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Full-Text Articles in Engineering Science and Materials
Monitoring Co Concentration In Fuel Cells Using Microcantilever Sensors, Tugba Demir
Monitoring Co Concentration In Fuel Cells Using Microcantilever Sensors, Tugba Demir
All Theses
Estimating the concentration of gases including carbon monoxide (CO) in the hydrogen fuel exiting the reformer and entering the fuel cell is imperative. A high concentration of CO can cause fuel-cell catalyst poisoning, which permanently destroys the cell. Current practices call for utilizing expensive and bulky spectral analyzers to achieve this task. In addition to their high cost, these methodologies, undoubtedly, hinder the portability and self-containment of the cell. To overcome these problems and achieve the desired objectives of a portable, self-contained, and real-time measurement module, this thesis presents and experimentally investigates a new enabling technology based on utilizing an …
Vibration Analysis Of Piezoelectric Microcantilever Sensors, Amin Salehi-Khojin
Vibration Analysis Of Piezoelectric Microcantilever Sensors, Amin Salehi-Khojin
All Dissertations
The main objective of this dissertation is to comprehensively analyze vibration characteristics of microcantilever-based sensors with application to ultra small mass detection and low dimensional materials characterization. The first part of this work focuses on theoretical developments and experimental verification of piezoelectric microcantilevers, commercially named Active Probes, which are extensively used in most today's advanced Atomic Force Microscopy (AFM) systems. Due to special geometry and configuration of Active Probes, especially multiple jump discontinuities in their cross-section, a general and comprehensive framework is introduced for forced vibration and modal analysis of discontinuous flexible beams. More specifically, a general formulation is obtained …
On New Applications And Sensitivity Enhancement Of Cantilever-Based Sensing Systems, Calvin Bradley
On New Applications And Sensitivity Enhancement Of Cantilever-Based Sensing Systems, Calvin Bradley
All Theses
Cantilever-based Sensing Systems (CSS) have become a focal area for research with the rise of micro- and nanotechnology. History has led us to use cantilever beams as one of the foremost sensing devices for small scale applications, beginning with the atomic force microscopy, and then being expanded into numerous sensor devices. The CSS include such applications as accelerometers, thermal and chemical sensors which are expanding into the applications of mass sensing and material characterization. Soon, this technology may be used in 'lab on chip' biosensing applications.
This study covers the experimentation into new CSS applications and sensitivity enhancement. In order …
Nonlinear Modeling Of The Adsorption-Induced Surface Stress In Piezoelectrically-Driven Microcantilever Biosensors, Mana Afshari
Nonlinear Modeling Of The Adsorption-Induced Surface Stress In Piezoelectrically-Driven Microcantilever Biosensors, Mana Afshari
All Theses
Microcantilever-based biosensors are rapidly becoming an enabling sensing technology for a variety of label-free biological applications due to their extreme applicability, versatility and low cost. These sensors operate through the adsorption of species on the functionalized surface of microcantilevers. The adsorption of biological species induces surface stress which originates from the molecular interactions such as adhesion forces of attraction/repulsion, electrostatic forces or the surface charge redistribution of the underlying substrate. This surface stress, consequently, alters the resonance frequency of the microcantilever beam.
This study presents a general framework towards modeling resonance frequency changes induced due to the surface stress arising …
Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi
Nonlinear Vibration And Frequency Response Analysis Of Nanomechanical Cantilever Beams, Seyed Nima Mahmoodi
All Dissertations
Microcantilevers are one the most commonly utilized microelectromechanical systems in a variant of the ultra-precise scanning and characterization application. Of particular interest, the problem of vibrations of microcantilevers has recently received considerable attention due to its application in several nanotechnological instruments such as atomic force microscopy, nanomechanical cantilever sensors and friction force microscopy. For applications such as these, the problem of coupled flexural-torsional nonlinear vibrations of a piezoelectrically-actuated microcantilever beam is considered in this dissertation. The actuation and sensing are both facilitated through bonding a piezoelectric layer (here, ZnO) on the microcantilever surface. The beam is considered to have simultaneous …