Topic
Bimorph
About: Bimorph is a research topic. Over the lifetime, 3339 publications have been published within this topic receiving 51880 citations.
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16 citations
TL;DR: In this article, a detailed analysis is carried out of the resonance frequency of the cantilever as a function of its length, deflection and thickness of the upper electrode layer, including the effect of undercut.
Abstract: A systematic study is presented on the modelling, fabrication and measurements of curled micro-bimorph cantilevers, which are composed of a dielectric beam with a metal electrode layer coated on top. The device, having stress-induced upward curvature in the electrical off-state, functions as a vertical electrostatic actuator for nanometre displacements. A detailed analysis is carried out of the resonance frequency of the cantilever as a function of its length, deflection and thickness of the upper electrode layer, including the effect of undercut. A Galerkin-based static model is used to predict the pull-in voltages which are validated by measurements. A dynamic model is used to investigate the shift in resonance frequency by the electrostatic spring softening effect, which is evaluated against experimental data. The measured shift in resonance frequency is further extrapolated to non-destructively predict the pull-in voltages.
16 citations
TL;DR: Xu et al. as discussed by the authors analyzed the acoustic properties of a bimorph-based piezoelectric air transducer with the working frequency range of 200-1000 Hz.
Abstract: A new type of bimorph-based piezoelectric air transducer with the working frequency range of 200–1000 Hz has recently been developed [B. Xu, Q. Zhang, V.D. Kugel, L.E. Cross, Piezoelectric air transducer for active noise control, Proc. SPIE, 2717 (1996) 388–398]. In the present work, basic acoustic characteristics of this device and its piezoelectric elements are analyzed. To model the vibration spectrum of the transducer, a one-dimensional approach is developed where inertia, elastic and damping forces are included. Analytical equations describing mechanical vibrations and electrical impedance of piezoelectric bimorph cantilevers under external forces are derived. In order to describe various losses in the transducer, complex piezoelectric, dielectric, and elastic constants are used. Results of the modeling are in good accord with experimental data. The suggested model can be used for device optimization.
16 citations
TL;DR: In this paper, a cantilever type bimorph which was formed by laminating two PZT piezoelectric layers was presented, which can scavenge mechanical energy from ambient vibrations and transform it into useful electrical energy.
Abstract: We present the development of a MEMS piezoelectric bimorph generator, a cantilever type bimorph which was formed by laminating two PZT piezoelectric layers. Our bimorph generator can scavenge mechanical energy from ambient vibrations and transform it into useful electrical energy. Two poling configurations of the PZT piezoelectric layers of our bimorph MEMS generator were fabricated and tested. A tip proof mass used for adjusting the resonance frequency was also demonstrated. Experimental results confirm that our device possessed a maximum open-circuit output voltage of 1.91VP-P and a 3.42VP-P for a parallel polarization device and a serial polarization device, respectively with a 2g externally applied vibration. At an optimal resistive load, the maximum output power was 1.548μ–W and 1.778μ–W for a parallel polarization device and a serial polarization device, respectively.
16 citations
TL;DR: A thermodynamic analysis of the composite hydrogel containing an embedding coupled chemistry for light-sensitized catalytic reactions that enables chemo-mechanical actuation of poly(acrylic acid)-based gels is described.
Abstract: We describe a composite hydrogel containing an embedding coupled chemistry for light-sensitized catalytic reactions that enables chemo-mechanical actuation of poly(acrylic acid)-based gels. In these materials, a photosensitizer and catalyst—ruthenium trisbipyridine and iridium dioxide nanoparticles, respectively—are incorporated into the hydrogel where together, with visible light irradiation, they undergo a catalytic water-oxidation reaction that lowers the pH and induces a dissipative/chemically-driven strain change in the gel. To demonstrate the capacity for 3D chemo-mechanical actuation, a layer of non-pH responsive poly(2-hydroxyethyl methacrylate) is added to the photo-active composite gel to create a model bimorph actuator. Triggering and terminating the water-oxidation reaction leads to a programmatic expansion and contraction of the active layer, which induces different modes of biomimetic curling motions in the bimorph actuator in light and dark environments. The efficiency of this system is fundamentally limited by the system-level design, which provides no capacity to sustain a local pH gradient against diffusive mixing. Even so, if the initial pH of the background solution is reestablished either actively or passively between each reaction cycle, it is possible to realize multiple cycles of reversible actuation. We describe a thermodynamic analysis of this system which identifies specific features mediating efficiency losses and conceptual requirements for mesoscopic design rules for optimization of this system and for advancing soft actuation systems in general.
16 citations