Bimorph

About: Bimorph is a research topic. Over the lifetime, 3339 publications have been published within this topic receiving 51880 citations.

Electrode Coverage Optimization for Piezoelectric Energy Harvesting from Tip Excitation.

Abstract: Piezoelectric energy harvesting using cantilever-type structures has been extensively investigated due to its potential application in providing power supplies for wireless sensor networks, but the low output power has been a bottleneck for its further commercialization. To improve the power conversion capability, a piezoelectric beam with different electrode coverage ratios is studied theoretically and experimentally in this paper. A distributed-parameter theoretical model is established for a bimorph piezoelectric beam with the consideration of the electrode coverage area. The impact of the electrode coverage on the capacitance, the output power and the optimal load resistance are analyzed, showing that the piezoelectric beam has the best performance with an electrode coverage of 66.1%. An experimental study was then carried out to validate the theoretical results using a piezoelectric beam fabricated with segmented electrodes. The experimental results fit well with the theoretical model. A 12% improvement on the Root-Mean-Square (RMS) output power was achieved with the optimized electrode converge ratio (66.1%). This work provides a simple approach to utilizing piezoelectric beams in a more efficient way.

Dynamic Characteristics of Rainbow Ceramics

Abstract: The piezoelectric resonance behavior of end-clamped bimorph structures made from the rainbow monolithic ceramic have been evaluated. Thickness, width, width flexure, and length bending modes have been identified and measured. Using a very crude model in which the cermet component of the rainbow is assumed to have the same density × elasticity product as the bulk, surprisingly good agreement is obtained between observed and calculated frequency behavior. By appropriate processing it is possible to delaminate the bimorph, and work is now in progress to measure the properties of the two separate phases so that a proper composite resonator model may be developed.

Design and fabrication of twisting-type thermal actuation mechanism for micromirrors

Abstract: This paper reports the design and fabrication of a novel micromirror actuation system. The actuating mechanism for driving the micromirror combines two paralleled bimorph actuators bending in opposite directions for rotational control of the micromirror. Each actuator is structured by nickel and silicon nitride thin-films. Based on thermal and structural analyses, the geometry of the actuation system is optimized to achieve larger tilting angles of micromirrors whose sizes are of the order of 100 × 100 μm2. Operation of the actuation system shows total vertical displacements about 90 μm and tilting angles about 28° for micromirrors of 150 × 150 μm2 in size at input powers about 170 mW and about 60 μm and about 20° for micromirrors of 80 × 80 μm2 in size at input powers about 60 mW, which agree well with predictions from theoretical models and simulations using a commercial code.

Electrothermal actuation studies on silicon carbide resonators

Abstract: The electromechanical behavior of SiC clamped-clamped beam (bridge) resonators with u-shaped aluminium (Al) electrodes on top has been studied as a function of electrode length, width, and spacing Negative and positive deflections have been observed, indicating a complex interplay exhibited by the combined single material and bimorph characteristics of the resonator structures It has been found that, both experimentally and theoretically, devices with electrodes applied on the root of the beam have similar or higher displacement amplitudes compared to devices with electrodes covering the half or the entire beam Moreover, the displacement and vibration amplitudes can be maximized by increasing the electrode width and/or decreasing the spacing

Magneto-optical recording/reproducing system having an electromagnetic actuator

Abstract: Magneto-optical disk recording and reproducing devices and actuators and distance detectors for use therewith are disclosed. The mageneto-optical disk device comprises, in addition to the usual elements, a bimorph type actuator or an electromagnetic actuator for driving the magnetic head of the magneto-optical disk device. The bimorph actuator has a metallic shim whose width varies with respect to the longitudinal distance inversely porportional to the normal function of the first or the second free natural vibration mode. Alternatively, the bimorph type actuator have a recess formed on a bimorph element to expose a piezoelectric crystal which outputs a voltage corresponding to the acceleration of the vibration of the actuator; the driver circuit of the actuator reduces the driving voltage when the frequency of the voltage generated at the recess comes into the neighborhood of a higher resonance frequency of the actuator. The optical distance detector comprises a light-emitting diode and a pair of photodiodes which detects the amount of light incident thereon after being reflected at a surface of an object the distance to which is measured. The geometric parameters of the photodiodes are selected in such a manner that the output of a first photodiode decreases as the measured distance increases while the output of a second photodiode increases as the measured distance increases. Thus, the normalized differential output of the two photodiodes, from which the measured distance is determined, varies substantially linearly with respect to the measured distance. In preferred forms, the photodetectors have stepped concentric configurations so that small distances can be measured accurately and efficiently.