Investigation of dynamics of microelectromechanical systems (MEMS) is an important problem from the point view of engineering, technology and metrology. Due to high surface to volume ratio of micro-electromechanical systems (MEMS), more attention must be paid to control their surface characteristics. Time average optical holography - has found many industrial applications and still is a promising method (like others: laser interferometry in small object displacement analysis.) This technique can reveal the shape, direction, and magnitude of the stress induced displacement in the structure under study. In this way, time average holography is a powerful tool for analysis of micro scale vibrations. The threshold of sensitivity of this measurement technique is defined by the magnitude of the wavelength of the illuminating laser beam. Also, this is a full field non-destructive technique capable to register the motion of the whole surface instead of a single point. The time average holography method is proposed to control kinetics of oscillations of the micro scale object, operating at the different amplitudes of periodical excitation. Theoretical calculations as well as experimental verification are described.
A cantilever-type electrostatically actuated microelectromechanical (MEMS) switch and its fabrication technology have been developed for the first time in Lithuania, in Kaunas University of Technology. The microdevices were fabricated using nickel surface micromachining technology on substrates made of semiconductor (silicon) and insulator materials (quarts and ceramics). The microswitch consists of cantilevered nickel structure suspended over actuation and contact electrodes. The width of the cantilever contacting element is 30 μm, thickness is about 2.0 μm and length ranges from 67 to 150 μm. Implementation of microswitches as a substitute for present switching devices poses many problems. In particular lower switching speed and reduced lifetime are considered to be among the most significant ones. These characteristics are determined both by design and dynamic phenomena that are taking place during its operation. Specifically, when the microswitch closes, it bounces several times before making permanent contact. These impact interactions greatly influence microswitch durability and switching speed. With the aim of improving these parameters a comprehensive finite element model is being developed that takes into account not only electrostatic actuation and squeeze-film damping effects but also describes important dynamic phenomena - impact interactions that take place during switching. Experimental research of electrical and dynamic characteristics is also carried out with the purpose of device model validation and correction. The paper presents design and fabrication process of the developed microswitch as well as initial simulation and measurement results.