Smart Piezoelectric Thin Layer Transducers for Biomimetic/Biomedical applications
Banihani, Muath Ahmad
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This dissertation discusses models for novel applications of piezoelectric thin films Materials that exhibits the Piezoelectricity direct and converse effects are utilized in this work for both biomimetic and biomedical applications. These materials are called piezoelectric materials. The converse effect is described by the ability of converting an applied electrical potential into mechanical strain. The direct piezoelectric is described by the ability of some materials to transform mechanical strain into a voltage output. Both effects are employed in this dissertation for both actuation and energy harvesting purposes. We use smart actuators to generate traveling wave for biomimetic underwater robot’s purposes. We optimize the third mode shape of the swimmer to generate a waveform that most closely resembles the body waveform of an eel. Smart actuators are good alternative actuators for underwater robots due to their ability to perform flexible and complex movements without additional parts. This provides less noisy and high-performance operation. The theoretical analysis is based on the distributed parameter model. A scalar measure of the traveling to standing wave ratio is introduced using 2-dimensional Fourier Transform. The analytical models are verified by the close agreement between the traveling waves predicted by the model and those measured in the experiments. Furthermore, and in the sense of the piezoelectricity converse effect, a biocompatible dental device/actuator is proposed to generate vibration and thus cyclic forces with specific amplitudes and frequency to accelerate the tooth movement and bone remodeling during the orthodontic treatment. The application of cyclic loading (vibration) reverses bone loss, stimulates bone mass, induce cranial growth, and accelerate tooth movement. This reduces the pain experience and discomfort accompanied by the treatment and also enhance the patient compliance with the treatment. Vibration has the advantage of minimal side effects in comparison to medicinal treatments. The biocompatible actuator is theoretically analyzed and ANSYS finite element analysis (FEA) software is used to realize the piezoelectric actuation behavior. Finally, we discuss the piezoelectric direct effect for energy harvesting purposes. Energy harvesting implies converting the mechanical strain to electrical energy and this is utilized in this dissertation by in proposing a biocompatible dental energy harvester that harvests the energy from the mastication forces. A piezoelectric vibration energy harvester is designed and modeled for this purpose which includes: a 1) monolithic piezoelectric energy harvester and 2) a piezoelectric bimorph buckling beam which is integrated/embedded in the tooth implant. Due to the small size of the tooth harvester, the fundamental natural frequency of the device is in orders of magnitude higher than the dominant frequency of the vibration of the mastication forces. Therefore, resonance conditions are practically unattainable which reduce the power efficiency of the harvester. Thus, the buckling beam harvester scenario is proposed to overcome the non-resonating behavior of the tooth harvester. Both scenarios of the energy harvesters are analytically modeled. The exact analytical solution of the piezoelectric beam energy harvester with Euler–Bernoulli beam assumptions is presented. The electro-mechanical coupling and the geometric nonlinearities have been included in the model for the piezoelectric beam.