A nonlinear identification scheme is provided for a LTI-system with a feedback-nonlinearity, which depends on the input and LTI-system output. This is especially the case for MEMS, where the electrostatic field depends on the displacement and input voltage. The fact, that the algorithm only requires a matrix inversion and singular value decomposition, makes it possible to use the identification scheme for online-estimation. There is also no other a-priori knowledge about the system, except the order, needed.

Die Arbeit beschreibt die Entwicklung und Evaluierung einer Technologieplattform für die Herstellung von oberflächennahen Mikrostrukturen mit hohen Aspektverhältnissen. Grundlage dieser Technologieplattform stellt ein neuartiges Konzept zur mechanischen und elektrischen Kontaktierung beweglicher Elemente mittels spezieller Träger dar, deren typische Breite unterhalb eines Mikrometers liegt. Basierend hierauf werden drei unterschiedliche Prozessabläufe zur Herstellung der Mikrostrukturen, auch als Air gap Insulated Microstructures (AIM) bezeichnet, vorgestellt. Der Schwerpunkt dieser Arbeit liegt dabei auf der mehrschichtigen Trägervariante mit Isolationsebene und Leitungsebene. Verschiedene Schichtkombinationen, bestehend aus Siliziumnitrid, Siliziumdioxid und Aluminium, sind in ihrem mechanischen, thermischen und Langzeitverhalten charakterisiert und im Hinblick auf ihre Anwendbarkeit für die Träger bewertet. Für die Strukturierung der Siliziumelemente wird ein Verfahren basierend auf einem CF-Polymer als Passivierungsschicht beschrieben. Neben verschiedenen Ausfallmechanismen für die Passivierung werden gezielte Optimierungen der Abscheide- und Ätzprozesse erläutert sowie deren Resultate dargestellt. Für die vollständige Trennung von Substrat und seismischer Masse ist eine isotrope, vom Aspektverhältnis nahezu unabhängige Siliziumstrukturierung nötig. Entsprechende Betrachtungen und Untersuchungen hierzu, unter Verwendung der Reaktionsgase SF6 und O2, stellen den Abschluss der Untersuchungen zur Prozessentwicklung dar. Um die Leistungsfähigkeit der Technologieplattform zu demonstrieren, erfolgt die Herstellung verschiedener Sensoren und Aktoren. Die Charakterisierung dieser Elemente in ihrem mechanischen, thermischen und Langzeitverhalten stellt den Abschluss dieser Arbeit dar.

Diese Diplomarbeit beschäftigt sich mit der Entwicklung von Teststrukturen zur Charakterisierung von Mikrosystemen auf Waferebene. Sie dienen zur Bestimmung von Prozesstoleranzen. Ziel dieser Arbeit ist es, einen Algorithmus zu entwickeln, mit dem Teststrukturen optimiert werden können. Dazu wird ein Ansatz zur Optimierung von Teststrukturen mittels eines Genetischen Algorithmus untersucht. Grundlage für diesen ist eine Bewertung der Strukturen hinsichtlich der Sensitivität gegenüber den Fertigungsparametern und der Messbarkeit der Eigenmoden. Dem Leser wird zuerst ein Einblick in das Themengebiet und in die Verwendung von Teststrukturen gegeben. Es folgen Grundlagen zur Fertigung und Messung von Mikrosystemen, zur Parameteridentifikation, sowie zu Optimierungsalgorithmen. Anschließend wird ein Bewertungs- und Optimierungskonzept, sowie eine Softwareimplementation für die sich aus der Optmierung ergebenden Aufgaben, vorgestellt. Unter anderem eine Eigenmodenerkennung mittels Neuronalem Netz und einer auf der Vandermond’schen Matrix basierende Datenregression. Die Ergebnisse aus der Umsetzung durch ein Testframework werden abschließend erläutert. Es wird gezeigt, dass die Optimierung von Teststrukturen mittels Genetischem Algorithmus möglich ist. Die dargestellte Bewertung liefert für die untersuchten Teststrukturen nachvollziehbare Resultate. Sie ist in der vorliegenden Form allerdings auf Grund zu grober Differenzierung nicht für den Genetischen Algorithmus geeignet. Entsprechende Verbesserungsmöglichkeiten werden gegeben. / This diploma thesis deals with the development of test-structures for the characterization of microsystems on wafer level. Test-structures are used for the determination of geometrical parameters and material properties deviations which are influenced by microsystem fabrication prozesses. The aim of this work is to establish principles for the optimization of the test-structures. A genetic algorithm as an approach for optimization is investigated in detail. The reader will get an insight in the topic and the application of test-structures. Fundamentals of fabrication and measurement methods of microsystems, the parameter identification procedure and algorithms for optimization follow. The procedures and a corresponding software implementation of some applied issues, which are needed for the optimization of test structures, are presented. Among them are neural network algorithms for mode identification and a data regression algorithm, based on Vandermonde Matrix. Results of implemented software algorithms and an outlook conclude this work. It is shown, that the optimization of test-structure using a genetic algorithm is possible. An automated parameter variation procedure and the extraction of important test-structures parameters like sensitivity and mode order are working properly. However, the presented evaluation is not suitable for the genetic algorithm in the presented form. Hence, improvements of evaluation procedure are suggested.

Zugl.: Freiburg (Breisgau), Univ., Diss., 2009

Zugl.: Saarbrücken, Univ., Diss., 2009

Fossil fuels and their byproducts are a vital part of our economy, and society. Until renewable energy sources and energy storage technologies advance to the point where they are reliable and inexpensive, the US Economy will continue to depend upon fossil fuels. Current resources are being consumed, and the "easy to reach" reserves are becoming depleted. This leads to the requirement for more exploratory drilling, and the potential for more disasters like the recent Deepwater Horizon spill in the Gulf of Mexico. Drilling is the first of several steps in the creation of a productive oil or natural gas well. Completing a well involves casing the walls in concrete to prevent damage to the surrounding rock formations and to ensure that all of the oil or gas is captured without escaping to the surrounding environment. Ensuring the piping, which is used to case wells, is assembled correctly and to manufacturer's specifications is the focus of this study. Individual pipe sections are screwed together with a requirement for torque and number of turns. Each joint must be verified to ensure integrity, and minimize the possibility of a spill or leak. The torque measurement can be accomplished by a "torque sub", a sensor installed in-line with the drill string. The torque sub is a wireless sensor that transmits torque data to the control system for logging and display. This thesis defines the parameters required to integrate a "number of turns" measurement into an existing torque sub so that both parameters can be captured, recorded and reported using a single device. The Yost Engineering 3-Space Sensor was evaluated for use in this application. The configuration that gave the most accurate data was selected, along with the determination of some correction factors to account for site specific variation in the signals. A calibration algorithm is discussed, along with several unique methods for ensuring that the sensor output doesn't drift over the course of the joint make-up process. / text

This thesis describes novel microel ectromechanical system (MEMS) based electrochemical gas sensors and methods of fabrication. This thesis presents the research in two parts. In the first part, a method to handle a thin silicon wafer using an electrochemically active adhesive is described. Handling of a thin silicon wafer is an important issue in 3D-IC manufacturing where through silicon vias (TSVs) is an enabling technology. Thin silicon wafers are flexible and fragile, therefore difficult to handle. In addressing the need for a reliable solution, a method based on an electrochemically active adhesive was developed. In this method, an electrochemically active adhesive was diluted and spin coated on a 100 mm diameter silicon wafer (carrier wafer) on which another silicon wafer (device wafer) was bonded. Device wafer was subjected to post processing fabrication technique such as wafer thinning. Successful debonding of the device wafer was achieved by applying a voltage between the two wafers. In another part of the research, a fabrication process for developing a functional nanoporous material using atomic layer deposition is presented. In order to realize a nanoporous electrode, a nanoporous anodized aluminum oxide (AAO) substrate was used, which was functionalized with very thin layers (~ 10 nm) of platinum (Pt) and aluminum oxide (Al2O3) using atomic layer deposition. Nanoporous material when used as an electrode delivers high sensitivity due to the inherent high surface area and is potentially applicable in fuel cells and in electrochemical sensing. The second part of the thesis addresses the need for a high performance gas sensor that is applicable for asthma monitoring. Asthma is a disease related to the inflammation in the airways of the lungs and is characterized by the presence of nitric oxide gas in the exhaled breath. The gas concentration of above approximately 50 parts-per-billion indicates a likely presence of asthma. A MEMS based electrochemical gas sensor was successfully designed and developed to meet the stringent requirements needed for asthma detection. Furthermore, to enable a hand held asthma measuring instrument, a miniaturized sensor with integrated electrodes and liquid electrolyte was developed. The electrodes were assembled at a wafer-level to demonstrate the feasibility towards a high volume fabrication of the gas sensors. In addition, the designed amperometric gas sensor was successfully tested for hydrogen sulphide concentration, which is a bio marker for bad breath. / <p>QC 20150907</p>

Biological research over the past several decades has elucidated some of the mechanisms behind highly mobile, efficient, and robust locomotion in insects such as the cockroach. Roboticists have used this information to create biologically-inspired machines capable of running, jumping, and climbing robustly over a variety of terrains. To date, little work has been done to develop an at-scale insect-inspired robot capable of similar feats, due to limitations in fabrication, actuation, and electronics integration at small scales. This thesis addresses these challenges, focusing on the mechanical design and fabrication of a sub-2g walking robot, the Harvard Ambulatory MicroRobot (HAMR). The development of HAMR includes modeling and parameter selection for a two degree of freedom leg powertrain that enables locomotion. In addition, a design inspired by pop-up books that enables fast and repeatable assembly of the miniature walking robot is presented. Finally, a method to drive HAMR resulting in speeds up to 37cm/s is presented, along with simple control schemes. / Engineering and Applied Sciences

The coupling of macroscopic objects via the optical near-field can generate strong attractive and repulsive forces. Here, I explore the static and dynamic optomechanical interactions that take place in a geometry consisting of a silicon nanomembrane patterned with a square-lattice photonic crystal suspended above a silicon-on-insulator substrate. This geometry supports a hybridized optical mode formed by the coupling of eigenmodes of the membrane and the silicon substrate layer. This system is capable of generating nanometer-scale deflections at low optical powers for membrane-substrate gaps of less than 200 nm due to the presence of an optical cavity created by the photonic crystal that enhances both the optical force and a force that arises from photo-thermal-mechanical properties of the system. Feedback between Brownian motion of the membrane and the optical and photo-thermal forces lead to dynamic interactions that perturb the mechanical frequency and linewidth in a process known as ``back-action.'' The static and dynamic properties of this system are responsible for optical bistability, mechanical cooling and regenerative oscillations under different initial conditions. Furthermore, solid objects separated by a small distance experience the Casimir force, which results from quantum fluctuations of the electromagnetic field (i.e. virtual photons).The Casimir force supplies a strong nonlinear perturbation to membrane motion when the membrane-substrate separation is less than 150 nm. Taken together, the unique properties of this system makes it an intriguing candidate for transduction, accelerometry, and sensing applications. / Engineering and Applied Sciences

On-chip characterization devices have been used to extract the Young’s modulus, average stress and stress gradient of polysilicon doped with phosphorus using thermal diffusion. Devices for extracting the Young’s modulus, average stress and stress gradients have been designed to work within the range of expected material property values. A customized fabrication process was developed and the devices were fabricated. Static and resonant tests were performed using clamped-clamped and cantilever beams in order to extract material properties. The experimental setup and detailed experimental results and analysis are outlined within. Several doping concentrations have been studied and it has been concluded that the Young’s modulus of polysilicon doped for 2 hours increases by approximately 50GPa and the average stress of polysilicon doped for 2.5 hours becomes more tensile by approximately 63 MPa. It has also been found that short doping times can introduce a large enough stress gradient to create a concave up curvature in free-standing structures. This work was performed in order to determine the usability of doping as a means to increase the sensitivity of temperature and pressure sensors for harsh environments. It has been concluded that doping is a promising technique and is worth studying further for this purpose.