Christopher Harrison

Low-power microwave-generated helium microplasma for molecular and atomic spectrometry

Atmospheric pressure microplasmas are a promising technology for low-power optical emission spectroscopy for chemical detection. In this work, we examine a microstrip split-ring resonator (MSRR) discharge operating at 1.8 GHz in helium as an excitation source. The source can sustain a plasma with as little as 0.2 W of microwave power, and can be operated continuously with no electrode damage. With a compact 156 mm focal length spectrometer system, we determined detection limits on the order of 1 ppm for methane, n-butane, carbon dioxide, and hydrogen sulfide with plasma powers of both 0.3 and 1.0 W. With appropriate choice of the monitored emission lines, the detection system is robust to small additions of air. We also demonstrate the applicability of the MSRR as a sensor for gas chromatography.

A MEMS sensor for the measurement of density-viscosity for oilfield applications

We present a sensor fabricated with MEMS (Micro-Electro-Mechanical Systems) technology that upon immersion quickly measures fluid density and viscosity. The operational principal involves the influence of the fluid on the resonance frequency and quality factor of a vibrating plate oscillating normal to its plane. By performing measurements in liquids over a wide range of temperature (20 to 150 C) and pressure (0.1 to 75 MPa), we have demonstrated a maximum inaccuracy in our density and viscosity measurements of approximately +/- 1.5 % and +/- 10 % respectively, for fluids with densities between (0.6 to 1.5) g/cc and viscosities between (0.4 to 100) cP. Such measurements are required to determine the economic feasibility of recovering hydrocarbon from subterranean strata. There are numerous examples in the literature of sensors fabricated by the methods of MEMS that are claimed to measure both density and viscosity of fluids, but in most cases, the accuracy of such sensors is not been demonstrated in a wide range of fluids and moreover, their use in non-laboratory environments has not been proven.1,2,3 Here we show that it is possible to design and package a sensor that can function with high accuracy in extreme environments while providing useful information.

A microfluidic MEMS sensor for the measurement of density and viscosity at high pressure

We present a sensor fabricated with MEMS (Micro-Electro-Mechanical Systems) technology that quickly measures fluid density and viscosity. This sensor is fabricated inside of a microfluidic channel through which the fluid to be measured passes. The operational principal involves the influence of the fluid on the resonance frequency and quality factor of a vibrating plate oscillating normal to its plane. By performing measurements in liquids we have demonstrated operability in fluids with densities between (0.6 to 1.5) g/cc and viscosities between (0.4 to 100) cP. Such measurements are required to determine the economic feasibility of recovering hydrocarbon from subterranean strata. There are numerous examples in the literature of sensors fabricated by the methods of MEMS that are claimed to measure both density and viscosity of fluids, but in most cases, the accuracy of such sensors is not been demonstrated in a wide range of fluids and moreover, their use in non-laboratory environments has not been proven.1,2,3 Here we show that it is possible to design and package a sensor that can function with high accuracy in extreme environments while providing useful information.