High-accuracy Motion Estimation for MEMS Devices with Capacitive Sensors

With the development of micro-electro-mechanical system (MEMS) technologies, emerging MEMS applications such as in-situ MEMS IMU calibration, medical imaging via endomicroscopy, and feedback control for nano-positioning and laser scanning impose needs for especially accurate measurements of motion using on-chip sensors. Due to their advantages of simple fabrication and integration within system level architectures, capacitive sensors are a primary choice for motion tracking in those applications. However, challenges arise as often the capacitive sensing scheme in those applications is unconventional due to the nature of the application and/or the design and fabrication restrictions imposed, and MEMS sensors are traditionally susceptible to accuracy errors, as from nonlinear sensor behavior, gain and bias drift, feedthrough disturbances, etc. Those challenges prevent traditional sensing and estimation techniques from fulfilling the accuracy requirements of the candidate applications. The goal of this dissertation is to provide a framework for such MEMS devices to achieve high-accuracy motion estimation, and specifically to focus on innovative sensing and estimation techniques that leverage unconventional capacitive sensing schemes to improve estimation accuracy. Several research studies with this specific aim have been conducted, and the methodologies, results and findings are presented in the context of three applications. The general procedure of the study includes proposing and devising the capacitive sensing scheme, deriving a sensor model based on first principles of capacitor configuration and sensing circuit, analyzing the sensor’s characteristics in simulation with tuning of key parameters, conducting experimental investigations by constructing testbeds and identifying actuation and sensing models, formulating estimation schemes is to include identified actuation dynamics and sensor models, and validating the estimation schemes and evaluating their performance against ground truth measurements. The studies show that the proposed techniques are valid and effective, as the estimation schemes adopted either fulfill the requirements imposed or improve the overall estimation performance. Highlighted results presented in this dissertation include a scale factor calibration accuracy of 286 ppm for a MEMS gyroscope (Chapter 3), an improvement of 15.1% of angular displacement estimation accuracy by adopting a threshold sensing technique for a scanning micro-mirror (Chapter 4), and a phase shift prediction error of 0.39 degree for a electrostatic micro-scanner using shared electrodes for actuation and sensing (Chapter 5).PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147568/1/davidsky_1.pd

MEMS-Based Endomicroscopes for High Resolution in vivo Imaging

Intravital microscopy is an emerging methodology for performing real time imaging in live animals. This technology is playing a greater role in the study of cellular and molecular biology because in vitro systems cannot adequately recapitulate the microenvironment of living tissues and systems. Conventional intravital microscopes use large, bulky objectives that require wide surgical exposure to image internal organs and result in terminal experiments. If these instruments can be reduced sufficiently in size, biological phenomena can be observed in a longitudinal fashion without animal sacrifice. The epithelium is a thin layer of tissue in hollow organs, and is the origin of many types of human diseases. In vivo assessment of biomarkers expressed in the epithelium in animal models can provide valuable information of disease development and drug efficacy. The overall goal of this work is to develop miniature imaging instruments capable of visualizing the epithelium in live animals with subcellular resolution. The dissertation is divided into four projects, where each contains an imaging system developed for small animal imaging. These systems are all designed using laser beam scanning technology with tiny mirrors developed with microelectromechanical systems (MEMS) technology. By using these miniature scanners, we are able to develop endomicroscopes small enough for hollow organs in small animals. The performance of these systems has been demonstrated by imaging either excised tissue or colon of live mice. The final version of the instrument can collect horizontal/oblique plane images in the mouse colon in real time (>10 frames/sec) with sub-micron resolution (<1 um), deep tissue penetration (~200 um) and large field of view (700 x 500 um). A novel side-viewing architecture with distal MEMS scanning was developed to create clear and stable image in the mouse colon. With the use of the instrument, it is convenient to pinpoint location of interest and create a map of the colon using image mosaicking. Multispectral fluorescence images can by collected at excitation wavelength ranging from 445 nm to 780 nm. The instruments have been used to 1) validate specific binding of a cancer targeting agent in the mouse colon and 2) study the tumor development in a mouse model with endogenous fluorescence protein expression. We use these studies to show that we have developed an enabling technology which will allow biologist to perform longitudinal imaging in animal models with subcellular resolution.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/136954/2/dxy_1.pd

Opto-magnonic crystals: optical manipulation of spin waves

It is well-recognized in condensed matter physics that structural and magnetic properties are intimately connected; thus controlling structure has been a successful route to controlling material properties. Extending the methodologies to high frequency modulation provides a route to controlled, bidirectional modification to material properties, expanding the range of material functionality and opening new possibilities for future developments in fields as disparate as magnetic control, spintronics, and magnonics. Ultrafast optical techniques provide one manner in which elastic and magnetic dynamics can be controlled in a material, since ultrafast pulses of light are known to excite elastic deformations while also modifying the magnetic properties of the material. Optically generated elastic waves can routinely achieve the frequency range of GHz with wavelength ranges of a few micrometers, which interestingly overlaps almost perfectly with similar wavelength spin waves. In our work, we first explored the emergence of a transient magnonic crystal after the impulsive excitation of transient grating and the phase-locked elastic wave capable of preferentially driving precessional motion in different regions of the material. Secondly we have demonstrated the first instance of elastically and parametrically driven ferromagnetic oscillator, which exhibited sum and difference frequency conversion over a wide range of frequencies. Finally, we approached magnetoelastic effects from a different point of view: the study of magnetoelastic dynamics in Ni nanowires. Connecting these experiments provide possible applications in optomagnonics research which currently utilizes artificially textured materials

Understanding and predicting transient material behaviors associated with mechanical resonance in cementitious composites

Cementitious composite materials provide a foundation for civilized life, from underlying structural bedrock to the tallest concrete structures in the world. These infrastructure materials (e.g., concrete and rock) are challenging to inspect and characterize, in part because of their heterogeneous and multi-scale compositions. Recently, nonlinear transient dynamic mechanical resonance behaviors, also known as “slow dynamic” behaviors, have been observed in damaged cementitious composite materials, yet the physical mechanisms underlying these behaviors are not understood. These phenomena hold potential to offer new insight and improved performance for monitoring the degradation of infrastructure materials. In this dissertation, I study the potential of slow dynamic behaviors for practical application as a nondestructive inspection method for infrastructure materials. The study includes experimental tests and analytical modeling. Most experiments were carried out on neat cement paste samples, which represent porous composite infrastructure materials in general. The study was divided into three components: observing the behavior at the global (macro) and micro-scales, modeling the behavior in terms of a physical or mechanistic basis, and applying the behavior to monitor degradation through a practical application. A repeatable nondestructive testing approach that uses a sequential impact device was designed to extract consistent global slow dynamic conditioning observations and characteristics from prismatic cement samples. The occurrence and existence of slow dynamic behaviors depended on the extent of damage and moisture states of a specimen. A small-scale disc vibration experiment was designed to enable imaging, using an environmental scanning electron microscope during vibration excitation in a controlled environment. Moisture migration within the paste microstructure was observed at the micron scale before and after resonance vibration of the disc. A new Mechanistic Diffusion Model (MDM) was developed to explain observed global- and micro-scale experimental results. The MDM unifies the moisture state, damage extent, and time dependence of slow dynamic behaviors. The MDM was verified through further experimentation. Finally, the slow dynamic characteristics of drying cement paste prisms with varying amounts of shrinkage reducing admixture were studied and compared to linear measurements performed on the same samples. The slow dynamic behaviors provided a measure of the bulk relative material damage at a single point in time, whereas the linear methods required measurements at two different points in time, before and after damage, in order to characterize the material. This dissertation provides a deeper understanding of slow dynamic behavior, offers a new mechanistic explanation based on moisture migration for slow dynamic behaviors in porous composite materials, and presents the basis for a single-test nondestructive approach to evaluate degradation levels in cementitious materials in a sensitive and reliable manner. The improved understanding of these dynamic behaviors will improve the design, application, and evaluation of infrastructure materials, from understanding underlying bedrock seismicity to improving structural assessments of concrete

Space-based solar power conversion and delivery systems study. Volume 2: Engineering analysis of orbital systems

Program plans, schedules, and costs are determined for a synchronous orbit-based power generation and relay system. Requirements for the satellite solar power station (SSPS) and the power relay satellite (PRS) are explored. Engineering analysis of large solar arrays, flight mechanics and control, transportation, assembly and maintenance, and microwave transmission are included

Simulation of Propagation-Distorted 2DFT Spectra of Dense Rubidium Vapor and Pump-Probe Spectroscopy of Carrier Dynamics in Colloidal Indium Arsenide Quantum Dots

Two-dimensional Fourier-transform (2DFT) spectra of the D2 line of rubidium vapor in argon buffer gas are simulated using a three-dimensional frequency domain solution of Maxwell\u27s equations that treats linear propagation distortions exactly. Simulations for the homogeneous optical Bloch model at optical densities of up to 3 are compared to measured rephasing 2DFT spectra. Experimentally observed propagation distortions are qualitatively reproduced in calculated 2DFT spectra, including peak broadening, peak splitting, and peak twisting. Varying beam overlap through the sample is crudely modeled in simulations, demonstrating that reduced beam overlap causes narrowing of the peak shape in the excitation dimension and an overall reduction in signal size. Propagation distortions, including peak splitting depth and peak twist, are found to vary with waiting time and with the excited state lifetime at a fixed total dephasing time, suggesting a coherent mechanism. A new method for reducing repetitive excitation of the sample by scanning beams with respect to a stationary sample cell using a fast steering mirror is described. This apparatus extends the average time between excitations at any point in the sample to \u3e0.3 s and accommodates a wide variety of sample cell formats, including cryostats, air-tight cuvettes, and flow cells. Colloidal indium arsenide (InAs) quantum dots (QDs) are interrogated by degenerate pump{ probe transient absorption spectroscopy at a photon energy of approximately 1.5 times the band gap using spatially-averaged excitation probabilities lower than in previously reported studies. Signatures of Auger recombination appear with a timescale of 26 +/- 5 ps. Carrier cooling and recombination pathways are explored, revealing new dynamics not observed in studies that probe the band edge

Bibliography of Lewis Research Center technical publications announced in 1988

This bibliography contains abstracts of the technical reports that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1988. Subject, author, and corporate source indexes are also included. All the publications were announced in the 1988 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Research and Technology 1990

A brief but comprehensive review is given of the technical accomplishments of the NASA Lewis Research Center during the past year. Topics covered include instrumentation and controls technology; internal fluid dynamics; aerospace materials, structures, propulsion, and electronics; space flight systems; cryogenic fluids; Space Station Freedom systems engineering, photovoltaic power module, electrical systems, and operations; and engineering and computational support

Bibliography of Lewis Research Center technical publications announced in 1980

This compilation of abstracts describes and indexes over 780 research reports, journal articles, conference presentations, patents and patent applications, and theses resulting from the scientific and engineering work performed and managed by the Lewis Research Center in 1980. All the publications were announced in Scientific and Technical Aerospace Reports and/or International Aerospace Abstracts