Browsing by Subject "Piezoelectric"

Now showing 1 - 3 of 3

Open Access
Barrel-stave flextensional transducer design
(2009) Şahin, Aykut
This thesis describes the design of low frequency, high power capability class-I flextensional, otherwise known as the barrel-stave, flextensional transducer. Piezoelectric ceramic rings are inserted inside the shell. Under an electric drive, ceramic rings vibrate in the thickness mode in the longitudinal axis. The longitudinal vibration of the rings is transmitted to the shell and converted into a flexural motion. Low amplitude displacements on its axis create high total displacement on the shell, acting as a mechanical transformer. Equivalent circuit analysis of transducer is performed in MATLAB and the effects of structural variables on the resonance frequency are investigated. Critical analysis of the transducer is performed using finite element modeling (FEM). Three dimensional transducer structure is modeled in ANSYS, and underwater acoustical performance is investigated. Acoustical analysis is performed by applying a voltage on piezoelectric material both in vacuum and in water for the convex shape barrel-stave transducer. Effects of transducer structural variables, such as transducer dimensions, shell thickness, shell curvature and shell material, on the electrical input impedance, electroacoustical transfer function, resonance frequency and quality factor are investigated. Thermal analysis of designed transducer is performed in finite element analysis. Measured results of the transducer are compared with the theoretical results.
Open Access
Experimental and computational investigation of zinc oxide based surface acoustic wave devices
(2014) Özgöztaşı, Elif
Piezoelectric materials are used in different types of transducers such as microphones, accelerometers, speakers, hydrophones, pressure sensors etc. Compared to traditional bulk piezoelectric crystals, thin film piezoelectric materials are promising to realize integrated devices with CMOS technology. Among thin film materials, zinc oxide (ZnO) is attractive due to the giant piezoelectric effect when doped with vanadium. In this study, we investigate the deposition of thin film ZnO and V-doped ZnO films. Materials characterization of ZnO thin films is performed. We also investigate surface acoustic wave (SAW) devices based on ZnO thin films. SAW devices are formed by a pair of interdigitated transducers (IDTs), input and output IDTs. IDTs are fabricated onto the piezoelectric thin film. Applied oscillating electric field from input IDT creates surface acoustic waves in the piezoelectric thin film and these acoustic waves are converted back into an electrical signal at the output IDT. SAW devices based on ZnO and V-doped ZnO films were designed and fabricated. Frequency response of SAW devices is measured. In addition, finite element simulations of SAW devices are shown to be in agreement with measurement results. We discuss resonance frequency and insertion loss of SAW devices.
Embargo
Scalable fabrication of nanomaterial integrated polymer fibers as self-powered sensors
(2023-12) Hasan, Md Mehdi
Wearable electronics have great potential to revolutionize healthcare by enabling real-time data acquisition and transfer. Textiles, a ubiquitous part of our daily lives, get exposed to a vast amount of biomarkers to provide information on health status and the onset of diseases without compromising comfort. Self-powered sensors have gained interest as these devices do not require any external power to operate but rather can harvest energy to operate the low-power elec-tronics. However, textile-based sensor fabrication requires complex multi-step fabrication protocols. In this study, a one-step fabrication of functional fibers for self-powered sensing using thermal drawing process was investigated. Inte-gration of 2D nanomaterials have significantly improved the performance of the fluoropolymer (PVDF) based triboelectric and piezoelectric fibers. 2D nanoma-terials enhance the output predominantly by the combined effect of interfacial polarization and microcapacitor formation. MXene-PVDF nanocomposite fiber shows β phase increases consistently up to 44% upon 5 wt% MXene addition. The triboelectric fiber demonstrates the capability to harvest energy and biomotion monitoring such as gait analysis. The structural design of MoS2-PVDF piezoelec-tric fiber ensures efficient stress transfer to the piezoelectric domain. Moreover, MoS2 addition increases up to 3 wt% with β phase amount 50% and decreases upon higher MoS2 addition. The Piezoelectric fiber demonstrates the ability to detect physiological signals such as pulse and respiration. The sensors can wirelessly transmit data to store and analyze using a microcontroller unit. The demonstration of large-scale fabrication of the self-powered fiber sensors shows the prospect of the technology as industrially translatable for developing smart clothing.