MEMS Technologies for Energy Harvesting

The objective of this chapter is to introduce the technology of Microelectromechanical Systems, MEMS, and their application to emerging energy harvesting devices. The chapter begins with a general introduction to the most common MEMS fabrication processes. This is followed with a survey of design mechanisms implemented in MEMS energy harvesters to provide nonlinear mechanical actuations. Mechanisms to produce bistable potential will be studied, such as introducing fixed magnets, buckling of beams or using slightly slanted clamped-clamped beams. Other nonlinear mechanisms are studied such as impact energy transfer, or the design of nonlinear springs. Finally, due to their importance in the field of MEMS and their application to energy harvesters, an introduction to actuation using piezoelectric materials is given. Examples of energy harvesters found in the literature using this actuation principle are also presented

K-band RF-MEMS uniplanar reconfigurable-bandwidth bandpass filter using multimodal immittance inverters

A K-band RF-MEMS uniplanar second-order bandpass filter with reconfigurable bandwidth is presented. The filter is based on inductively- coupled half-wavelength slotline resonators and CPW-slotline multimodal immittance inverters (MIIs). The coupling inductance and the MII length are reconfigured using RF-MEMS ohmic-contact switches. Experimental results show a 3 dB relative-bandwidth change from 4.5 to 8.5% (maintaining a Butterworth response), and insertion losses of 5.2 and 3.7 dB for either state

Analytical Energy Model for the Dynamic Behavior of RF MEMS Switches Under Increased Actuation Voltage

In this paper, the dynamic behavior of electrostatically actuated radio frequency-microelectromechanical system (RF-MEMS) switches is analyzed using energy considerations. An analytical model for bridge-type RF-MEMS switches is proposed and the time evolution of the system total energy is calculated numerically. Switch actuation, release times, and damped release response are derived from energy analysis with focus on the effect of increasing the actuation voltage on the RF-MEMS dynamic behavior. The dynamic and RF characteristics of different RFMEMS ohmic-contact switches have been measured using an experimental set-up based on microwave instrumentation. The measured results show a good agreement with simulations, thus validating the proposed analytical model. It is shown (theoretically and experimentally) that the damped release response increases the effective time to reach the RF/microwave OFF-state switch isolation (up to three natural periods of the mechanical system)