Solving functional reliability issue for an optical electrostatic switch

In this paper, we report the advantage of using AC actuating signal for driving micro electro mechanical systems 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.     

PNIPAM: a thermo-activated nano-material for use in optical devices

In this paper 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 self-assemblies 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 632 nm 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 300 ms and 5 s, respectively) due to the non-optimised thermal addressing scheme. In addition, spectral measurements taken in the infrared spectrum (700–1,000 nm) demonstrate that the cell response is flat over a large portion of the infrared spectrum in both the transparent and the diffusing states.     

Calculation of effective inductances of superconducting devices.Application to the cryogenic current comparator

As a consequence of the “image effect” the inductances of coils and superconducting devices do change. Calculations are performed with the help of commercial software based on the finite element method. The results are applied to the design of an optimum cryogenic current comparator     

A multilevel polymer process for direct encapsulation of fluids in microfluidic systems

This paper describes a polymer manufacturing technique for the realization of sealed liquid tanks with a high filling ratio. It is based on a lithographic process combined with lamination and can be performed on any type of substrate: Si, glass or polymer films. We demonstrated the encapsulation of solvents or inks in multilevel tanks on large surface area (>118 cm²) without any damage of the stored liquid. This micro-fabrication technology proposes a significant breakthrough for micro-fluidic applications. We propose a one step process for the filling and sealing of tanks which are performed simultaneously. Tanks can be integrated at any level in the micro-fluidic system with a perfect filling rate and an excellent tightness.     

Identification of nonlinear dynamic models of electrostatically actuated MEMS

This paper focuses on the identification of nonlinear dynamic models for physical systems such as electrostatically actuated micro-electro-mechanical systems (MEMS). The proposed approach consists in transforming, by means of suitable global operations, the input–output differential model in such a way that the new equivalent formulation is well adapted to the identification problem, thanks to the following properties: first, the linearity with respect to the parameters to be identified is preserved, second, the continuous dependence on noise measurements is restored. Consequently, a simple least-square resolution can be used, in such a way that some of the difficulties classically encountered with identification methods are by-passed. The method is implemented on real measurement data from a physical system.     

Soft mold NanoImprint Lithography: a versatile tool for sub-wavelength grating applications

Microsystem Technologies - Due to its independency to the substrate used, Soft mold NanoImprint Lithography (S-NIL) is a technique of great interest in particular for the fabrication of optical...     

Identification of dynamic nonlinear thermal transfers for precise correction of bias induced by temperature variations

We present a general method for dynamic correction of biases induced by temperature variations. This method is simple to implement and useful when very high precision is required: it indeed allows significant improvements compared to standard static corrections. It is mainly based on a universal dynamic model allowing to describe macroscopic effects of complex underlying thermal phenomena inside the device. Some experimental results related to a MEMS with high precision pull-in voltage are presented in order to highlight the efficiency of the approach.     

Characterization of liquid crystals impregnated micrometric diffraction gratings for an active near-IR light extraction control

Microsystem Technologies - Due to their narrow reflection peak as well as their compact structure, guided mode resonance filters (GMRFs) are attractive for many applications. In this work, we will...     

3-D packaging methodologies for microsystems

Issues associated with the packaging of microsystems in plastic and three-dimensional (3-D) body styles are discussed. The integration of a microsystem incorporating a micromachined silicon membrane pump, into a 3-D plastic encapsulated vertical multichip module package (MCM-V) is described. Finite element techniques are used to analyze the encapsulation stress in the structure of the package. Cracks develop in the chip carrier due to thermomechanical stress. Based on the results of a finite element design study, the structures of the chip carriers are modified to reduce their risk of cracking. Alternative low stress 3-D packaging methodologies based on chip on board and plastic leadless chip carriers are discussed.     

PNIPAM: a thermo-activated nano-material for use in optical devices

In this paper 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 self-assemblies 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 632 nm 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 300 ms and 5 s, respectively) due to the non-optimised thermal addressing scheme. In addition, spectral measurements taken in the infrared spectrum (700–1,000 nm) demonstrate that the cell response is flat over a large portion of the infrared spectrum in both the transparent and the diffusing states.