Programmable Multistable Mechanisms: Design, modeling, characterization and applications

Multistable Mechanisms are mechanical devices having more than one stable state. Since these mechanisms can maintain different deformations with zero force, they are advantageous for low power environments such as wristwatches and medical devices. In this thesis, I introduce programmable multistable mechanisms (PMMs), a new family of multistable mechanisms where the number, position, and stiffness of stable states can be controlled by programming inputs modifying the boundary conditions. PMMs can be synthesized by combining bistable mechanisms. This method was used to produce the T-mechanism, a PMM consisting of two double parallelogram mechanisms (DPMs) connected orthogonally where each DPM consists of two parallel beams connected centrally by a rigid block and axially loaded by programming input. An analytical model based on Euler-Bernoulli beam theory was derived to describe qualitatively the stability behaviour of the T-mechanism. The model approximates the mechanism's stiffness by a sixth order polynomial from which the reaction force and strain energy expressions can be estimated. These explicit formulas provide analytical expressions for the number, position, and stiffness of stable and unstable states as functions of the programming inputs. The qualitative stability behavior was represented by the programming diagram, bifurcation diagrams and stiffness maps relating the number, position and stiffness of stable states with the programming inputs. In addition, I showed that PMMs have zero stiffness regions functioning as constant-force multistable mechanisms. Numerical simulations validated these results. Experimental measurements were conducted on the T-mechanism prototype manufactured using electro-discharge machining. An experimental setup was built to measure the reaction force of the mechanism for different programming inputs. I verified the possible configurations of the T-mechanism including monostability bistability, tristability, quadrastability, zero stiffness regions, validating my analytical and numerical models. Compared to classical multistable mechanisms which are displaced between their stable states by imposing a direct displacement, PMMs can be displaced by modifying mechanism strain energy. This property increases the repeatability of the mechanism as the released energy is independent of the driving parameters, which can be advantageous for mechanical watches and medical devices. Accurate timekeepers require oscillators having repeatable period independent of their energy source. However, the balance wheel spiral spring oscillator used in all mechanical watches, suffers from isochronism defect, i.e., its oscillation period depends on its amplitude. I addressed this problem by introducing novel detached constant force escapements for mechanical wristwatches based on PMMs. In the medical domain, I applied PMMs to construct a retinal vein cannulation needle for the treatment of retinal vein occlusion. PMMs based needles produce sufficient repeatable puncturing energy with a predefined stroke independent of the operator input. Numerical simulations were used to model and dimension our proposed tool and satisfy the strict requirements of ophthalmologic operations. The tool was manufactured using 3D femto-laser printing of glass. An experimental setup was built to characterize the tool's mechanical behavior and to verify my computations. The tool was applied successfully to cannulate retinal veins of pig eyes

Development of MEMS Piezoelectric Vibration Energy Harvesters with Wafer-Level Integrated Tungsten Proof-Mass for Ultra Low Power Autonomous Wireless Sensors

La génération d’énergie localisée et à petite échelle, par transformation de l’énergie vibratoire disponible dans l’environnement, est une solution attrayante pour améliorer l’autonomie de certains noeuds de capteurs sans-fil pour l’Internet des objets (IoT). Grâce à des microdispositifs inertiels résonants piézoélectriques, il est possible de transformer l’énergie mécanique en électricité. Cette thèse présente une étude exhaustive de cette technologie et propose un procédé pour fabriquer des microgénérateurs MEMS offrant des performances surpassant l’état de l’art. On présente d’abord une revue complète des limites physiques et technologiques pour identifier le meilleur chemin d’amélioration. En évaluant les approches proposées dans la littérature (géométrie, architecture, matériaux, circuits, etc.), nous suggérons des métriques pour comparer l’état de l’art. Ces analyses démontrent que la limite fondamentale est l’énergie absorbée par le dispositif, car plusieurs des solutions existantes répondent déjà aux autres limites. Pour un générateur linéaire résonant, l’absorption d’énergie dépend donc des vibrations disponibles, mais aussi de la masse du dispositif et de son facteur de qualité. Pour orienter la conception de prototypes, nous avons réalisé une étude sur le potentiel des capteurs autonomes dans une automobile. Nous avons évalué une liste des capteurs présents sur un véhicule pour leur compatibilité avec cette technologie. Nos mesures de vibrations sur un véhicule en marche aux emplacements retenus révèlent que l’énergie disponible pour un dispositif linéaire résonant MEMS se situe entre 30 à 150 Hz. Celui-ci pourrait produire autour de 1 à 10 μW par gramme. Pour limiter la taille d’un générateur MEMS pouvant produire 10 μW, il faut une densité supérieure à celle du silicium, ce qui motive l’intégration du tungstène. L’effet du tungstène sur la sensibilité du dispositif est évident, mais nous démontrons également que l’usage de ce matériau permet de réduire l’impact de l’amortissement fluidique sur le facteur de qualité mécanique Qm. En fait, lorsque l’amortissement fluidique domine, ce changement peut améliorer Qm d’un ordre de grandeur, passant de 103 à 104 dans l’air ambiant. Par conséquent, le rendement du dispositif est amélioré sans utiliser un boîtier sous vide. Nous proposons ensuite un procédé de fabrication qui intègre au niveau de la tranche des masses de tungstène de 500 μm d’épais. Ce procédé utilise des approches de collage de tranches et de gravure humide du métal en deux étapes. Nous présentons chaque bloc de fabrication réalisé pour démontrer la faisabilité du procédé, lequel a permis de fabriquer plusieurs prototypes. Ces dispositifs ont été testés en laboratoire, certains démontrant des performances records en terme de densité de puissance normalisée. Notre meilleur design se démarque par une métrique de 2.5 mW-s-1/(mm3(m/s2)2), soit le meilleur résultat répertorié dans l’état de l’art. Avec un volume de 3.5 mm3, il opère à 552.7 Hz et produit 2.7 μW à 1.6 V RMS à partir d’une accélération de 1 m/s2. Ces résultats démontrent que l’intégration du tungstène dans les microgénérateurs MEMS est très avantageuse et permet de s’approcher davantage des requis des applications réelles.Small scale and localized power generation, using vibration energy harvesting, is considered as an attractive solution to enhance the autonomy of some wireless sensor nodes used in the Internet of Things (IoT). Conversion of the ambient mechanical energy into electricity is most often done through inertial resonant piezoelectric microdevices. This thesis presents an extensive study of this technology and proposes a process to fabricate MEMS microgenerators with record performances compared to the state of the art. We first present a complete review of the physical and technological limits of this technology to asses the best path of improvement. Reported approaches (geometries, architectures, materials, circuits) are evaluated and figures of merit are proposed to compare the state of the art. These analyses show that the fundamental limit is the absorbed energy, as most proposals to date partially address the other limits. The absorbed energy depends on the level of vibrations available, but also on the mass of the device and its quality factor for a linear resonant generator. To guide design of prototypes, we conducted a study on the potential of autonomous sensors in vehicles. A survey of sensors present on a car was realized to estimate their compatibility with energy harvesting technologies. Vibration measurements done on a running vehicle at relevant locations showed that the energy available for MEMS devices is mostly located in a frequency range of 30 to 150 Hz and could generate power in the range of 1-10 μW per gram from a linear resonator. To limit the size of a MEMS generator capable of producing 10 μW, a higher mass density compared to silicon is needed, which motivates the development of a process that incorporates tungsten. Although the effect of tungsten on the device sensitivity is well known, we also demonstrate that it reduces the impact of the fluidic damping on the mechanical quality factor Qm. If fluidic damping is dominant, switching to tungsten can improve Qm by an order of magnitude, going from 103 to 104 in ambient air. As a result, the device efficiency is improved despite the lack of a vacuum package. We then propose a fabrication process flow to integrate 500 μm thick tungsten masses at the wafer level. This process combines wafer bonding with a 2-step wet metal etching approach. We present each of the fabrication nodes realized to demonstrate the feasibility of the process, which led to the fabrication of several prototypes. These devices are tested in the lab, with some designs demonstrating record breaking performances in term of normalized power density. Our best design is noteworthy for its figure of merit that is around 2.5 mW-s-1/(mm3(m/s2)2), which is the best reported in the state of the art. With a volume of 3.5 mm3, it operates at 552.7 Hz and produces 2.7 μW at 1.6 V RMS from an acceleration of 1 m/s2. These results therefore show that tungsten integration in MEMS microgenerators is very advantageous, allowing to reduce the gap with needs of current applications

A History of Materials and Technologies Development

The purpose of the book is to provide the students with the text that presents an introductory knowledge about the development of materials and technologies and includes the most commonly available information on human development. The idea of the publication has been generated referring to the materials taken from the organic and non-organic evolution of nature. The suggested texts might be found a purposeful tool for the University students proceeding with studying engineering due to the fact that all subjects in this particular field more or less have to cover the history and development of the studied object. It is expected that studying different materials and technologies will help the students with a better understanding of driving forces, positive and negative consequences of technological development, etc

Psr1p interacts with SUN/sad1p and EB1/mal3p to establish the bipolar spindle

Regular Abstracts - Sunday Poster Presentations: no. 382During mitosis, interpolar microtubules from two spindle pole bodies (SPBs) interdigitate to create an antiparallel microtubule array for accommodating numerous regulatory proteins. Among these proteins, the kinesin-5 cut7p/Eg5 is the key player responsible for sliding apart antiparallel microtubules and thus helps in establishing the bipolar spindle. At the onset of mitosis, two SPBs are adjacent to one another with most microtubules running nearly parallel toward the nuclear envelope, creating an unfavorable microtubule configuration for the kinesin-5 kinesins. Therefore, how the cell organizes the antiparallel microtubule array in the first place at mitotic onset remains enigmatic. Here, we show that a novel protein psrp1p localizes to the SPB and plays a key role in organizing the antiparallel microtubule array. The absence of psr1+ leads to a transient monopolar spindle and massive chromosome loss. Further functional characterization demonstrates that psr1p is recruited to the SPB through interaction with the conserved SUN protein sad1p and that psr1p physically interacts with the conserved microtubule plus tip protein mal3p/EB1. These results suggest a model that psr1p serves as a linking protein between sad1p/SUN and mal3p/EB1 to allow microtubule plus ends to be coupled to the SPBs for organization of an antiparallel microtubule array. Thus, we conclude that psr1p is involved in organizing the antiparallel microtubule array in the first place at mitosis onset by interaction with SUN/sad1p and EB1/mal3p, thereby establishing the bipolar spindle.postprin

Removal of antagonistic spindle forces can rescue metaphase spindle length and reduce chromosome segregation defects

Regular Abstracts - Tuesday Poster Presentations: no. 1925Metaphase describes a phase of mitosis where chromosomes are attached and oriented on the bipolar spindle for subsequent segregation at anaphase. In diverse cell types, the metaphase spindle is maintained at a relatively constant length. Metaphase spindle length is proposed to be regulated by a balance of pushing and pulling forces generated by distinct sets of spindle microtubules and their interactions with motors and microtubule-associated proteins (MAPs). Spindle length appears important for chromosome segregation fidelity, as cells with shorter or longer than normal metaphase spindles, generated through deletion or inhibition of individual mitotic motors or MAPs, showed chromosome segregation defects. To test the force balance model of spindle length control and its effect on chromosome segregation, we applied fast microfluidic temperature-control with live-cell imaging to monitor the effect of switching off different combinations of antagonistic forces in the fission yeast metaphase spindle. We show that spindle midzone proteins kinesin-5 cut7p and microtubule bundler ase1p contribute to outward pushing forces, and spindle kinetochore proteins kinesin-8 klp5/6p and dam1p contribute to inward pulling forces. Removing these proteins individually led to aberrant metaphase spindle length and chromosome segregation defects. Removing these proteins in antagonistic combination rescued the defective spindle length and, in some combinations, also partially rescued chromosome segregation defects. Our results stress the importance of proper chromosome-to-microtubule attachment over spindle length regulation for proper chromosome segregation.postprin

Safety and Reliability - Safe Societies in a Changing World

The contributions cover a wide range of methodologies and application areas for safety and reliability that contribute to safe societies in a changing world. These methodologies and applications include: - foundations of risk and reliability assessment and management - mathematical methods in reliability and safety - risk assessment - risk management - system reliability - uncertainty analysis - digitalization and big data - prognostics and system health management - occupational safety - accident and incident modeling - maintenance modeling and applications - simulation for safety and reliability analysis - dynamic risk and barrier management - organizational factors and safety culture - human factors and human reliability - resilience engineering - structural reliability - natural hazards - security - economic analysis in risk managemen

MS FT-2-2 7 Orthogonal polynomials and quadrature: Theory, computation, and applications

Quadrature rules find many applications in science and engineering. Their analysis is a classical area of applied mathematics and continues to attract considerable attention. This seminar brings together speakers with expertise in a large variety of quadrature rules. It is the aim of the seminar to provide an overview of recent developments in the analysis of quadrature rules. The computation of error estimates and novel applications also are described

Generalized averaged Gaussian quadrature and applications

A simple numerical method for constructing the optimal generalized averaged Gaussian quadrature formulas will be presented. These formulas exist in many cases in which real positive GaussKronrod formulas do not exist, and can be used as an adequate alternative in order to estimate the error of a Gaussian rule. We also investigate the conditions under which the optimal averaged Gaussian quadrature formulas and their truncated variants are internal