the netherlands), are experimentally characterized. Their behaviour is compared against simulations performed in anSYS Workbench™, confirming good accuracy of the predictive method. Furthermore, the electromechanical multiphysical behaviour of the Flc eh is also analysed in Workbench, by adding a layer with piezoelectric conversion properties in the simulation. The measured and simulated data reported in this paper confirm that the MeMS converter exhibits multiple resonant modes in the frequency range below 1 khz, where most of the environmental vibration energy is scattered, and extracted power levels of 0.2 μW can be achieved as well, in closed-loop conditions. Further developments of this work are expected to fully prove the high-performance of the Flc concept, and are going to be addressed by the authors of this work in the on-going activities.
We present a comprehensive study on an electrostatically actuated RF-MEMS switch with active thermal recovery capability intended to counteract stiction. On the basis of finite element (FE) simulations a detailed model including all relevant physical effects has been developed to investigate this recovery mechanism. The resulting model enables to reproduce the whole recovery process during a failure situation of the switch, proving its functionality and, thus, identifying and elaborating possible design improvements. The simulated results are confirmed by experimental data obtained from white-light interferometry (VEECO) and laser-Doppler vibrometry (Polytec).
MotivationThe reliability of RF-MEMS switches is one of the most crucial requirements limiting the exploitation of MEMS switches on the RF market. Here, stiction constitutes one of the major problems that cause malfunctioning of these switches. The dominant effects leading to stiction are the welding of contact points in the case of high current densities (micro-welding [1]) and the entrapment of charges within dielectric layers (dielectric charging [2]). In order to repair the malfunction of the switch, a thermal recovery mechanism for an electrostatically actuated ohmic RF -switch has been designed at the Fondazione Bruno Kessler (FBK) in Trento, and is described in detail in [3]. Fig. 1: Microphotograph of the RF-MEMS switch.The microswitch consists of a slotted gold membrane hinged by four suspension beams and is actuated electrostatically by applying a DC voltage between the membrane and the underlying electrode in order to close a RF signal line (see Fig. 1). A resistive meander-shaped micro-heater is implemented below each of the gold anchors, at which the switch membrane is suspended, in order to heat up the device. Due to thermal expansion, the membrane is strained, whereby potential welding points may be broken up by the resulting mechanical forces. At the same time, the evolving temperature rise may accelerate the release of charges accumulated in the dielectric layers, also counteracting the effect of dielectric charging. More information on the switch design, the functionality of the thermal recovery mechanism and previous investigations can be found in [3][4][5].Within this work, we concentrate on the mechanism to counteract stiction due to micro-welding or other adhesive forces at the contact pads. To this end, we developed a detailed FE model of the electro-mechanical structure, which allows us to simulate the recovery process including all relevant mechanical, thermal, electrical, and fluidic effects. Tn section two basic model assumptions are introduced and discussed, which have been applied in order to enable the computation of the electro-thermo mechanically coupled problem describing the recovery mechanism in an efficient but yet accurate manner, and the extraction of unknown model parameters is outlined. The workflow of the simulation procedure is explained in detail in section three and the obtained simulation results are discussed in...
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