Bimorph

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

An integrated electrochemical sensor–actuator system

Abstract: The use of bimorph actuators based on conducting polymers (CP) in an integrated oxygen control system is explored with practical focus on the control of a fruit storage atmosphere at 5% oxygen. A low-cost oxygen sensor is integrated with a simple actuator valve to limit the influx of atmospheric oxygen to the storage package. For this task, electrochemical oxygen sensors as used in the study, such as zinc–air cells with output potentials up to 1 V, appear to be well suited to drive trilayer strips based on CPs that actuate over a similar range. The actuator used, based on polypyrrole (Ppy), gave reliable and repeatable mechanical behaviour for about 50 h. Two sensor–actuator systems have been trialled. In one, the output from a lead-oxygen sensor was electronically augmented to drive a conducting polymer trilayer actuator valve. The desired oxygen concentration was easily maintained with response times of tens of seconds. The other system used the output from a zinc–air cell directly to drive an actuator valve that limited the diffusion of air into the enclosure. Positive oxygen concentration control was achieved but at lower rates of oxygen flux and longer response times. Good sealing of the orifice at closure was found to be critical.

Particle swarm approach to the optimisation of trenched cantilever-based MEMS piezoelectric energy harvesters

Abstract: A micro-electro-mechanical system (MEMS) trenched piezoelectric energy harvester based on a cantilever structure has been proposed. The trenched piezoelectric layer has increased the output voltage and the generated power. It also provides three additional design parameters such as the trench position, depth and length. A particle swarm approach has been used for optimisation of the piezoelectric energy harvester geometry with the aim of finding the optimum design which transfers the maximum harvested power to a definite load. The optimisations and comparisons have been made for unimorph, bimorph, trenched and non-trenched cantilever beams. The results are quite revealing that the generated power for a trenched bimorph energy harvester is much larger than other structures. The optimum design found by particle swarm optimisation algorithm has asymmetric trenches in the top and bottom piezoelectric layers and can generate much more power than the unoptimised structure.

Thin-film piezoelectric bimorph actuators with increased thickness using double Pb[Zr,Ti]O3 layers

Abstract: We studied the effects of increasing the thickness of bimorph structures containing double layers of Pb(Zr,Ti)O3 (PZT) thin films. Thick PZT films allow high-voltage application (e.g. in terms of coercive electric field and breakdown voltage) and large generative force, which are effective in microelectromechanical systems (MEMS) applications. Improvement of the deposition conditions and electrode structures facilitates the fabrication of the thin-film PZT/PZT bimorph structure. The PZT/PZT bimorph with a total thickness of 5.8 µm, deposited using a radio-frequency (RF) magnetron sputtering system is much thicker than conventional bimorph structures. The characteristics of the two piezoelectric layers were similar to each other and revealed good electric and ferroelectric characteristics with a remanent polarization of 20 µC cm−2 and a coercive electric field of 50 kV cm−1. PZT/PZT bimorph cantilevers were fabricated in order to evaluate their characteristics for actuator applications. The residual stress of the bimorph cantilever was reduced by an annealing process. The vibration test on the fabricated bimorph cantilevers during electrical voltage application revealed a twice as large displacement as compared with a single layer actuation, and the piezoelectric coefficient value d31 was estimated to be −61 pm V−1, which is better than the value of conventional PZT/PZT bimorph cantilevers (−13 pm V−1). It was also shown that the influence of the temperature change is much less than that in unimorph structures with similar dimensions. The evaluated results demonstrate that the PZT/PZT bimorph structures are effective as MEMS devices.

Characterization and evaluation of piezoelectric composite bimorphs for in‐situ acoustic emission sensors

Abstract: Mixed connectivity composites consisting of a ferroelectric ceramic powder of calcium modified lead titanate dispersed in a polymer matrix have been fabricated into piezoelectric bimorph sensors. The piezoelectric, dielectric and electromechanical coupling coefficients of these sensors have been measured and a full characterization of the electromechanical properties are reported. The suitability of these bimorph transducers as in-situ acoustic emission sensors, embedded into glass-epoxy laminate plate like structures, has been investigated. A comparison of the performance of these sensors to those of previously investigated monomorph sensors fabricated from the same material has been made.

Structure design and experimental study on single-bimorph double-acting check-valve piezoelectric pump:

Abstract: A novel piezoelectric pump called single-bimorph double-acting check-valve piezoelectric pump was proposed in this paper in order to improve the output performance of the single-bimorph single-cham...