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Abstract

In this paper, we report the advantage of using AC actuating signal for driving MEMS actuators instead of DC voltages. The study is based upon micro mirror devices used in digital mode for optical switching operation. When the pull-in effect is used, charge injection occurs when the micro mirror is maintained in the deflected position. To avoid this effect, a geometrical solution is to realize grounded landing electrodes which are electro-statically separated from the control electrodes. Another solution is the use of AC signal which eliminates charge injection particularly if a bipolar signal is used. Long term experiments have demonstrated the reliability of such a signal command to avoid injection of electric charges.

Mots-Clés / Keywords

Design and test techniques for MEMS;

Abstract

In this publication we describe the use of thermo-activated PNIPAM nano-material in optical switching devices. In other publications, the PNIPAM is used either as a carrier for crystalline colloidal array selfassemblies or as micro-particles that serve as pigment bags. In this publication we use a simpler-to-fabricate pure PNIPAM solution in a semi-dilute regime. The PNIPAM devices produced are transparent at temperatures below a critical temperature of 32°C and become diffusing above this temperature. We show that at 632nm the transmission through the devices is about 75% in the transparent state while the additional attenuation achieved in the diffusing state is of the order of 38 dB. The experimental fall and rise times obtained are large (about 300ms and 5s respectively) due to the non-optimised thermal addressing scheme. In addition, spectral measurements taken in the infrared spectrum (700-1000nm) demonstrate that the cell response is flat over a large portion of the infrared spectrum in both the transparent and the diffusing states.

Résumé

Les microsystèmes électrostatiques se sont développés depuis une vingtaine dannée et ont constitué un événement marquant du développement technologique. La présentation abordera les travaux effectués en termes de modélisation du micro usinage de volume et en termes de développement technologique relatif au micro usinage de surface. Elle sappuiera également sur des exemples de microsystèmes opto électro mécaniques à vocation applicatives tant dans le domaine des télécommunications que des applications militaires. Les prospectives de recherches aborderont les nouveaux développements relatifs à lintroduction des matériaux polymères dans les technologies silicium tout en restant dans le cadre des applications à loptique.

Abstract

Electrostatic Microsystems have been developed in the 80s and they are a milestone for the technological development. The manuscript will present works done with atomic scale modelling of bulk micromachining in silicon and with technological development of a three layer polysilicon surface micromachining. This last point will be illustrated by realisation of an electrostatic side drive micromotor. Other examples of MEMS dedicated to optical applications will be presented either for telecommunication or military applications. The future of works dealing with introduction of polymers in silicon technologies will be also presented.

Mots-Clés / Keywords

Microsystèmes; Gravure chimique anisotrope; Micro moteur; Electrostatiques; Micromiroirs; Commutateurs; Microtechnologies; Modélisation; Microsystems; Bulk micromachining; Micromotor; Electrostatic; Micromirrors; Optical switching; Modelling;