This thesis presents the theoretical analysis and experiment results of MEMS sensors designed for the application of low frequency vibration sensing. Each sensor consists of a proof mass connected to a folded beam micro-flexure, with an attached capacitive comb drive for displacement sensing. Three comb drive arrangements are evaluated, the transverse, lateral, and tri-plate differential. The sensors are fabricated using the well developed foundry processes of PolyMUMPS and SoiMUMPS. In addition, a capacitance to voltage readout circuit is fabricated using discrete components. Static tests, evaluating the capacitance to displacement relation, are conducted on a six degree of freedom robotic manipulator, and dynamic tests evaluating the sensor response to sinusoidal excitations are conducted on a vibrating beam. The end use of the sensor involves real-time vibration monitoring of automobile mechanical systems, such as power seats, windshield wipers, mirrors, trunks, and windows, allowing for early detection of mechanical faults before catastrophic failure.

This thesis presents the theoretical analysis and experiment results of MEMS sensors designed for the application of low frequency vibration sensing. Each sensor consists of a proof mass connected to a folded beam micro-flexure, with an attached capacitive comb drive for displacement sensing. Three comb drive arrangements are evaluated, the transverse, lateral, and tri-plate differential. The sensors are fabricated using the well developed foundry processes of PolyMUMPS and SoiMUMPS. In addition, a capacitance to voltage readout circuit is fabricated using discrete components. Static tests, evaluating the capacitance to displacement relation, are conducted on a six degree of freedom robotic manipulator, and dynamic tests evaluating the sensor response to sinusoidal excitations are conducted on a vibrating beam. The end use of the sensor involves real-time vibration monitoring of automobile mechanical systems, such as power seats, windshield wipers, mirrors, trunks, and windows, allowing for early detection of mechanical faults before catastrophic failure.

Online Oil Debris Monitors (ODM) provide a direct, effective and reliable approach to machinery condition monitoring. ODM can be used to monitor the condition of complex machines, such as airplane engines, electric generators, wind turbines, or other machines with oil circulation systems. The principle of the sensor is to detect the quantity and the size of metal particles in the flowing oil. The current available ODM sensors suffer from sensitivity to vibrations, as their electromagnetic response is largely affected by interfering vibrations. This thesis presents a novel structure and algorithms to separate and eliminate the vibration interference. In the new structure, a dual channel system is designed as opposed to previous single channel systems. Three signal processing algorithms have been developed and tested using experimental data from a prototype. They have shown to be effective, as detailed in the thesis.

Online Oil Debris Monitors (ODM) provide a direct, effective and reliable approach to machinery condition monitoring. ODM can be used to monitor the condition of complex machines, such as airplane engines, electric generators, wind turbines, or other machines with oil circulation systems. The principle of the sensor is to detect the quantity and the size of metal particles in the flowing oil. The current available ODM sensors suffer from sensitivity to vibrations, as their electromagnetic response is largely affected by interfering vibrations. This thesis presents a novel structure and algorithms to separate and eliminate the vibration interference. In the new structure, a dual channel system is designed as opposed to previous single channel systems. Three signal processing algorithms have been developed and tested using experimental data from a prototype. They have shown to be effective, as detailed in the thesis.

The reflection wavelength of Fiber Bragg Grating is sensitive to the strain and the temperature¡¦s variation. We use Fiber Bragg Grating to be the sensor head and measure the vibration frequency in constant temperature environment. The vibration of object can make the sinusoidal strain to Fiber Bragg Grating, and it will make a little phase difference to the light of the fiber. Using the interferometer and demodulation system, we can measure the phase difference and vibration frequency. Our sensor configuration is made up of imbalance Mach-Zehnder interferometer and Fiber Bragg Grating. The two light of different path need different time to pass through the vibration source, so they make phase difference. We use the demodulation circuit to measure the phase difference causing by vibration and get the vibration frequency. Our experiment structure is a novel configuration of Fiber Bragg Grating vibration sensor. Its intensity of signal is larger than the intensity of original sensor configuration, about 4dB.The novel sensor configuration is easier spread than traditional accelerometer and it is designed of all fiber. The accuracy for measuring low frequency vibration is 99.971%. The Dynamic range of the system is more than 45dB. It is larger than the dynamic range of original sensor configuration, about 9dB. The smallest signal that can be measured is about 0.0075rad.

Online Oil Debris Monitors (ODM) provide a direct, effective and reliable approach to machinery condition monitoring. ODM can be used to monitor the condition of complex machines, such as airplane engines, electric generators, wind turbines, or other machines with oil circulation systems. The principle of the sensor is to detect the quantity and the size of metal particles in the flowing oil. The current available ODM sensors suffer from sensitivity to vibrations, as their electromagnetic response is largely affected by interfering vibrations. This thesis presents a novel structure and algorithms to separate and eliminate the vibration interference. In the new structure, a dual channel system is designed as opposed to previous single channel systems. Three signal processing algorithms have been developed and tested using experimental data from a prototype. They have shown to be effective, as detailed in the thesis.

Online Oil Debris Monitors (ODM) provide a direct, effective and reliable approach to machinery condition monitoring. ODM can be used to monitor the condition of complex machines, such as airplane engines, electric generators, wind turbines, or other machines with oil circulation systems. The principle of the sensor is to detect the quantity and the size of metal particles in the flowing oil. The current available ODM sensors suffer from sensitivity to vibrations, as their electromagnetic response is largely affected by interfering vibrations. This thesis presents a novel structure and algorithms to separate and eliminate the vibration interference. In the new structure, a dual channel system is designed as opposed to previous single channel systems. Three signal processing algorithms have been developed and tested using experimental data from a prototype. They have shown to be effective, as detailed in the thesis.

Basic resonator structures for frequency-selective capacitive vibration sensors which exploit their mechanical resonance peak for spectral selectivity are developed and analyzed. As an important capability, the stuctures offer voltage-controlled frequency tuning realized by electrostatic principles. Direct electrostatic tuning based on displacement-dependent electrostatic forces as well as tuning by stress-stiffening based on constant electrostatic forces are discussed. The sensor structures are designed for fabrication using common silicon surface microtechnologies. Experimental tests of both mentioned tuning principles are carried out at structures fabricated using a surface technology known as SCREAM. A considerable part of the work focusses on nonlinear oscillations of the mechanical resonator at large amplitudes arising in resonance. Dimensioning rules for minimum nonlinear disturbance are derived from a detailed analysis of the Duffing oscillator. Various capacitive principles for signal detection and electrostatic frequency tuning are evaluated in terms of nonlinearity. A novel type of specially shaped electrode systems offering linear properties within an amplitude range of 10 micrometers, so-called curved comb capacitors, is developed for fabrication in SCREAM technology. / In der vorliegenden Arbeit werden Grundstrukturen frequenzselektiver kapazitiver Vibrationssensoren entwickelt und analysiert, deren spektrale Selektionswirkung durch Ausnutzung ihrer mechanischen Resonanzüberhöhung entsteht. Wesentliches Merkmal der Strukturen ist ihre spannungsgesteuerte Abstimmbarkeit, die auf elektrostatischen Prinzipien beruht. Es werden die direkte elektrostatische Frequenzabstimmung, basierend auf positionsabhängigen Feldkräften, sowie das Prinzip des Stress-Stiffening, basierend auf einer konstanten elektrostatischen Kraft, diskutiert. Die Entwicklung konzentriert sich auf Sensorstrukturen, die in klassischen Oberflächentechnologien gefertigt werden können. Experimentelle Tests der beiden genannten Abstimmprinzipien werden anhand von Strukturen in oberflächennaher Silizium-bulk-Mikromechanik (SCREAM) durchgeführt. Schwerpunkt der Arbeit sind nichtlineare Schwingungen der mechanischen Resonatorkomponente bei großen Amplituden, die durch die Resonanzüberhöhung entstehen. Für den Sonderfall des Duffing-Schwingers werden Dimensionierungsregeln zur Minimierung der Nichtlinearitäten entwickelt. Kapazitive Prinzipien zur Detektion bzw. elektrostatischen Abstimmung werden hinsichtlich ihrer Linearität geprüft. Es werden neuartige Elektrodensysteme für die SCREAM-Technologie, sogenannte Kurvenkammsysteme entwickelt, die bei Schwingamplituden bis zu 10 Mikrometer linear arbeiten.

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First two chapters of this paper deals with the division of optical fiber sensors, digital signal processing and includes price comparison of four experimental sensors. In chapter three analysis, description and evaluation of measurment has been demonstrated on Mach - Zehnder interferometer. Last chapter is about application for signal analysis from vibration sensors. Description contains snippets from source code and graphical user interface. This paper includes three fields - fiber optics, digital signal processing and creation of application - and thanks to them it provides solid basis for study of optic fiber sensors.