Bimorph

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

Mechanically and electrically nonlinear non-ideal piezoelectric energy harvesting framework with experimental validations

Abstract: In the literature of vibration energy harvesting, mechanically nonlinear frameworks have mostly employed linear electrical circuitry to formulate AC input–AC output problems, while the existing efforts on nonlinear power conditioning circuits have assumed linear mechanical behavior. However, even for the simplest case of a stiff (geometrically linear) piezoelectric cantilever, material softening and dissipative nonlinearities in the mechanical domain have to be accomodated to accurately predict the response for moderate to high excitation levels, and likewise a stable DC signal must be obtained to charge a storage component in realistic energy harvesting applications. Furthermore, often times the voltage output is not large enough to assume ideal diode behavior to reduce diodes to switches in AC–DC conversion modeling. Therefore, a relatively complete representation of piezoelectric energy harvesting requires accounting for the mechanical (e.g., material and dissipative) nonlinearities as well as the nonlinear process of AC–DC conversion with non-ideal circuit elements, such as real diodes. To this end, we present and experimentally validate a multiphysics framework and harmonic balance analysis that combines these mechanical and electrical nonlinear non-ideal effects to predict the DC electrical output (DC voltage across the load) in terms of the AC mechanical input (base vibration) for arbitrary vibration and voltage levels. The focus is placed on a bimorph cantilever with piezoelectric laminates under base excitation. The terminals of the piezoelectric layers are combined in series and connected to a bridge rectifier with non-ideal diodes and a filter capacitor. The multi-term harmonic balance framework can capture the ripple in the DC signal as well as amplitude-dependent nonlinear dynamics accounting for realistic diode behavior. In addition to quantitative comparisons and validations by comparing the experimental data and model simulations, important qualitative trends are unveiled for mechanically and electrically nonlinear non-ideal dynamics of piezoelectric energy harvesting.

Method and system for measuring physical parameters with a piezoelectric bimorph cantilever in a gaseous or liquid environment

Abstract: A piezoelectric bimorph cantilever is used for determining physical parameters in a gaseous or liquid environment. The sensor works as a driven and damped oscillator. Contrary to common cantilever sensor systems, the piezoelectric film of the bimorph cantilever acts as both a sensor and an actuator. Using at least two resonance mode of the bimorph cantilever, at least two physical parameters can be measured simultaneously in a gas or a liquid. An optimized piezoelectric cantilever and a method to produce the cantilever are also described.

Sensor Property of a Novel EAP Device with Ionic-liquid-based Bucky Gel

Abstract: Bucky gel actuator is a novel electro-active polymer (EAP), which is a low-voltage driven dry soft actuator. Its device has a bimorph structure with polymer-supported bucky gel electrodes and a polymer-supported ionic gel electrolyte. It can be fabricated by layer-by-layer casting, to form any shape easily. Some of the EAP materials can be used as a sensor as well as an actuator. If sensor function and actuator function exist in a same device, both function can be integrated with keeping the advantages of functional polymeric material. Miniature actuator-sensor systems and feedback control systems can be constructed; therefore, possibility of application can be expanded. In this paper, we verify the sensor device property of bucky gel devices. Based on the experiment, the relationship between an output signal and a deformation is investigated, and an estimation method of a deformation is demonstrated.

Harvesting the Ultimate Electrical Power From MEMS Piezoelectric Vibration Energy Harvesters: An Optimization Approach

Abstract: Optimized MEMS piezoelectric vibration energy harvesters with maximum possible power generation have been proposed. The energy harvesters work based on the transduction of the applied vibration induced stress on the cantilever beams into the electrical power. Particle swarm optimization approach has been used to design the optimum unimorph and bimorph structures. The optimization has been done for different combinations of the top and bottom piezoelectric layers in bimorph energy harvesters. The geometries of the proposed structures and their harvested powers before and after the optimization have been calculated and compared. The optimization parameters have been chosen so that asymmetric structures with partial coverage of piezoelectric layers would be investigated. The results show that the proposed structures serve as the maximum power generators and provide the largest possible electrical power. In order to limit the beam free end displacement, a guided two beam design has been proposed and optimized. The proposed bimorph guided two beam energy harvester could achieve the minimum displacement which has a key effect on the lifetime of the energy harvesters.

Energy harvesting using piezoelectric materials in aerospace structures

Abstract: Piezoelectric energy harvesters (PEHs) are piezoelectric architectures that are smartly designed to maximum capture ambient vibration/motion energy into piezoelectric material and convert the mechanical energy into electrical energy. The critical piezoelectric material properties for energy harvesting are briefly introduced to provide the reader with a basic background. The state-of-the-art piezoelectric energy harvesting technologies have been reviewed. These PEH concepts include the cantilever beam-based unimorph and bimorph PEHs, flextensional PEHs, edge-clamped PEHs, and the advanced PEHs. Flextensional PEHs are the most promising PEH technology on the market because their average power output is at least one order of magnitude higher than cantilever beam PEHs and edge-clamped PEHs. Flextensional PEHs are also relatively easily integrated into aerospace space systems with little effect on flow dynamic control. In addition, flextensional PEHs can be operated in both resonance and off-resonance modes. Cymbal-type flextensional PEH research opened the door to flextensional PEHs. The “33” mode multilayer stack-based flextensional PEH is one of the most promising PEHs for practical application, with advantages such as capturing more mechanical energy into the piezoelectric structure, increasing mechanical to electrical energy conversion efficiency three to fivetimes, and increasing energy storage efficiency with optimized multilayer configuration. The electrical power delivery from a piezoelectric structure to a resistive load and the energy storage issues are addressed. PEH characterization methods are briefly introduced. Finally, suggestions on PEHs for aerospace applications are discussed.