Bimorph

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

Thermal noise cancellation in symmetric magnetoelectric bimorph laminates

Abstract: We have found a symmetric Terfenol-D/Pb(Zr,Ti)03 (PZT) bimorph magnetoelectric (ME) laminate, which operates in a bending mode under an unsymmetrical (U-shaped) magnetic bias. It has a giant ME voltage coefficient of about 70V∕cmOe at resonance. Unlike other symmetric ME laminate structures, the symmetric bimorph structure has the capability to reject thermal noise from a magnetic signal, due to its back-to-back structure. The mechanism for the thermal noise cancellation capability is that the laminate operates in a bending mode (out charges of reverse sign), whereas the thermal noise is contained in a longitudinal mode (out charges have the same sign, allowing cancellation by differential detection).

Improvements in energy harvesting capabilities by using different shapes of piezoelectric bimorphs

Abstract: The small amount of power needed by microelectronic devices opens up the possibility to convert part of the vibration energy present in the environment into electrical energy, using several methods. One such method is to use piezoelectric material as an additional layer in cantilever beams to harvest vibration energy for self-powered sensors. The geometry of a piezoelectric cantilever beam will greatly affect its vibration energy harvesting ability. Tapering and changing the configuration as ways to increase the generated output power of cantilever piezoelectric energy harvesters have gained popularity in recent years. In this work vibration energy harvesting via piezoelectric resonant bimorph cantilevers is studied and new designs for obtaining optimal piezoelectric energy harvesters are suggested. This paper deduces a very precise and simple analytical formula that can be used as a rule of thumb for calculating the resonant frequency of bimorph trapezoidal V-shaped cantilevers using the Rayleigh–Ritz method. This analytical formula is then analyzed using MATLAB as well as finite element methods and validated by ABAQUS simulation. Also, mathematical derivations for the output voltage of bimorph piezoelectric energy harvesters are presented and validated by simulation and experimental results. These formulas provide a new perspective that, among all the bimorph trapezoidal V-shaped cantilever beams with uniform thickness, the bimorph triangular tapered cantilever can lead to the highest resonant frequency and therefore maximum sensitivity, and by increasing the ratio of the trapezoidal bases the sensitivity decreases. Also, the output voltage and strain distribution show that the triangular cantilever has the highest efficiency and power density.

System level design of wireless sensor node powered by piezoelectric vibration energy harvesting

Abstract: This paper proposes a design of wireless sensor node powered by piezoelectric vibration energy harvesting system. A complete system level coupling circuit model is established to predict the performance characteristics. The piezoelectric vibration energy harvester (PVEH) is based on a PZT bimorph cantilever, in which a big proof mass is introduced to decrease resonant frequency and a shell served as a stopper to avoid overload. Lumped parameters of the model are identified by experiments and calculations. Electromechanical analogy model of PVEH is simulated in LTspice software. The power consumption of a temperature WSN is tested and the equivalent load model is simulated. A power management circuit (PMC) with LTC3588-1 is designed for rectifying and regulating output of PVEH. Electrical energy is stored in a capacitor. Finally, a system level coupling model is established. Time domain circuit simulation can provide the detailed parameters about the WSN powered by PVEH such as full charge time and sustainable time of the system. Test curves of capacitor charging and WSN power supply in prototype testification show good consistency with the simulation results in LTspice. An application for temperature WSN powered by PVEH is testified as an example. The method and model proposed in this paper can set up a reference to optimize system parameters for WSN powered by PVEH.

Design and fabrication of bimorph transducer for optimal vibration energy harvesting

Abstract: High energy density piezoelectric composition corresponding to 0.9Pb(Zr0.56Ti0.44)O3-0.1Pb[(Zn0.8/3Ni0.2/3) Nb2/3]O3 + 2 mol% MnO2 (PZTZNN) and 0.8[Pb(Zr0.52Ti0.48) O3]-0.2[Pb(Zn1/3Nb2/3)O3] (PZTPZN) were synthesized by conventional ceramic processing technique using three different sintering profiles. Plates of the sintered samples were used to fabricate the piezoelectric bimorphs with optimized dimensions to exhibit resonance in the loaded condition in the range of ~200 Hz. An analytical model for energy harvesting from bimorph transducer was developed which was confirmed by experimental measurements. The results of this study clearly show that power density of bimorph transducer can be enhanced by increasing the magnitude of product (d · g), where d is the piezoelectric strain constant and g is the piezoelectric voltage constant.