With the rapid progress of nanotechnologies, there are two developing trends for the next generation of sensors: miniaturization and multi-functionality. Device miniaturization requires less power consumption, or even self-powered system. Multi-functional devices are usually based on multi-property coupling effects. Piezoelectric semiconductors have been considered to be potential candidates for self-powered/multi-functional devices due to their piezotronic coupling effect. In this dissertation, ZnO and CdSe nanowire arrays have been synthesized as the piezoelectric semiconductor materials to develop the following self-powered/multi-functional sensors: (1) self-powered gas sensors of ZnO/SnO2, ZnO/In2O3, ZnO/WO3 and CdSe nanowire arrays have been assembled. All these gas sensors are capable of detecting oxidizing gas and reducing gas without any external power supply owing to piezotronic effect which can convert mechanical energies to electrical energy to power the sensors; (2) a self-powered ZnO/ZnSe core/shell nanowire array photodetector has been fabricated. This photodetector is able to detect the entire range of the visible spectrum as well as UV light because of its type II heterostructure. The absolute sensitivity and the percentage change in responsivity of the photodetector were significantly enhanced resulting from the piezo-phototronic effect. The photodetector also exhibited self-powered photodetection behavior; (3) three dimensional nanowire arrays, such as ZnO and ZnO/Co3O4, have been synthesized to investigate piezo-magnetotronic and piezo-photo-magnetotronic effects. Under magnetic field, the magnetic-induced current of ZnO nanowire array decreased as magnetic field increased, and the current difference was magnified by one order of magnitude caused by piezo-magnetotronic effect through applying a stress. In contrast, under UV light illumination, the current response increased with an increment of magnetic field. The current difference was enhanced by at least two orders of magnitude attributed to piezo-photo-magnetotronic effect. Furthermore, ZnO/Co3O4 core/shell structure was employed to further improve the magnetic-induced current difference. This phenomenon projects a potential for multi-functional piezo-magnetotronic and piezo-photo-magnetotronic device development.

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Among the MEMS field, the design and simulation of piezoelectric micro-actuators are difficult as compared to thermal micro-actuators and electrostatic micro-actuators. The main reason of the piezo-electric material coupling effect is difficult to calculate. However the piezo-electric material has several advantages and characteristics for designing micro-actuators. Moreover, the design is usually done by the experimental or try-and-error method which is not so effective. It should be noted that there is not a simple method already developed for the design and simulation of the piezo-electric micro-actuators. In this research we proposed to use the software of ANSYS for the simulation of piezo-electric micro-pump. Simulation of force output of piezo-micro-pump can use ANSYS software to establish the simulation system of piezo-micro-pump. The micro-pump will have different resonance frequency, back-pressure and fluid due to piezo-electric characteristic. In this study, the author used a square, rectangle and circle geometric shape to simulate the result, each geometric shape has four different kinds of size. As a result, there are twelve groups of different simulation results. We are able to using the chart to present and explain the relation between resonance frequency and displacement.

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Piezoelectric and high speed rotary instrumentation have proven to be viable methods of preparing osteotomies during lateral sinus wall surgery. Piezoelectric units have been suggested to have superior access and control as well as the ability to discern between soft and hard tissue. The major disadvantage of the piezoelectric technology is the reduced speed at which osteotomies are prepared. The purpose of this study was to evaluate the difference in operator perception, speed and membrane damage between the two modalities. Seven different operators prepared 4 osteotomies in 2 mm thick polyurethane sheets backed by 0.2 mm thick plastic wrap. The preparation speed and incidence of membrane damage were recorded after each osteotomy. The operator perception of each modality was recorded at the end of the preparations. Several questions were asked to evaluate the accuracy, visibility, vibration, comfort and ease of use of both modalities. Results showed that rotary instrumentation was 160% faster than piezo (p<0.001), but resulted in 370% more damage and 130% more perforations (p<0.01). Surveys of operator preference showed piezo units with higher scores for accuracy and visibility (p<0.05). This study showed that in vitro a piezo unit compared to a rotary unit results in less membrane perforation and damage, higher perception of accuracy and visibility, but longer osteotomy preparation time. / Oral Biology

Piezoelectric actuation is an expanding field that makes use of piezoelectric materials that have high power density as actuators. These actuation systems have the potential higher power density than the traditional servo motor technology. However, due to tiny strain of the piezoelectric materials, displacement amplification mechanism should be incorporated into design for most commercial applications. Piezohydraulic actuation provides an ideal amplification that can achieve any combination of stroke and force, which is superior than most other amplification technologies. The concept of piezohydraulic actuation takes advantage of the high force capabilities that piezoceramics have and combines it with the operation at high frequencies, in order to achieve the hydraulic actuation of a system under a specified stroke and force. In this research, a compact piezohydraulic pump with active valves has been developed, tested and characterized. Furthermore, theoretical models are developed based on different levels of approximation of the hydraulic fluid. The first model, which assumes an incompressible and inviscid fluid, provides us views of the basic features of piezohydraulic actuation. The second model which takes into account the viscosity of the fluid and the third model which takes into account both viscosity and compressibility of the fluid are then presented. Then, their simulation results are compared with experimental data, which shows the compressibility of the fluid is important to system performance. At last, a power and efficiency analysis based on experimental results is presented. / Master of Science

Piezotronic and piezo-phototronic is a burgeoning field of study which emerges from the coupling of intrinsic materials properties exhibited by non-centrosymmetric semiconductors. In the past decade research efforts were mainly focused on the wurtzite family of 1D nanostructures, with major emphasis on ZnO nanowire nanogenerators, MS piezotronic transistors, LEDs and photodetectors mainly integrated on single nanowires. In view of previously known advantages of charge carrier separation in radial heterojunctions, particularly in type-II core/shell nanowires, it can be anticipated that the performance of photosensing devices can be largely enhanced by piezo-phototronic effect. Moreover, the performance metrics can be further improved in an array of nanowires where geometrical feature enabled multiple reflection can efficiently trap incident illumination. The crux of this dissertation lies in the development of 3D type-II core/shell nanowire array based piezo-phototronic device and also to investigate the effect of magnetic field on ZnO nanowire arrays based piezotronic and piezo-phototronic device for new class of sensors. In this regard, prototype piezo-phototronic broadband photodetectors integrated on two material systems, namely type-II CdSe/ZnTe 3D core/shell nanowire arrays and fully wide band gap type-II ZnO/ZnS 3D core/shell nanowire arrays have been developed where the photodetection performance of each device exhibits high sensitivity, fast response and large responsivity. The application of piezo-phototronic effect further improves the device performance by three to four orders of magnitude change numerically calculated from absolute responsivities at multiple wavelengths. A 3D ZnO nanowire array based new class of piezo-photo-magnetotronic sensor is also developed for detection of pressure, illumination and magnetic field suggesting multiple functionality of a single device where more than one effect can be coupled together to exhibit piezo-magnetotronic or piezo-photo-magnetotronic type of device behavior.

Les matériaux magnéto-électro-élastiques (MEE) sont l'association des matériaux piézo-électrique et piézo-magnétique qui présentent un couplage "magnéto-électrique". L'objectif de cette thèse est d'étudier d'une part, le comportement effectif de ces composites et d'autre part, la propagation des ondes planes dans le milieu homogène équivalent. Dans la première partie de la thèse, nous avons modélisé le comportement effectif des composites MEE à partir de la méthode de la moyenne. Nous avons d'abord établi les équations générales, ensuite nous avons traité le cas où chaque phase est supposée isotrope transverse suivant un axe et polarisée suivant la même direction. La loi de comportement obtenue, ainsi que les tenseurs effectifs du milieu homogène équivalent ont été établis. Les propriétés élastiques effectives sont influencées par les propriétés électriques et magnétiques et réciproquement. Nous nous sommes intéressés en particulier à deux types de composites : les stratifiés et les fibres longues. L'influence de la géométrie des constituants ainsi que la proportion des phases sur le comportement effectif ont été étudiées. La deuxième partie du travail a porté sur l'étude de la propagation d'ondes planes dans les stratifiés. En utilisant la méthode d'homogénéisation périodique, nous avons obtenu les équations de la dynamique dans le milieu homogène équivalent. La longueur d'onde considérée est supposée grande devant la périodicité spatiale. Une méthode de résolution numérique a été développée afin d'obtenir les courbes de dispersion. Nous avons obtenu ces courbes en fonction des proportions des phases constitutives. Bien que les trois propriétés: élastique, électrique, magnétique, contribuent au comportement oscillatoire global, l'onde conserve essentiellement une nature élastique. / The objective of this thesis is estimating fundamental properties and studying the propagation of waves in the equivalent homogeneous medium based on the periodic magneto-electro-elastic (MEE) composite. These artificial MEE media are realized by means of combining piezo-electric and piezo-magnetic materials, and featurea direct "magneto-electric" coupling. In the first part, we modeled the effective behavior of these composites applying the averaging method. First, we derived the general equations, then we treated a particular case a uni axial medium comprised of alternating layers of piezo-electric and piezo-magnetic phases and polarized in the direction normal to the surfaces of these layers. The law of behavior was obtained as well as the effective tensors of the equivalent homogeneous medium. The effective elastic properties are influenced by the magnetic and electrical properties and inversely. We were particularly interested in two types of materials: multi-layers (planar symmetry) and long fibers (cylindrical symmetry). The influence of the geometry of these components on the effective behavior was revealed. The second part of the study focuses on the propagation of plane waves in the case of periodic multilayer structures. Using the periodic homogenization method, we obtained the effective tensors and the equations of propagation of elasto-electro-magnetic plane waves. The wavelength is supposed much larger than the spatial period of the investigated structure, hence the quasi-static approximation for the equations of electromagnetic could be used. The chosen method has allowed estimation of the wave frequency as a function of the wave number, the corresponding dispersion curves were plotted for a wide range of proportions of the constituent materials. Although all the three properties, mechanical, electrical and magnetic contribute to the global oscillatory behavior, the wave is essentially elastic.

Combustion-engine control is one of the most important parts of engine application and has a direct impact on its characteristics. Diploma thesis shows the preparation of a test engine and its installation to test cell. It describes measurement and data post processing necessary for common-rail diesel engine control and their application in the creation of a mathematic model in GT-SUITE.

This bachelor thesis in Mechatronics account for the process of constructing an automatic guitar tuner by means of a piezo-electric sensor, a stepper motor and Arduinobased control. The E4 - string on an acoustic guitar was used as a proxy for tuning any other possible guitar string. The accuracy and tuning-speed of the construction was examined through physical experimentation. Accuracy was measured in terms of the average distance from a piezo calibrated frequency value. The tuning-speed was appraisedby counting the number of times a guitar string had to be plucked before the motor stopped within an acceptable tuning interval. The automatic guitar tuner were able to reliably get the E4 - string in tune by plucking it once within an interval of ±2 Hz and +3.8 cents and −5.1 cents from the theoretical value. The average error was −3.4 cents from the targeted value. / I följande kandidatexamensarbete kontrueras en automatisk gitarrstämmare med hjälp av en piezosensor, en stegmotor och en Arduino-mikrokontroller. E4-strängen på en akustisk gitarr användes som substitut för hur stämningsproceduren skulle kunna fungera för vilken annan gitarrsträng som helst. Noggrannheten samt stämningshastigheten undersöktes genom experiment. Genomsnittet av frekvensskillnaderna mellan de piezo-kalibrerade avläsningsvärdena och E4-strängens värden definierade måttet på noggrannhet. Hastigheten på strängstämningen beräknades i form av hur många gånger en sträng behövdes slås an innan strängen var inom ett godkänt intervall. Den automatiska gitarrstämmaren visade sig pålitiligt kunna stämma E4-strängen på ett försök inom ett noggrannhetsintervall på ±2Hz från det teoretiska värdet. Stämmaren kunde stämma inom +3.4 cents och−5.1 cents samt var var i genomsnitt −3.4 cents i från det teoretiska värdet.