Kyoto University (京都大学) / 0048 / 新制・論文博士 / 博士(工学) / 乙第12493号 / 論工博第4047号 / 新制||工||1503(附属図書館) / 28243 / (主査)教授 平尾 一之, 教授 横尾 俊信, 教授 田中 勝久 / 学位規則第4条第2項該当

Vibration measurement and analysis has been an accepted method since decades to meet a number of objectives - machinery condition monitoring, dynamic qualification of any designed structural components, prediction of faults and structural aging-related problems, and several other structural dynamics studies and diagnosis. However, the requirement of the vibration measurement at number of locations in structures, machines and/or equipments makes the vibration measurement exorbitant if conventional piezoelectric accelerometers are used. Hence, there is a need for cheaper and reliable alternative for the conventional accelerometers. The Micro-Electro-Mechanical Systems (MEMS) accelerometers are one such cheap alternative. However, a significant deviation in the performance of the MEMS accelerometers has been observed in earlier research studies and also confirmed by this presented study when compared with well known conventional accelerometer. Therefore, two methods have been suggested to improve the performance of the existing MEMS accelerometers; one for correction in time domain and other in frequency domain. Both methods are based on the generation of a characteristic function (CF) for the MEMS accelerometer using well known reference accelerometer in laboratory tests. The procedures of both methods have been discussed and validations of these methods have been presented through experimental examples. In addition, a Finite Element (FE) model of a typical MEMS accelerometer has been developed and modal analysis has been carried out to understand the dynamics of capacitive type MEMS accelerometer and to identify the source of errors. It has been observed that the moving fingers behave like a cantilever beam while the fixed fingers showed rigid body motion. This cantilever type of motion seems to be causing non-parallel plates effect in the formed capacitors between moving and fixed fingers which results in errors in the vibration measurement. Hence, design modifications on finger shape have been suggested to remove the cantilever motion and results showed remarkable improvement. Moreover, the effect of using synchronous amplitude modulation and demodulation in the readout circuit has been studied. The experimental study showed that this circuit also introduces errors in amplitude and phase of the output signal compared with the input signal. Thus, in the new design of MEMS accelerometers, improvements in both mechanical design and electronic circuit are required.

Microstructure manipulation is a fundamental process to the study of biology and medicine, as well as to advance micro- and nano-system applications. Manipulation of microstructures has been achieved through various microgripper devices developed recently, which lead to advances in micromachine assembly, and single cell manipulation, among others. Only two kinds of integrated feedback have been demonstrated so far, force sensing and optical binary feedback. As a result, the physical, mechanical, optical, and chemical information about the microstructure under study must be extracted from macroscopic instrumentation, such as confocal fluorescence microscopy and Raman spectroscopy. In this research work, novel Micro-Opto-Electro-Mechanical-System (MOEMS) microgrippers are presented. These devices utilize flexible optical waveguides as gripping arms, which provide the physical means for grasping a microobject, while simultaneously enabling light to be delivered and collected. This unique capability allows extensive optical characterization of the structure being held such as transmission, reflection, or fluorescence. The microgrippers require external actuation which was accomplished by two methods: initially with a micrometer screw, and later with a piezoelectric actuator. Thanks to a novel actuation mechanism, the “fishbone”, the gripping facets remain parallel within 1 degree. The design, simulation, fabrication, and characterization are systematically presented. The devices mechanical operation was verified by means of 3D finite element analysis simulations. Also, the optical performance and losses were simulated by the 3D-to-2D effective index (finite difference time domain FDTD) method as well as 3D Beam Propagation Method (3D-BPM). The microgrippers were designed to manipulate structures from submicron dimensions up to approximately 100 µm. The devices were implemented in SU-8 due to its suitable optical and mechanical properties. This work demonstrates two practical applications: the manipulation of single SKOV-3 human ovarian carcinoma cells, and the detection and identification of microparts tagged with a fluorescent “barcode” implemented with quantum dots. The novel devices presented open up new possibilities in the field of micromanipulation at the microscale, scalable to the nano-domain.

No description available.

Les travaux menés durant cette thèse ont pour objectif d’améliorer les performances des systèmes hybrides GNSS/MEMS. Ils se décomposent en deux parties distinctes : d’une part, le développement d’un ensemble de traitement capteurs cherchant à améliorer la mesure elle-même et d’autre part, l’optimisation des algorithmes d’hybridation pour les capteurs MEMS de Thales. Le traitement capteur consiste en l’estimation de l’accélération vraie (resp. la vitesse angulaire vraie) à partir de la sortie du capteur accélérométrique (resp. gyrométrique). Ce traitement a été réalisé en deux sous-étapes : 1) La calibration qui consiste en l’identification du système non-linéaire connaissant ses entrées et ses sorties. Les relations entrant en jeu dans le modèle étant linéaires vis-à-vis des paramètres, on peut alors résoudre cette partie du problème par l’estimateur des moindres carrés (après extension du vecteur comprenant les entrées afin qu’il comporte les non linéarités). 2) L’inversion du modèle qui a pour but d’estimer les entrées du modèle connaissant ses sorties et l’estimation des paramètres effectuée durant l’étape de calibration. Après formalisation de ce problème sous forme d’un modèle dynamique, la résolution se fera à l’aide d’algorithme type filtre de Kalman ou filtre particulaire. Les algorithmes d’hybridation ont pour but de localiser un mobile dans l’espace connaissant l’information issue des MEMS ainsi que celle apportée par le GPS. Cette partie peut également se décomposer en deux sous-problèmes : 1) Lorsque que les signaux GPS sont disponibles (cas nominal), le but est d’améliorer les méthodes de navigation hybride GPS/INS existantes (EKF, UKF, PF, …). Dans notre cas, la réflexion a portée sur une modélisation à l’ordre 2 des biais des capteurs MEMS et sur la fermeture de la boucle de navigation (correction de la centrale inertielle à l’aide des erreurs issues du filtre d’hybridation). 2) Dans des scénarii défavorables (multitrajet et masquage des signaux GPS), la qualité des capteurs MEMS ne permet pas d’obtenir des résultats de navigation satisfaisants. Un algorithme basé sur un réseau de neurones a donc été développé. Durant les phases où le GPS est disponible, cet algorithme permet d’apprendre l’erreur commise par la centrale inertielle en mode survie par rapport au résultat de navigation hybride. Le réseau de neurones ainsi appris fournira alors cet élément de correction en cas de perte de l’information GPS. Ces différentes méthodes ont permis d’accroître la précision de la navigation GNSS/MEMS aussi bien dans le cas nominal que lors de pertes du signal GPS / The goal of this thesis is to improve accuracy of GNSS/MEMS integrated navigation system. Two main parts can be distinguished in this thesis: first, sensor processing can be achieved to improve measurement accuracy and then, navigation algorithm can be optimized for the specific case of MEMS sensors. Sensor processing is the estimation of real acceleration (resp. real angular rate) from the one measured by accelerometer (resp. gyrometer). This processing have been realized in two steps: 1) Calibration: identification of the non-linear system describing sensors (resolved by Least Square method). 2) Model inversion: estimation of the input of the non-linear system, i.e. acceleration and/or angular rate (resolved by Kalman filtering). Navigation algorithm have then to locate an object in space from both GNSS and MEMS data. This part have been also realized in two steps: 1) If GNSS signals are available, the goal is to improve the existing GNSS/INS navigation schemes (2nd-order bias modeling of MEMS sensors). 2) If GNSS are not available (e.g. multipath or outage), a Neural Network based algorithm have been developped, which learn the error made by the inertial platform during the unavailability of GNSS signals. These different methods have allowed to improve accuracy of GNSS/MEMS inetgrated navigation system both for nominal case and degraded case

Advancements in the micro-and nano-scale fabrication techniques have opened up new avenues for the development of portable, scalable and easier-to-use biosensors. Over the last few years, electrodes made of carbon have been widely used as sensing units in biosensors due to their attractive physiochemical properties. The aim of this research is to investigate different strategies to develop functionalized high surface carbon micro/nano-structures for electrochemical and biosensing devices. High aspect ratio three-dimensional carbon microarrays were fabricated via carbon microelectromechanical systems (C-MEMS) technique, which is based on pyrolyzing pre-patterned organic photoresist polymers. To further increase the surface area of the carbon microstructures, surface porosity was introduced by two strategies, i.e. (i) using F127 as porogen and (ii) oxygen reactive ion etch (RIE) treatment. Electrochemical characterization showed that porous carbon thin film electrodes prepared by using F127 as porogen had an effective surface area (Aeff 185%) compared to the conventional carbon electrode. To achieve enhanced electrochemical sensitivity for C-MEMS based functional devices, graphene was conformally coated onto high aspect ratio three-dimensional (3D) carbon micropillar arrays using electrostatic spray deposition (ESD) technique. The amperometric response of graphene/carbon micropillar electrode arrays exhibited higher electrochemical activity, improved charge transfer and a linear response towards H2O2 detection between 250μM to 5.5mM. Furthermore, carbon structures with dimensions from 50 nano-to micrometer level have been fabricated by pyrolyzing photo-nanoimprint lithography patterned organic resist polymer. Microstructure, elemental composition and resistivity characterization of the carbon nanostructures produced by this process were very similar to conventional photoresist derived carbon. Surface functionalization of the carbon nanostructures was performed using direct amination technique. Considering the need for requisite functional groups to covalently attach bioreceptors on the carbon surface for biomolecule detection, different oxidation techniques were compared to study the types of carbon–oxygen groups formed on the surface and their percentages with respect to different oxidation pretreatment times. Finally, a label-free detection strategy using signaling aptamer/protein binding complex for platelet-derived growth factor oncoprotein detection on functionalized three-dimensional carbon microarrays platform was demonstrated. The sensor showed near linear relationship between the relative fluorescence difference and protein concentration even in the sub-nanomolar range with an excellent detection limit of 5 pmol.

La presente tesis toma como eje central el modelado de sistemas dinámicos mediante Autómatas Celulares (ACs). Los ACs permiten modelar un sistema enunciando el comportamiento microscópico a fin de obtener un comportamiento macroscópico correcto. Una de los principales campos donde esta metodología ha sido aplicada (y la cual forma otro de los puntos centrales de esta tesis) es el modelado del Grabado Anisótropo Húmedo (GAH). El GAH es un proceso químico el cual permite realizar microestructuras de silicio tridimensionales, lo que le ha permitido convertirse en una importante técnica de microfabricación. El GAH se utiliza para el micromaquinado de Sistemas Micro-Electro-Mecánicos (MEMS). Los MEMS consisten en la integración de elementos mecánicos, sensores, actuadores y electrónica en un substrato de silicio común a través de la tecnología de microfabricación. Los MEMS tienen una gran influencia en la industria puesto que dispositivos fabricados mediante esta tecnología se utilizan de forma intensiva en diversos campos tales como: sistemas de seguridad en automoción, sensores de movimiento en electrónica de consumo o inyectores en sistemas de impresión. El GAH es un proceso complejo cuyo resultado depende en gran medida de los diversos parámetros del proceso: (disolución, temperatura, tiempo), por lo que la utilización de un simulador previo a la realización del experimento puede suponer un gran ahorro en cuestión de tiempo y material. Los simuladores actuales de GAH basados en ACs poseen diversas limitaciones: Tiempos de computación muy elevados debido a los altos requisitos computacionales de los ACs, un reducido conjunto de calibraciones existentes, así como la imposibilidad de simular el GAH basado en nuevos atacantes tales como TMAH+Triton. La resolución de estas limitaciones es abordada en diversos capítulos de la tesis. / Ferrando Jódar, N. (2011). Estudio, Modelado e Implementación Paralela de Sistemas Celulares Utilizados en Microfabricación [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/10984 / Palancia

Two dimensional (2D) materials can withstand an order of magnitude more strain than their bulk counterparts, which results in dramatic changes to electrical, thermal and optical properties. These changes can be harnessed for technological applications such as tunable light emitting diodes or field effect transistors, or utilized to explore novel physics like exciton confinement, pseudo-magnetic fields (PMFs), and even quantum gravity. However, current techniques for straining atomically thin materials offer limited control over the strain field, and require bulky pressure chambers or large beam bending equipment. This dissertation describes the development of micro-electromechanical systems (MEMS) as a platform for precisely controlling the magnitude and orientation of the strain field in 2D materials. MEMS are a versatile platform for studying strain physics. Mechanical, electrical, thermal and optical probes can all be easily incorporated into their design. Further, because of their small size and compatibility with electronics manufacturing methods, there is an achievable pathway from the laboratory bench to real-world application. Nevertheless, the incorporation of atomically thin crystals with MEMS has been hampered by fragile, non-planer structures and low friction interfaces. We have innovated two techniques to overcome these critical obstacles: micro-structure assisted transfer to place the 2D materials on the MEMS gently and precisely, and micro-riveting to create a slip-free interface between the 2D materials and MEMS. With these advancements, we were able to strain monolayer molybdenum disulfide (MoS2) to greater than 1\% strain with a MEMS for the first time. The dissertation develops the theoretical underpinnings of this result including original work on the theory of operation of MEMS chevron actuators, and strain generated PMFs in transition metal dichalcogenides, a large class of 2D materials. We conclude the dissertation with a roadmap to guide and inspire future physicists and engineers exploring strain in 2D systems and their applications. The roadmap contains ideas for next-generation fabrication techniques to improve yield, sample quality, and add capabilities. We have also included in the roadmap proposals for experiments such as a speculative technique for realizing topological quantum field theories that mimics recent theoretical wire construction methods.

abstract: BioMEMS has the potential to provide many future tools for life sciences, combined with microfabrication technologies and biomaterials. Especially due to the recent corona 19 epidemic, interest in BioMEMS technology has increased significantly, and the related research has also grown significantly. The field with the highest demand for BioMEMS devices is in the medical field. In particular, the implantable device field is the largest sector where cutting-edge BioMEMS technology is applied along with nanotechnology, artificial intelligence, genetic engineering, etc. However, implantable devices used for brain diseases are still very limited because unlike other parts of human organs, the brain is still unknow area which cannot be completely replaceable.To date, the most commercially used, almost only, implantable device for the brain is a shunt system for the treatment of hydrocephalus. The current cerebrospinal fluid (CSF) shunt treatment yields high failure rates: ~40% within first 2 years and 98% within 10 years. These failures lead to high hospital admission rates and repeated invasive surgical procedures, along with reduced quality of life. New treatments are needed to improve the disease burden associated with hydrocephalus. In this research, the proposed catheter-free, completely-passive miniaturized valve is designed to alleviate hydrocephalus at the originating site of the disorder and diminish failure mechanisms associated with current treatment methods. The valve is composed of hydrogel diaphragm structure and polymer or glass outer frame which are 100% bio-compatible material. The valve aims to be implanted between the sub-arachnoid space and the superior sagittal sinus to regulate the CSF flow substituting for the obstructed arachnoid granulations. A cardiac pacemaker is one of the longest and most widely used implantable devices and the wireless technology is the most widely used with it for easy acquisition of vital signs and rapid disease diagnosis without clinical surgery. But the conventional pacemakers with some wireless technology face some essential complications associated with finite battery life, ultra-vein pacing leads, and risk of infection from device pockets and leads. To solve these problems, wireless cardiac pacemaker operating in fully-passive modality is proposed and demonstrates the promising potential by realizing a prototype and functional evaluating. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020

The objective of this dissertation is to investigate several dynamical approaches aiming to improve the sensitivity and performance of microelectromechanical systems (MEMS) resonant sensors. Resonant sensors rely on tracking shifts in the dynamic features of microstructures during sensing, such as their resonance frequency. We aim here to demonstrate analytically and experimentally several new concepts aiming to sharpen their response, enhance the signal to noise ratio, and demonstrate smart functionalities combined into a single resonator. The dissertation starts with enhancing the excitations of the higher order modes of vibrations of clamped-clamped microbeam resonators. The concept is based on using partial electrodes with shapes that induce strong excitation of the mode of interest. Using a half electrode, the second mode is excited with a high amplitude of vibration. Also, using a two-third electrode configuration is shown to amplify the third mode resonance amplitude compared with the full electrode under the same electrical loading conditions. Then, we demonstrate the effectiveness of higher order mode excitation and metal organic frameworks (MOFs) functionalization for improving the sensitivity and selectivity of resonant gas sensors. Also, using a single mode only, we show the possibility of realizing a smart switch triggered upon exceeding a threshold mass when operating the resonator near the dynamic pull-in instability. The second part of the dissertation deals with the dynamics of the microbeam under a two-source harmonic excitation. We experimentally demonstrate resonances of an additive and subtractive type. It is shown that by properly tuning the frequency and amplitude of the excitation force, the frequency bandwidth of the resonator is controlled. Finally, we employ the multimode excitation of a single resonator to demonstrate smart functionalities. By monitoring the frequency shifts of two modes, we experimentally demonstrate the effectiveness of this technique to measure the environmental temperature and gas concentration. Also, we present a hybrid sensor and switch device, which is capable of accurately measuring gas concentration and perform switching when the concentration exceeds a specific (safe) threshold. In contrast to the single mode operation, we show that monitoring the third mode enhances sensitivity, improves accuracy, and lowers the sensor sensitivity to noise.