Parallel-plate electrostatic actuators driven by a voltage difference between two electrodes suffer from an operation range limited to 30% of the gap that has significantly restrained their applications in Microelectromechanical systems (MEMS). In this thesis, the travel range of an electrostatic actuator made of a micro-cantilever beam electrode above a fixed electrode is extended quasi-statically to 90% of the capacitor gap by introducing a voltage regulator (controller) circuit designed for low frequency actuation. The developed large-stroke actuator is valuable contribution to applications in optical filters, optical modulators, digital micro-mirrors and micro-probe based memory disk drives. To implement the low-frequency large-stroke actuator, the beam tip velocity is measured by a vibrometer, the corresponding signal is integrated in the regulator circuit to obtain the displacement feedback, which is used to modify the input voltage of the actuator to reach a target location. The voltage regulator reduces the total voltage, and therefore the electrostatic force, once the beam approaches the fixed electrode so that the balance is maintained between the mechanical restoring force and the electrostatic force that enables the actuator to achieve the desired large stroke. A mathematical model is developed for the actuator based on the mode shapes of the cantilever beam using experimentally identified parameters that yields good accuracy in predicting both the open loop and the closed loop responses. The low-frequency actuator also yields superharmonic resonances that are observed here for the first time in electrostatic actuators. The actuator can also be configured either as a bi-stable actuator using a low-frequency controller or as a chaotic resonator using a high-frequency controller. The high-frequency controller yields large and bounded chaotic attractors for a wide range of excitation magnitudes and frequencies making it suitable for sensor applications. Bifurcation diagrams reveal periodic motions, softening behavior, period doubling cascades, one-well and two-well chaos, superharmonic resonances and a reverse period doubling cascade. To verify the observed chaotic oscillations, Lyapunov exponents are calculated and found to be positive. Furthermore, a chaotic resonator with a quadratic controller is designed that not only requires less voltage, but also produces more robust and larger motions. Another metric of chaos, information entropy, is used to verify the chaotic attractors in this case. It is found that the attractors have a common information entropy of 0.732 independent of the excitation amplitude and frequency.

Parallel-plate electrostatic actuators driven by a voltage difference between two electrodes suffer from an operation range limited to 30% of the gap that has significantly restrained their applications in Microelectromechanical systems (MEMS). In this thesis, the travel range of an electrostatic actuator made of a micro-cantilever beam electrode above a fixed electrode is extended quasi-statically to 90% of the capacitor gap by introducing a voltage regulator (controller) circuit designed for low frequency actuation. The developed large-stroke actuator is valuable contribution to applications in optical filters, optical modulators, digital micro-mirrors and micro-probe based memory disk drives. To implement the low-frequency large-stroke actuator, the beam tip velocity is measured by a vibrometer, the corresponding signal is integrated in the regulator circuit to obtain the displacement feedback, which is used to modify the input voltage of the actuator to reach a target location. The voltage regulator reduces the total voltage, and therefore the electrostatic force, once the beam approaches the fixed electrode so that the balance is maintained between the mechanical restoring force and the electrostatic force that enables the actuator to achieve the desired large stroke. A mathematical model is developed for the actuator based on the mode shapes of the cantilever beam using experimentally identified parameters that yields good accuracy in predicting both the open loop and the closed loop responses. The low-frequency actuator also yields superharmonic resonances that are observed here for the first time in electrostatic actuators. The actuator can also be configured either as a bi-stable actuator using a low-frequency controller or as a chaotic resonator using a high-frequency controller. The high-frequency controller yields large and bounded chaotic attractors for a wide range of excitation magnitudes and frequencies making it suitable for sensor applications. Bifurcation diagrams reveal periodic motions, softening behavior, period doubling cascades, one-well and two-well chaos, superharmonic resonances and a reverse period doubling cascade. To verify the observed chaotic oscillations, Lyapunov exponents are calculated and found to be positive. Furthermore, a chaotic resonator with a quadratic controller is designed that not only requires less voltage, but also produces more robust and larger motions. Another metric of chaos, information entropy, is used to verify the chaotic attractors in this case. It is found that the attractors have a common information entropy of 0.732 independent of the excitation amplitude and frequency.

Hydro power plants are an essential part of the infrastructure in Sweden as they stand for a large amount of the produced electricity and are used to regulate supply and demand on the electricity grid. Other renewable energy sources, such as wind and solar power, have become more popular as they contribute to a fossil free society. However, wind and solar power are intermittent energy sources causing the demand for regulating power on the grid to increase. Hydro power turbines are designed to operate at a certain design point with a specific flow rate. The plants are operated away from the design point when used to regulate the supply and demand of electricity. This can cause a specific flow phenomenon to arise in the draft tube at part load conditions called a Rotating Vortex Rope (RVR) which causes dangerous pressure fluctuation able to damage blades and bearings. A solution to mitigate a RVR is to inject pulsating momentum into the draft tube by using an actuator operating at a certain frequency. A literature study was conducted and three techniques were numerically simulated using ANSYS Workbench 19.0 R3; a fluidic oscillator, a piston actuator and a synthetic jet actuator. A dynamic mesh was used to simulate the movement of the piston actuator and diaphragm of the synthetic actuator whilst the mesh of the fluidic oscillator was stationary. The relative errors of the three numerical models were all below 3 %. All devices showed promising results and could potentially be used to mitigate a RVR because they all have the ability to produce high energy jets. The fluidic oscillator had an external supply of water, whereas the other two did not, which means that it could inject the largest mass flow. The piston actuator required a driving motor to move the piston. The diaphragm of the synthetic jet actuator was moved by a Piezoelectric element. Advantages of the fluidic oscillator are that it has no moving parts, in contrary to the two other devices, it can directly be connected to the penstock or draft tube to obtain the required water supply and it is easy to install. It will most likely also be smaller compared to the other two for the same mass flow rate. It does however not generate a pulsating jet, but rather an oscillating jet. The other two devices generate pulsating jets, but have problems with low pressure areas during the intake stroke which can cause cavitation problems. These areas cause the formation of vortex rings close to the outlet. Simulations showed that a coned piston together with a coned cylinder outlet could decrease losses by almost 16 % compared to a normal piston and cylinder. It also decreased the risk for cavitation and the required force to move the piston. Otherwise, a shorter stroke length for a constant cylinder diameter or a longer stroke length for a constant volume displacement also decreased the risk for cavitation and required force. The gasket between the piston and cylinder is a potential risk for leakage. A solution to avoid critical low pressure areas is to install an auxiliary fluid inlet or valve which opens at a certain pressure for the piston actuator as well as the synthetic jet actuator. This will also allow larger mass flow rates and a higher injected momentum. Both devices are more complicated to install and require likely more maintenance compared to the fluidic oscillator. However, there exist many possible design options for the piston actuator. The design of the synthetic jet is more limited because of the diaphragm. The amplitude of the diaphragm also has a direct effect on the pressure levels. The losses increased proportional to the mass flow to the power of three which suggests that it is better to install many small actuators instead of a few large ones.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / This paper discusses a “Smart Sensor” interface being developed for use in the Boeing Company. Several laboratory groups and Flight Test have joined in a study to define such an interface. It will allow a data acquisition system to record data from a large number of “Smart Sensors”. A single pair of wires will form a bus to interface the sensors to the data system. Most systems will need more than one bus. Some needs exist for "Smart Actuators" as well to allow for closed loop control within the laboratories. The process control industry has developed several candidate busses. The groups are now in the process of evaluating the capabilities of the available busses to see which ones, if any, will do our job. To see if anyone else has similar needs, these requirements and the candidate busses are being shared. The goal is to see if some form of cooperation is possible.

It is well known in medicine that changes in tissue elasticity may be related to pathological phenomena such as cancer and other disease. Physicians routinely use palpation as means of inspecting the thyroid, prostate, and breast, where a palpably hard mass can often indicate the presence of a malignant lesion. Magnetic Resonance Elastography (MRE) has emerged as a relatively new elasticity imaging technique which can be used to spatially map and measure displacement patterns resulting from harmonic shear-wave propagation in soft tissue. Displacement fields are then used in reconstructing the tissue’s elastic property distributions. The feasibility of using MRE as a noninvasive means of characterizing the mechanical properties of silicone phantom mimicking human breast, was investigated though experiments involving MRE acquisitions of four phantoms. To achieve sufficient excitation of the phantom tissue, an acoustic actuator was developed. The results of these studies have shown the MRE acquisition to be successful in capturing sufficient data for elastic parameter reconstruction. Another different type of actuator has been developed and tested in the laboratory. The results show the potential for future use of this actuator in MRE experiments.

This dissertation describes the development of an assist-device aimed to deliver 3D graphic information to the visually impaired people. A human-in-loop approach was used to analyze whether a virtual 3D shape can be transferred correctly to the human users.The proposed device in this dissertation consists of two major parts: (a) A system of position sensors for real time localization based on magnetization, and (b) A single vibratory actuator working at varied frequencies based on its real time location. The error bound of the position measurement was tested to be 2 mm, which defined the machine resolution of the shape display. In order to realize the refresh rate of the localization that can follow user's scanning speed, the parallel data processing sequences for computer and microcontroller were designed. Additionally, vibratory electromagnetic (EM) actuators were discussed based on eddy current and permanent magnet methods. The simulation study showed that eddy current method was not applicable for millimeter size coil. Accordingly, the permanent magnet method was developed and the force detection threshold of human tactile perceptions was studied.Virtual shape perception experiments were made with participation of 3 volunteers who were not aware of the 3D shape information prior to the tests. Based on the four sets of shape tests, we conclude that the majority of the shape information is able to be delivered to users by using the proposed device. Difficulties for perceiving the local sharp profile e.g. thin plates and large curvature in small shapes may be better addressed by multiple actuators simultaneously providing shape information in the local boundary detection.The major contribution of this dissertation is the 3D shape display implemented by a miniature and low cost device. The developed device utilizes both passive stimulation and active search so that a commonly used large scale actuators matrix based on mere active touch method is avoided. The studies on the required force/energy input from the actuator showed that EM actuators can be miniaturized to millimeter scale without sacrificing the ability to induce tactile stimulation. Additional uniqueness of the proposed system is the ability to present hollow features, which is impossible to display by the existing devices.

In this thesis, some fundamentals and possible applications of high-pressure microfluidics have been explored. Furthermore, handling fluids at high pressures has been addressed, specifically by creating and characterizing strong microvalves and pumps. A variety of microstructuring techniques was used to realize these microfluidic devices, e.g., etching, lithography, and bonding. To be able to handle high pressures, the valves and pumps need to be strong. This necessitates a strong actuator material. In this thesis, the material of choice is paraffin wax. A new way of latching paraffin-actuated microvalves into either closed or open position has been developed, using the low thermal conductivity of paraffin to create large thermal gradients within a microactuator. This allows for long open and closed times without power consumption. In addition, three types of paraffin-actuated pumps are presented: A peristaltic high-pressure pump with integrated temperature control, a microdispensing pump with high repeatability, and a pump system with two pumps working with an offset to reduce flow irregularities. Furthermore, the fundamental behavior of paraffin as a microactuator material has been explored by finite element modeling. One possibility that arises with high-pressure microfluidics, is the utilization of supercritical fluids for different applications. The unique combination of material properties found in supercritical fluids yields them interesting applications in, e.g., extraction and cleaning. In an attempt to understand the microfluidic behavior of supercritical carbon dioxide, the two-phase flow, with liquid water as the second phase, in a microchannel has been studied and mapped with respect to both flow regime and droplet behavior at a bi-furcating outlet.

Existing actuators in robotics are noisy, rigid and not very lifelike in their movements. There is a need for actuators in especially limb prosthetics and exoskeletons that are silent, softly moving and preferably operating on low currents. One such solution is the conducting polymers. Textiles are well researched and there is a wide variety of patterning. Even more important is their reproducibility and how easily they are mass-produced. This thesis work combines conducting polymers with textiles to achieve linear textile actuators. The textiles are coated with the conducting polymer Polypyrrole which has the property of volume change, when a voltage is applied and there is a reservoir of ions accessible. The volume change, expansion and contraction, results in a linear actuation. The force and strain are measured while changing different parameters and the results are evaluated in this thesis.

Piezoelectric composites have been investigated for use in a variety of areas, including flow control, structural control, energy harvesting, and fuel ignition systems. While many of the investigations conducted in these areas have utilized traditional piezo actuation systems, such as unimorphs or stack actuators, a growing number of research groups are examining the increased performance derived from the mechanical advantage, and enhanced domain rotation, found in prestressed unimorph designs. Prestressed devices, like Thunder® and LIPCA, have been shown well suited for a number of applications; however, the price associated with these devices can often prevent them from being implemented. In an effort to produce a low cost unimorph device that possesses a performance-enhancing curved form, the present investigation presents a novel technique for manufacturing prestressed piezoelectric actuators that are capable of meeting the same high displacement and load bearing capabilities exhibited by conventional prestressed devices. The newly proposed mechanically prestressed composite device, or MPC, is similar in form and function to well-documented thermally prestressed devices like Thunder®. However, rather than deriving its characteristic curved form from a thermally induced stress, the present class of devices relies on the resorting force incited in the piezoelectric ceramic upon adhesion to a mechanically deformed substrate to provide both the performance-enhancing prestress and final form of the device. To aid in refinement of the newly proposed design, beam theory was used to model the stress developed within the device. The model allowed designers to investigate the limitations imposed on the performance-enhancing curved form of the device by the stresses developed in the ceramic as a result of the curvature. Findings derived from the model were experimentally verified before a finalized design was specified for the composite, and a number of devices were manufactured. An initial characterization of the device was carried out based on the composite's response to mechanical and electrical loading. By determining the slope of the electrically and mechanically induced displacement response of the device, the investigation was able to define the center displacement constant and effective spring constant of the unimorph. These parameters not only allow designers to predict the displacement that will occur in response to a given electric field or tensile load, but also to allow for comparison with various devices. In the present investigation, the performance characteristics of mechanically prestressed composites were assessed as a function of substrate thicknesses and adhesive properties. With composites constructed using substrates approximately 9.2cm in length, devices were found to have typical center displacement constants on the order of 1.59 to 7.78kV/mm2 while retaining an effective stiffness between 4.5 to 7.5N/mm. These values were found to be similar to the .71 to 3.85kV/mm2 center displacement constants demonstrated by similarly sized and shaped Thunder® devices, which posses an effective stiffness in the range of 10 to 16.3N/mm. A comprehensive presentation of the test methods and procedures used to determine these values, along with other performance characteristics, are provided.

Ces travaux de thèse s’intéressent à la conception et à la mise en forme d’actionneurs à base de polymères conducteurs électroniques dans l’optique d’un actionnement linéaire à l’air pour une application spatiale. Actuellement, et alors que certaines problématiques récurrentes de légèreté, de flexibilité et de robustesse peuvent être résolues par ces actionneurs, des limitations restreignent encore leurs utilisations dans un environnement spatial pour une déformation linéaire.En premier lieu, nos matériaux composés de réseaux interpénétrés de polymères (RIP) poly (oxyde d’éthylène) (PEO), caoutchouc nitrile (NBR) et de polymère conducteur électronique (PCE) (poly (3,4-éthylènedioxythiophène)) (PEDOT) sont décrits et les différentes caractérisations mécaniques, microscopiques et électrochimiques traditionnelles sont expliquées. Des caractérisations plus spécifiques à un actionnement linéaire ont également été développées.Une étude sur la compatibilité d’actionneurs à base de RIP NBR/PEO et de PEDOT avec un environnement spatial a été réalisée en partenariat avec le CNES. Les conditions auxquelles les échantillons ont été exposés pour simuler un environnement spatial sont des variations de températures importantes, un vide poussé et des radiations gamma. Cette étude a été réalisée sur des actionneurs classiques dont la synthèse et les méthodes de caractérisation sont maîtrisées.Par la suite, nous nous sommes intéressé à la conception d’un actionneur basé sur les mêmes composants qu’un actionneur classique mais permettant une déformation linéaire. Pour cela, un modèle électromécanique a été élaboré en collaboration avec le Pr J. Madden (Vancouver, Canada). Ce modèle permet de déterminer une géométrie adaptée à un actionnement linéaire et d’en optimiser les performances. Un prototype d’actionneur linéaire a donc été synthétisé sur la base de ce modèle.Enfin, la dernière partie a été dédiée à une amélioration des performances de l’actionneur en modifiant la voie de synthèse du PCE. L’électropolymérisation permet en effet de contrôler le type de PCE déposé, sa morphologie ou encore sa quantité. Différents actionneurs à géométrie classique ont alors été réalisés avec du PEDOT électrochimique puis caractérisés. Ces actionneurs ont ensuite été considéré comme candidat potentiel pour constituer une ou plusieurs électrodes de l’actionneur linéaire. / This PhD work deals with the conception and shaping of actuators based on electronic conductive polymers for a linear actuation in open air with an application in space field. Currently, while some recurrent problems of lightness, flexibility and robustness can be resolved by these actuators, limitations still restrict their use in a spatial field providing a linear motion.First, our materials composed of interpenetrating polymer networks (IPN) poly (ethylene oxide) (PEO), nitrile butadiene rubber (NBR) and electronically conductive polymer (ECP) (poly (3,4-ethylenedioxythiophene)) (PEDOT) are described and several mechanical, microscopic and electrochemical characterizations are explained. More particular characterizations have been developed for linear actuators.A study about PEO/NBR/PEDOT based actuator compatibility with space environment have been carried out in partnership with CNES. Samples have been exposed to high temperature variations, a strong vacuum, and gamma radiations to simulate space conditions. This study has been carried out on usual actuator, whose synthesis and characterization technics are mastered.Afterward, the conception of an actuator based on the same compounds as a usual actuator but with linear motion has been studied. To do so, an electromechanical model has been developed with the collaboration of Pr. J. Madden (Vancouver, Canada). This model allows us to determine an adapted geometry for linear motion and to optimize the actuator’s performances. Thus, a prototype of linear actuator has been synthesized based on this model.The last part was dedicated to the improvement of the actuator performances by changing the synthesis of the ECP. Electropolymerization allows us to control what type of ECP is deposited, the morphology or the amount. Several actuators with a usual geometry have been synthesized with electrochemical PEDOT and then they have been characterized. Afterward, those actuators have been used in the model to be part of the potential candidate for the making of a linear actuator.