for severely underdoped ones. In moderately underdoped Bi-2212 films with Tc > 50K, Beresinskii-Kosterlitz-Thouless (BKT) transition, an evidence of 2-D thermal critical behavior, is observed by a sharp downturn of superfluid density near Tc. This is consistent with the extremely anisotropic nature of Bi-2212. However, this thermal critical behavior disappears for severely underdoped Bi-2212 with Tc < 45K. At this regime, Tc scales linearly with the superfluid density λ-2(0). These two results are the evidence of the 2-D quantum critical behavior in deeply underdoped Bi-2212 near a quantum critical point (QCP). (2) Iron-based Ba(CoxFe1-x)2As2 films near optimal doping: At low temperatures, superfluid density varies like λ-2(T) ∝ T2.55, consistent with a novel s± pairing symmetry with significant interband scattering between two different Fermi surfaces. Overall, λ-2(T) can be fit by a dominant small BCS-like superconducting gap 2Δ/kBTc ~2.1. The possible bigger gap vanishes and this may due to its strong intraband scattering. (3) Ultrathin NbN and Pb films: sharp downturns, which clearly deviate λ-2(T) from its standard BCS theory predictions, are observed in these ultrathin films near Tc. They are associated with two dimensional thermal critical fluctuations and are clear evidences of Beresinskii-Kosterlitz-Thouless (BKT) transitions. However, it seems that downturns always occur earlier than what XY model predicts. This means that the vortices are energetically easier to create, and the reason behind this finding is still unclear.