Fundamentals and applications of microplasma sources : Actuating, Sensing, and Nonlinearly Approximating

Sammanfattning: The research presented in this thesis covers a wide range of applications for, and integrations of, a stripline split-ring resonator (SSRR) microplasma source. Common throughout the presented works is the always present, but sometimes secondary, focus on analyzing the light and matter that is emitted as gas is flowed through theplasma of the SSRR.When evaluated as a heater in a cold-gas microthruster intended for attitude adjustment and orbit maintenance of miniaturized satellites, the plasma was shown to be a more efficient than two modes of resistive heating in improving the specific impulse of the thruster. Furthermore, the ionized exhaust plume of the thruster was used to derive a novel method of estimating its efficiency. In further analysis of the plasma parameters, correlations between supplied power, ion density, and thrust efficiency were uncovered and verified by Langmuir probe measurements.In subsequent experiments, the use of the SSRR as a residual gas analyzer was explored, first by comparing different classes of regression methods for determining gas species concentrations from emitted UV-NIR spectra from the plasma. In a second study, the wide range spectrometer was replaced with an optical filter and a photodetector, in a differential gas sensor setup where the regression methods were replaced with peak intensity differentiation.With the SSRR’s prospects as a gas sensor confirmed, further work focused on integrating it in a transcutaneous blood gas monitoring (TBM) system. To address the shortcomings of existing systems, a series of three studies covered the fabrication and evaluation of (i) A soft gas-collecting patch that, with its accompanying microfluidics, transported the gas that permeates the skin to the sensor, (ii) A novel fabrication technique to integrate an electrical interface in the bulk of the patch, and a prototype out-of-plane skin heater, and (iii) A theoretical model that related the transcutaneous gas composition to blood gas concentration based on a computational fluid dynamics model. Finally, the sensor and gas collector were integrated in a fully functional TBM system.In conclusion, the thesis explores the use of an SSRR throughout the three cornerstone configurations of microsystem technology: as an actuator for microsatellite propulsion, as a sensor for gas measurements, and integrated in a system for blood gas monitoring.