This thesis presents the optimization of deep reactive ion etching process (DRIE) to achieve high precision 3-dimensional integrated micro electro mechanical systems (MEMS) sensors with high aspect ratio structures. Two optimization processes have been performed to achieve 20 &amp / #956 / m depth for 1 &amp / #956 / m opening for a dissolved wafer process (DWP) and to achieve 100 &amp / #956 / m depth for 1 &amp / #956 / m opening for silicon-on-glass (SOG) process. A number of parameters affecting the etch rate and profile angle are investigated, including the step times, etch step pressure, platen power, and electrode temperature. Silicon etch samples are prepared and processed in METU-MET facilities to understand and optimize the DRIE process parameters that can be used for the production of MEMS gyroscopes and accelerometers. The etch samples for DWP are masked using a photoresist, Shipley S1813. After the optimization process, vertical trench profiles are achieved with minimum critical dimension loss for trench depths up to 20 &amp / #956 / m. Since the selectivity of the resist is not sufficient for 100 &amp / #956 / m deep trench etch process, silicon dioxide (SiO2) is used as the mask for this process. At the end of the optimization processes, more than 100 &amp / #956 / m depth for 1 &amp / #956 / m opening with almost vertical sidewalls are achieved. In summary, this study provides an extensive understanding of the DRIE process for successful implementations of integrated MEMS sensors.

RFID has been characterized as a “disruptive technology” that has the potential to revolutionize numerous key sectors. A key advantage of passive RFID applications is the ability to wirelessly transmit automatic identification and related information using very little power. This paper presents an experimental investigation to inform the optimal configuration for programming passive ultra-high frequency (UHF) RFID media in dynamic applications. Dynamic programming solutions must be designed around the tag’s functionality, the physical programming configuration and environment. In this investigation, we present a methodology to determine an optimal configuration to maximize the systems programming efficiency for dynamic applications.

This thesis reports the development of micromachined accelerometers and gyroscopes that can be used for micromachined inertial measurement units (IMUs). Micromachined IMUs started to appear in the market in the past decade as low cost, moderate performance alternative in many inertial applications including military, industrial, medical, and consumer applications. In the framework of this thesis, a number of accelerometers and gyroscopes have been developed in three different fabrication processes, and the operation of these fabricated devices is verified with extensive tests. In addition, the fabricated accelerometers were combined with external readout electronics to obtain hybrid accelerometer systems, which were tested in industrial test facilities. The accelerometers and gyroscopes are designed and optimized using the MATLAB analytical simulator and COVENTORWARE finite element simulation tool. First set of devices is fabricated using a commercial foundry process called SOIMUMPs, while the second set of devices is fabricated using the electroplating processes developed at METU-MET facilities. The third set of devices is designed for a new advanced process based on DRIE, which is under development. Mechanical and electrical test results of the fabricated accelerometers and gyroscopes are in close agreement with the designed values. The testing of the SOI and nickel accelerometers is also performed in industrial test environments. In order to perform these tests, accelerometers are hybrid connected to commercially available capacitive readout circuits. These accelerometer systems require only two DC supply voltages for operation and provide an analog output voltage related to the input acceleration. The industrial tests show that the SOI accelerometer system yields a 799 &micro / g/&amp / #8730 / Hz average noise floor, a 1.8 mg/&amp / #8730 / Hz peak noise floor, a 22.2 mV/g sensitivity, and a 0.1 % nonlinearity, while the nickel accelerometer system yields a 228 &micro / g/&amp / #8730 / Hz average noise floor, a 375 &micro / g/&amp / #8730 / Hz peak noise floor, a 1.02 V/g sensitivity, and a 0.23 % nonlinearity. Long-term drift components of the accelerometers are determined to be smaller than 20 mg. These systems are the highest performance micromachined accelerometer systems developed in Turkey, and they can be used in implementation of a national inertial measurement unit.

Στις τελευταίες δεκαετίες η σμίκρυνση (miniaturization) έχει αποτελέσει ένα σημαντικό παράγοντα στην ανάπτυξη της τεχνολογίας. Ένας από τους κύριους στόχους της μέσω της μικρομηχανικής (micro-engineering) είναι η παραγωγή ολοκληρωμένων Μικρο-Ηλεκτρο-Μηχανικών Συστημάτων (MEMS), τα οποία χρηςιμοποιούνται σήμερα ως υποσυστήματα σε πάρα πολλές εφαρμογές. Αντικείμενο της παρούσας διατριβής είναι ο παράλληλος χειρισμός καθώς και η ανοιχτού βρόχου/άνευ αισθητήρων συναρμολόγηση μικροαντικειμένων χωρίς τη χρήση μικροβραχιόνων. Για το σκοπό αυτό η έρευνα επικεντρώθηκε σε τέσσερις διαφορετικές διαδικασίες/προσεγγίσεις: α) το μικροχειρισμό με τρισδιάστατα πεδία δυνάμεων, β) το μικροχειρισμό με προγραμματιζόμενα πεδία δυνάμεων στο επίπεδο, γ) το χειρισμό μικροαντικειμένων έγκλειστων σε σταγόνες υγρού και δ) την αυτοσυναρμολόγηση μικροαντικειμένων με ηλεκτροστατικές δυνάμεις. / In the last decades, miniaturization has become an important factor in the development of technology. One of its main objectives through the discipline of micro-engineering is the production of integrated Micro-Electro-Mechanical Systems (MEMS), which are currently used as sub-systems in many applications. The target of this thesis is the parallel manipulation and the open-loop/sensorless assembly of microparts without the use of microrobots. For this purpose, the research was focused on four different procedures: a) micromanipulation with 3D force fields, b) micromanipulation with programmable force fields on a plane, c) manipulation of microparts enclosed in a droplet of liquid and d)self-assembly of microparts with electrostatic forces.

Οι ηλεκτρομηχανικές συσκευές αποθήκευσης δεδομένων πολύ μικρής κλίμακας που βασίζονται στη χρήση ακίδων (probes) αποτελούν ανερχόμενες εναλλακτικές επιλογές για τη βελτίωση της πυκνότητας αποθήκευσης, του χρόνου πρόσβασης των δεδομένων και της απαιτούμενης ισχύος σε σχέση με τις συμβατικές συσκευές αποθήκευσης. Μία υλοποίηση μιας τέτοιας συσκευής χρησιμοποιεί θερμομηχανικές μεθόδους για την αποθήκευση πληροφορίας σε λεπτές μεμβράνες πολυμερών υλικών. Στην περίπτωση αυτή, η ψηφιακή πληροφορία αποθηκεύεται με τη μορφή κοιλωμάτων πάνω στο πολυμερές υλικό, τα οποία δημιουργούνται από τις ακίδες, διαμέτρου μερικών nm. Με στόχο την αύξηση του ρυθμού εγγραφής και ανάγνωσης χρησιμοποιούνται δισδιάστατες διατάξεις από ακίδες που λειτουργούν παράλληλα, με κάθε ακίδα να εκτελεί λειτουργίες εγγραφής /ανάγνωσης /διαγραφής σε ξεχωριστό αποθηκευτικό πεδίο. Η μετατόπιση του αποθηκευτικού μέσου σε σχέση με τη διάταξη των ακίδων επιτυγχάνεται με τη χρησιμοποίηση ηλεκτρομηχανικού συστήματος μικρής κλίμακας (MEMS). Η διάταξη MEMS αποτελείται από ένα μικρής κλίμακας σύστημα σάρωσης (microscanner) και από το τσιπ της δισδιάστατης διάταξης των ακίδων. Το σύστημα σάρωσης έχει δυνατότητα κίνησης σε δύο διευθύνσεις (x/y). Αντικείμενο της διπλωματικής εργασίας είναι η μοντελοποίηση του συστήματος σάρωσης μικρής κλίμακας. Η μοντελοποίηση του συστήματος έγινε με βάση το σύστημα του απλού αρμονικού ταλαντωτή με απόσβεση. Στα πλαίσια της εργασίας μελετάται η απόκριση του συστήματος σε διάφορους τύπους διεγέρσεων, ενώ για την προσομοίωση της συμπεριφοράς του microscanner αναπτύχθηκε εφαρμογή στην γλώσσα προγραμματισμού Visual Basic. Η εφαρμογή περιλαμβάνει γραφικό περιβάλλον με δυνατότητα ρύθμισης των παραμέτρων εξομοίωσης. / Micro-electro-mechanical-system (MEMS)-based scanning-probe storage devices are emerging as potential ultra-high-density, low-access-time, and low-power alternatives to conventional data storage. One implementation of probe-based storage uses thermomechanical means to store and retrieve information in thin polymer films. Digital information is stored by making indentations on the thin polymer film with the tips of atomic force microscope (AFM) cantilevers, which are a few nanometers in diameter. To increase the data rate, an array of probes is used, in which each probe performs read/ write/ erase operations over an individual storage field. Displacement of the storage medium relative to the array of cantilevers is achieved by using micro-electro-mechanical-system (MEMS). The MEMS assembly consists of the microscanner and the cantilever array chip. The microscanner with x and y motion range carries the storage medium. This diploma dissertation presents the modeling of the microscanner. The system models as a damped harmonic oscillator. The model response on different driven forces has been studied, whereas an application in Visual Basic has been generated to simulate the system motion. The application comprises graphic interface with simulation parameters modulation.

abstract: A Microbial fuel cell (MFC) is a bio-inspired carbon-neutral, renewable electrochemical converter to extract electricity from catabolic reaction of micro-organisms. It is a promising technology capable of directly converting the abundant biomass on the planet into electricity and potentially alleviate the emerging global warming and energy crisis. The current and power density of MFCs are low compared with conventional energy conversion techniques. Since its debut in 2002, many studies have been performed by adopting a variety of new configurations and structures to improve the power density. The reported maximum areal and volumetric power densities range from 19 mW/m2 to 1.57 W/m2 and from 6.3 W/m3 to 392 W/m3, respectively, which are still low compared with conventional energy conversion techniques. In this dissertation, the impact of scaling effect on the performance of MFCs are investigated, and it is found that by scaling down the characteristic length of MFCs, the surface area to volume ratio increases and the current and power density improves. As a result, a miniaturized MFC fabricated by Micro-Electro-Mechanical System(MEMS) technology with gold anode is presented in this dissertation, which demonstrate a high power density of 3300 W/m3. The performance of the MEMS MFC is further improved by adopting anodes with higher surface area to volume ratio, such as carbon nanotube (CNT) and graphene based anodes, and the maximum power density is further improved to a record high power density of 11220 W/m3. A novel supercapacitor by regulating the respiration of the bacteria is also presented, and a high power density of 531.2 A/m2 (1,060,000 A/m3) and 197.5 W/m2 (395,000 W/m3), respectively, are marked, which are one to two orders of magnitude higher than any previously reported microbial electrochemical techniques. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2016

abstract: Early detection and treatment of disease is paramount for improving human health and wellness. Micro-scale devices promote new opportunities for the rapid, cost-effective, and accurate identification of altered biological states indicative of disease early-onset; these devices function at a scale more sensitive to numerous biological processes. The application of Micro-Electro-Mechanical Systems (MEMS) in biomedical settings has recently emerged and flourished over course of the last two decades, requiring a deep understanding of material biocompatibility, biosensing sensitively/selectively, biological constraints for artificial tissue/organ replacement, and the regulations in place to ensure device safety. Capitalizing on the inherent physical differences between cancerous and healthy cells, our ultra-thin silicone membrane enables earlier identification of bladder cancer—with a 70% recurrence rate. Building on this breakthrough, we have devised an array to multiplex this sample-analysis in real-time as well as expanding beyond bladder cancer. The introduction of new materials—with novel properties—to augment current and create innovative medical implants requires the careful analysis of material impact on cellular toxicity, mutagenicity, reactivity, and stability. Finally, the achievement of replacing defective biological systems with implanted artificial equivalents that must function within the same biological constraints, have consistent reliability, and ultimately show the promise of improving human health as demonstrated by our hydrogel check valve. The ongoing proliferation, expanding prevalence, and persistent improvement in MEMS devices through greater sensitivity, specificity, and integration with biological processes will undoubtedly bolster medical science with novel MEMS-based diagnostics and therapeutics. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2018

Rotational falls, or somersault falls, have led to serious and fatal injuries during the cross-country phase of Eventing competitions. Research to improve the safety of the sport began in 2000 after five fatal injuries occurred in the 1999 Eventing season. These efforts led to safety devices such as air jackets, improved helmets, and frangible/deformable fences. The focus of this thesis is to develop a more complete understanding of the horse-fence interaction as the approach motion transitions to a rotational fall. To achieve this, a large distribution of inertial properties was compiled through the development of a cylinder-based inertia approximation and a citizen science effort to gather equine geometrical measurements through a survey distributed by the United States Eventing Association (USEA). Furthermore, fundamental kinematic properties of the horse and rider were gathered from the literature. These distributions were used to conduct a Monte Carlo analysis to examine if the approach conditions of the horse and rider would result in a transition to a rotational fall upon horse-fence contact. Through the analysis the sensitivity of the main control parameters was explored to determine the dominant variables in the transition.

This thesis presents the design of uBot-7, the latest version of a dexterous mobile manipulator. This platform has been iteratively developed to realize a high performance-to-cost dexterous whole body manipulator with respect to mobile manipulation. The semi-anthropomorphic design of the uBot is a demonstrated and functional research platform for developing advanced autonomous perception, manipulation, and mobility tasks. The goal of this work is to improve the uBot’s ability to sense and interact with its environment in order to increase the platforms capability to operate dexterously, through the incorporation of joint torque feedback, and safely, through the implementation of passive and active compliance. This is accomplished through incorporating series elastic actuators in its arms and torso joints, improving the mechanical design to reduce backlash, and incorporating impedance controllers in the robot. The focus of this thesis is the development of the mechanical, sensor, and controller design for the uBot-7 platform. An impedance controller is developed and evaluated on a bench top prototype series elastic actuator.

The objective for this project is to investigate various electrical and software means of control to support and advance the development of a novel vacuum adhesion system for a wall-climbing robot. The design and implementation of custom electronics and a wirelessly controlled real-time software system used to define and support the functionalities of these electronics is discussed. The testing and evaluation of the overall system performance and the performance of the several different subsystems developed, while working both individually and cooperatively within the system, is also demonstrated.