This thesis reports the design and modelling of a MEMS (Micro Electro Mechanical system) based inertial accelerometer. The main motivation to design a differential type of accelerometer is that such a kind of structure allows differential electrostatic actuation and capacitive sensing. They can be operated at the border of stability also so that the “pull in” operation mode can be explored. Such kinds of structures have a wide range of applications because of their high sensitivity. One is in the field of minimally invasive surgery where accelerometers will be combined with gyroscopes to be used in the navigation of surgical tools as a inertial micro unit (IMU). The choice for the design of a structure with 1 Degree ofFreedom(DOF) , instead of a 2-DOF device was instigated by the simplicity of the design and by a more efficient 1-DOF dynamic model. The accelerometers were designed and optimized using the MATLAB simulator and COVENTORWARE simulation tool. First set of devices is fabricated using a commercial foundry process called SOIMUMPs. The simulation tests show that the SOl accelerometer system yields 8.8kHz resonant frequency, with a quality factor of 10 and 2.l2mV/g sensitivity. To characterize the accelerometer a new semi automatic tool was formulated for the noise analysis and noise based optimization of the accelerometer design and the analysis estimation shows that there is a trade off between the SIN ratio and the sensitivity and for the given design could be made much better in terms of SIN by tuning its resonant frequency.

This thesis reports the design and modelling of a MEMS (Micro Electro Mechanical system) based inertial accelerometer. The main motivation to design a differential type of accelerometer is that such a kind of structure allows differential electrostatic actuation and capacitive sensing. They can be operated at the border of stability also so that the “pull in” operation mode can be explored. Such kinds of structures have a wide range of applications because of their high sensitivity. One is in the field of minimally invasive surgery where accelerometers will be combined with gyroscopes to be used in the navigation of surgical tools as a inertial micro unit (IMU). The choice for the design of a structure with 1 Degree ofFreedom(DOF) , instead of a 2-DOF device was instigated by the simplicity of the design and by a more efficient 1-DOF dynamic model. The accelerometers were designed and optimized using the MATLAB simulator and COVENTORWARE simulation tool. First set of devices is fabricated using a commercial foundry process called SOIMUMPs. The simulation tests show that the SOl accelerometer system yields 8.8kHz resonant frequency, with a quality factor of 10 and 2.l2mV/g sensitivity. To characterize the accelerometer a new semi automatic tool was formulated for the noise analysis and noise based optimization of the accelerometer design and the analysis estimation shows that there is a trade off between the SIN ratio and the sensitivity and for the given design could be made much better in terms of SIN by tuning its resonant frequency.

Purpose-To examine physical activity levels after THA and relate it to pain, disability, sleep, and body composition. Methods-Cross-sectional, observational study of THA patients 1-3 years post-surgery (n=17, male). 7 day accelerometry (2 second epoch, GT3X) derived step and energy related physical activity. Body composition (WC, BMI) and pain (VAS) were measured. Disability and sleep were measured using the HOOS, Oxford Hip Score, and PSQI. Results-Participants averaged 9143 (398.2) steps/day. Statistical analysis failed to show a significant difference in comparison to the age-matched normative population. Time in moderate-vigorous intensity PA was 55.8 (22.5) minutes/day; higher than the value for the age-matched normatives. VAS function was significantly correlated to step rate (r=0.483, p<0.05). Step rate was related to Oxford Hip (r=0.486, p<0.05). VAS function was found to account for 80.7% of the variance in the HOOS and 78% of the variance in the Oxford Hip Score but no PA measures were returned. Conclusion-Activity levels in the male THA population lacking co-morbidities are clinically at par with age-matched peers and near minimum activity guidelines. Traditional PA measures were unrelated to disability measures.

Purpose-To examine physical activity levels after THA and relate it to pain, disability, sleep, and body composition. Methods-Cross-sectional, observational study of THA patients 1-3 years post-surgery (n=17, male). 7 day accelerometry (2 second epoch, GT3X) derived step and energy related physical activity. Body composition (WC, BMI) and pain (VAS) were measured. Disability and sleep were measured using the HOOS, Oxford Hip Score, and PSQI. Results-Participants averaged 9143 (398.2) steps/day. Statistical analysis failed to show a significant difference in comparison to the age-matched normative population. Time in moderate-vigorous intensity PA was 55.8 (22.5) minutes/day; higher than the value for the age-matched normatives. VAS function was significantly correlated to step rate (r=0.483, p<0.05). Step rate was related to Oxford Hip (r=0.486, p<0.05). VAS function was found to account for 80.7% of the variance in the HOOS and 78% of the variance in the Oxford Hip Score but no PA measures were returned. Conclusion-Activity levels in the male THA population lacking co-morbidities are clinically at par with age-matched peers and near minimum activity guidelines. Traditional PA measures were unrelated to disability measures.

This thesis reports the design and modelling of a MEMS (Micro Electro Mechanical system) based inertial accelerometer. The main motivation to design a differential type of accelerometer is that such a kind of structure allows differential electrostatic actuation and capacitive sensing. They can be operated at the border of stability also so that the “pull in” operation mode can be explored. Such kinds of structures have a wide range of applications because of their high sensitivity. One is in the field of minimally invasive surgery where accelerometers will be combined with gyroscopes to be used in the navigation of surgical tools as a inertial micro unit (IMU). The choice for the design of a structure with 1 Degree ofFreedom(DOF) , instead of a 2-DOF device was instigated by the simplicity of the design and by a more efficient 1-DOF dynamic model. The accelerometers were designed and optimized using the MATLAB simulator and COVENTORWARE simulation tool. First set of devices is fabricated using a commercial foundry process called SOIMUMPs. The simulation tests show that the SOl accelerometer system yields 8.8kHz resonant frequency, with a quality factor of 10 and 2.l2mV/g sensitivity. To characterize the accelerometer a new semi automatic tool was formulated for the noise analysis and noise based optimization of the accelerometer design and the analysis estimation shows that there is a trade off between the SIN ratio and the sensitivity and for the given design could be made much better in terms of SIN by tuning its resonant frequency. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

Low frequency (<100 Hz) acceleration sensing with low noise and traceability is critical in seismology, military surveillance, and emerging technologies. Typically, MEMS (Microelectromechanical systems) are not ideally suited for low frequency accelerometry since their fundamental thermomechanical fluctuation noise limit is higher than in macroscopic accelerometers of higher proof mass. However recent work on thin film MEMS resonators shows promising development in the reduction of damping which in turn reduces fundamental thermomechanical fluctuation noise limit. We aim to harness these low damping thin films in the context of accelerometry, by mass loading them to make them sensitive to acceleration. This work reports an experimental characterization of a mass-loaded silicon nitride membrane-based resonator, which is investigated towards the development of accelerometers for acceleration sensing at low frequencies. We experimentally demonstrate a 1.1 × 10⁻⁶ kg proof mass system achieving a 17,950 mechanical quality factor for a 526 Hz natural resonance frequency, which compares favorably to other optically interrogated on-chip accelerometers [1]-[3]. The inferred acceleration noise floor of the device is currently limited by the displacement noise of the optical fiber displacement readout, yielding a noise amplitude spectral density of 1 μg/√Hz at 10 Hz. This thesis first details a literature review of various high-performance, mass-loaded MEMS accelerometers categorized by their transduction methods, followed by a comprehensive overview of our devices design and fabrication process. Followed by an overview of the performance of our devices under different mounting conditions. Finally, a custom finite difference simulation is presented to determine the limiting factor in our device's performance along with concluding remarks and potential future work.

The high-performance accelerometers with micro-gravity resolution and large dynamic range at very low frequencies are not only used in GPS-augmented inertial navigation, monitoring of aircrafts and space station, but also used in monitoring wind turbines for green energy. This dissertation presents the design and development of a mixed-signal, low-noise, and fourth-order sigma-delta interface circuit for the MEMS capacitive micro-gravity accelerometer. A fully-differential switched-capacitor (SC) amplifier architecture is developed with the low-frequency noise reduction through the integration of chopper-stabilization technique with lateral BJT at input stage. The effectiveness of different noise reduction techniques is also compared and verified. The application of fourth-order SC sigma-delta modulation concept to the inertial-grade accelerometer is to achieve the benefits of the digitization of the accelerometer output without compromising the resolution of the analog front-end. This open-loop interface provides 1-bit digital output stream and has the versatility of interfacing sensors with different sensitivities while maintaining minimum power dissipation and maximum dynamic range. The micromechanical accelerometers are fabricated in thick silicon-on-insulator (SOI) substrates. The accelerometer operates in air and is designed for non-peaking response with a bandwidth of 500 Hz.

Det finns i dagsläget gott om spelplattformar med stöd för accelerometer. När spel skall utvecklas mot dessa spelplattformar så är det viktig att ställa frågorna. är det lämpligt att använda accelerometern? Vilka problem innebär det? Är andra alternativ mer lämpliga? I detta arbete behandlas spelet Flygplan. Är accelerometer en lämplig kontrolltyp till flygplan eller är ett tangentbord mer lämpligt. För att få svar på frågorna utvecklades en prototyp av Flygplan med de två kontrolltyperna. Prototypen genomgick sedan tester. Resultatet visade att tangentbordskontrollen var lättare att använda än accelerometerkontrollen, skillnaden var marginell. Skillnader bestod av hur de olika kontrolltyperna användes för att styra i Flygplan, samt att spelare hade större erfarenhet av tangentbord. Fortsatt arbete med Flygplan skulle innebära att utveckla det till ett fullt spel anpassat till en mobil plattform t.ex. iPhone.

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<p>Det finns i dagsläget gott om spelplattformar med stöd för accelerometer.</p><p>När spel skall utvecklas mot dessa spelplattformar så är det viktig att ställa frågorna. är det lämpligt att använda accelerometern? Vilka problem innebär det? Är andra alternativ mer lämpliga?</p><p>I detta arbete behandlas spelet <em>Flygplan.</em> Är accelerometer en lämplig kontrolltyp till flygplan eller är ett tangentbord mer lämpligt. För att få svar på frågorna utvecklades en prototyp av <em>Flygplan </em>med de två kontrolltyperna. Prototypen genomgick sedan tester. Resultatet visade att tangentbordskontrollen var lättare att använda än accelerometerkontrollen, skillnaden var marginell. Skillnader bestod av hur de olika kontrolltyperna användes för att styra i <em>Flygplan</em>, samt att spelare hade större erfarenhet av tangentbord. Fortsatt arbete med <em>Flygplan </em>skulle innebära att utveckla det till ett fullt spel anpassat till en mobil plattform t.ex. <em>iPhone.</em></p>