Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

PDF

Theses/Dissertations

Sensor

Discipline
Institution
Publication Year
Publication

Articles 121 - 129 of 129

Full-Text Articles in Engineering

A Compliant Threshold Acceleration Sensor Integrated With Radio Frequency Identifiable Tags, Benjamin L. Todd Jul 2008

A Compliant Threshold Acceleration Sensor Integrated With Radio Frequency Identifiable Tags, Benjamin L. Todd

Theses and Dissertations

Fully compliant bistable mechanisms have been proposed to be used as threshold accelerometers. The advantages to using these devices are that they require no external power to operate and maintain their sensing state. Using this characteristic the devices can be integrated with passive radio frequency identification tags (RFID). This allows for the sensing package to lay dormant with no maintenance needed until the sensor is read by the RFID reader. This thesis presents a successfully fabricated and integrated threshold accelerometer with a passive RFID tag. This in turn has been successfully read with an RFID reader and shown to act …

Go to article

Vibration Analysis Of Piezoelectric Microcantilever Sensors, Amin Salehi-Khojin May 2008

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 …

Go to article

Incorporation Of Polydiacetylene Sensors Into Commercial Polymers, Jennifer Kauffman May 2008

Incorporation Of Polydiacetylene Sensors Into Commercial Polymers, Jennifer Kauffman

All Dissertations

Polydiacetylenes (PDAs) exhibit a chromatic response to solvents, temperature, strain and other environmental perturbations. When formed in a solid-state polymerization, the backbone of the polymer is planar and continuous π-overlap is observed. However, when the PDA backbone is distorted by an outside force the extended conjugation is interrupted and an optical shift from blue to red occurs. By exploiting the PDAs properties within polymer systems, smart fibers and films have been created that enhance the original intention of the host. Under this umbrella, a strain sensitive polydiacetylene-polyurethane blend was created using 3 and 4-butoxycarbonylmethylurethane PDA and a medical grade polyurethane, …

Go to article

Design Of Piezoresistive Mems Force And Displacement Sensors, Tyler Lane Waterfall Sep 2006

Design Of Piezoresistive Mems Force And Displacement Sensors, Tyler Lane Waterfall

Theses and Dissertations

MEMS (MicroElectroMechanical Systems) sensors are used in acceleration, flow, pressure and force sensing applications on the micro and macro levels. Much research has focused on improving sensor precision, range, reliability, and ease of manufacture and operation. One exciting possibility for improving the capability of micro sensors lies in exploiting the piezoresistive properties of silicon, the material of choice in many MEMS fabrication processes. Piezoresistivity—the change of electrical resistance due to an applied strain—is a valuable material property of silicon due to its potential for high signal output and on-chip and feedback-control possibilities. However, successful design of piezoresistive micro sensors requires …

Go to article

Solid-State Impact-Ionization Multiplier, Hong-Wei Lee Mar 2006

Solid-State Impact-Ionization Multiplier, Hong-Wei Lee

Theses and Dissertations

This dissertation presents an innovative solid-state current amplifier based on impact-ionization. Unlike avalanche photodetectors which use the same amplification principle, this device can be integrated with any external current source. A discrete amplifier was built on a silicon surface using standard CMOS fabrication processes including lithography, oxidation, ion implantation, diffusion, chemical wet etching, metal deposition, annealing, and rapid thermal processing. Testing was performed by connecting the device to a silicon photodiode, indium-gallium-arsenide photodiodes, and a function generator to demonstrate its compatibility with arbitrary current sources. Current gains above 100 along with pre-amplified leakage currents of less than 10 nA were …

Go to article

A Framework For An Implantable Wireless Pressure And Volume Sensor Focusing On The Diagnosis And Treatment Of Shunt Failure In Hydrocephalus Patients, Donald Monte Wichern Jan 2006

A Framework For An Implantable Wireless Pressure And Volume Sensor Focusing On The Diagnosis And Treatment Of Shunt Failure In Hydrocephalus Patients, Donald Monte Wichern

Theses and Dissertations

The framework for a permanently implantable wireless compliance sensor was developed and validated using laboratory experiments. The proposed sensor would measure the intracranial pressure and fluid volume in the brain and return this information to a monitoring device. The designed sensor received power remotely from the monitoring device negating the need for an implanted power source. Impedance measurement estimation techniques were suggested, studied and applied to the compliance sensing system. A new impedance measurement technique, accounting for multiple variability in the domain, was developed. An extensive simulation environment was designed and used to develop the laboratory experiments and hardware. The …

Go to article

Novel Conceptual Design And Anlysis Of Polymer Derived Ceramic Mems Sensors For Gas Turbine Environment, Narasimha Nagaiah Jan 2006

Novel Conceptual Design And Anlysis Of Polymer Derived Ceramic Mems Sensors For Gas Turbine Environment, Narasimha Nagaiah

Electronic Theses and Dissertations

Technical challenges for developing micro sensors for Ultra High Temperature and turbine applications lie in that the sensors have to survive extremely harsh working conditions that exist when converting fuel to energy. These conditions include high temperatures (500-1500°C), elevated pressures (200-400 psi), pressure oscillations, corrosive environments (oxidizing conditions, gaseous alkali, and water vapors), surface coating or fouling, and high particulate loading. Several technologies are currently underdeveloped for measuring these parameters in turbine engines. One of them is an optical-based non-contact technology. However, these nondirective measuring technologies lack the necessary accuracy, at least at present state. An alternative way to measure …

Go to article

Intrusion Detection In Wireless Sensor Networks, Hong Nhung Nguyen Jan 2006

Intrusion Detection In Wireless Sensor Networks, Hong Nhung Nguyen

Electronic Theses and Dissertations

There are several applications that use sensor motes and researchers continue to explore additional applications. For this particular application of detecting the movement of humans through the sensor field, a set of Berkley mica2 motes on TinyOS operating system is used. Different sensors such as pressure, light, and so on can be used to identify the presence of an intruder in the field. In our case, the light sensor is chosen for the detection. When an intruder crosses the monitored environment, the system detects the changes of the light values, and any significant change meaning that a change greater than …

Go to article

Polarimetric Temperature Sensor Using Core-Replaced Fiber, Benjamin L. Ipson Nov 2004

Polarimetric Temperature Sensor Using Core-Replaced Fiber, Benjamin L. Ipson

Theses and Dissertations

Optical fibers are increasingly being used to create sensing devices. The D-fiber has an elliptical core and exhibits birefringence. This birefringence can be used to create a polarimetric sensor. The elliptical core supports two orthogonal modes that have separate effective indices of refraction. The indices of refraction change with a change in temperature. Since the effective indices of refraction change differently for the two modes, the birefringence also changes. This change in birefringence can be seen as a change in detected power through the fiber through the use of polarizers. The fiber then becomes a temperature sensor. The sensitivity of …

Go to article

First Prev