Engineering Commons^™

Analytical Modeling Of A Novel Microdisk Resonator For Liquid-Phase Sensing: An All-Shear Interaction Device (Asid), Mohamad Sadegh Sotoudegan

Dissertations (1934 -)

Extensive research on micro/nanomechanical resonators has been performed recently due to their potential to serve as ultra-sensitive devices in chemical/biosensing. These applications often necessitate liquid-phase sensing, introducing significant fluid-induced inertia and energy dissipation that reduces the resonator’s performance. To minimize the detrimental fluid effects on such devices, a novel microdisk resonator supported by two tangentially-oriented, axially-driven “legs” is investigated analytically and effects of the system parameters on the resonator/sensor performance are explored. Since the device surface vibrates primarily parallel to the fluid-structure interface, it is referred to here as an “all-shear interaction device,” or ASID. Analytical modeling of the ASID …

Investigation Of The Use Of A Plasticizer-Polymer Sensor Coating With Improved Long-Term Stability In The Liquid Phase, Laura Jeanne Alderson

Master's Theses (2009 -)

Benzene is one of the volatile organic compounds present in crude oil and gasoline. Leakage from underground storage tanks or hazardous waste sites can introduce benzene contamination into nearby groundwater. Benzene is a known carcinogen and its exposure is limited by the Environmental Protection Agency to 5 parts per billion (ppb) in drinking water. Early, accurate detection of the presence of benzene contamination in groundwater supplies is extremely important. Shear horizontal surface acoustic wave (SH-SAW) devices with a chemically sensitive coating can be used for the detection of volatile organic compounds in liquid, such as BTEX (benzene, toluene, ethylbenzene and …

Thermal Microfluidic Devices; Design, Fabrication And Applications, Benyamin Davaji

Dissertations (1934 -)

This thesis investigates the thermal actuation and temperature measurement methods in microfluidic devices. We designed and fabricated microfluidic devices with various functionalities such as: bio sensing, particle counting, microscale calorimetry, and cellular temperature measurement. All of these functionalities use thermal measurement methods. When quantitative measurements are required, the label-free nature of thermal measurement methods, along with its simple readout, make it a powerful candidate for lab on a chip and bio sensing/detection applications. In this work, thermal measurement methods are used to characterize bio-samples, measure concentrations, study thermal responses, and even perform particle cytometry. However, thermal measurement methods are known …

Characterization Of Plasticizer-Polymer Coatings For The Detection Of Benzene In Water Using Sh-Saw Devices, Jude Coompson

Master's Theses (2009 -)

Benzene is a constituent component of crude oil that has been classified as a carcinogen by the EPA with a maximum contamination level (MCL) of 5ppb in drinking water. However, of the aromatic compounds, benzene has one of the lowest polymer-water partition coefficients using commercially available polymers as sensor coatings, resulting in poor limits of detection. This work investigates new coating materials based on polymer/plasticizer mixtures coated onto a shear horizontal surface acoustic wave (SH-SAW) sensor to detect benzene in water. There are many polymers which are unavailable for use as a sensing polymer due to their glassy nature. The …

Surface Acoustic Wave (Saw)-Based Gas Flow Sensor, Nisar Ahmad

Dissertations (1934 -)

There has been a growing interest in using SAW devices for sensing various physical parameters such as pressure, acceleration, temperature, and gas. The current research has been undertaken to derive a model of a SAW-based gas flow rate sensor, using the principle of heat transfer with the flow of gas. It consists of a SAW delay line fabricated on a suitable substrate and a thin film heater to heat the SAW device to a suitable temperature above the ambient. The delay line is connected in the feedback loop of an rf-amplifier resulting in a delay line stabilized SAW oscillator. When …

Analysis Of The Detection Of Organophosphate Pesticides In Aqueous Solutions Using Polymer-Coated Single Idt Sensors, Michael J. Mccarthy

Master's Theses (2009 -)

The single interdigital transducer (IDT) device was investigated as a micro-chemical sensor for the detection of organophosphates compounds in aqueous solutions. The compounds of interest are: parathion, parathion-methyl, and paraoxon. The polymers used as a partially-selective coating for the direct detection of these compounds are 2,2'-diallylbisphenol A- 1,1,3,3,5,5-hexamethyltrisiloxane (BPA-HMTS) and polyepichlorohydrin (PECH). BPA-HMTS is synthesized here at Marquette University. The measurement of interest for the single IDT is the change radiation resistance. The radiation resistance represents the energy stored in the propagating acoustic wave. As analyte absorbs into the polymer coating, changes in the film's properties will undergo resulting in …

Chemically Sensitive Polymer Coatings For Sh-Surface Acoustic Wave Sensors For The Detection Of Benzene In Water, Robert Lenisa

Master's Theses (2009 -)

Polymer-coated shear horizontal surface acoustic wave (SH-SAW) sensors are investigated for the detection of benzene in aqueous samples. The SH-SAW sensors using three-layer geometry have a single polymer sensing layer which absorbs the analyte and interacts with the surface wave. Several polymers are identified as potential improvements over current sensing films based on glass transition temperature and Hildebrand solubility parameter. The polymers investigated in this work include poly (methyl acrylate) (PMA), poly (butyl acrylate) (PBA), poly (ethylene co-vinyl acetate) (PEVA), bisphenol-A poly (dimethylsiloxane) (BPA PDMS), and bisphenol-A poly (hexamethyltrisiloxane) (BPA HMTS).

The polymers are spin coated on a lithium tantalate …

Detection Of Specific Biological Antigens Using Ac Electrochemical Impedance Spectroscopy, Darrel Angelo Mazzari

Dissertations (1934 -)

When certain antigens are present in our environment, a rapid, on-site, accurate, selective, and repeatable detection method can be invaluable in preventing illness or saving lives. Rapid detection of these antigens is important to avert spreading infections.

Currently, capturing a sample and sending it to a laboratory can take weeks to get results, which can be much too long. Conventional sensing methodologies include various electrical measurements as capacitive, potentiometric, piezoelectric, surface plasmon resonance (SPR), and quartz crystal microbalance (QCM). Of particular power and interest is Alternating Current (AC) Electrochemical Impedance Spectroscopy (EIS) which provides for the characterization of the electrical …