Ion sensitive field effect transistor based on graphene and ionophore hybrid membrane for phosphate detection

Microsystem Technologies - This paper reports ion sensitive field effect transistor (IS-FET) with graphene/ionophore hybrid membrane for phosphate detection. CVD graphene is used as a sensing...     

Shear effect on dynamic behavior of microcantilever beam with manufacturing process defects

This paper is concerned with the investigation of the shear effect on the dynamic behavior of a thin microcantilever beam with manufacturing process defects. Unlike the Rayleigh beam model (RBM), the Timoshenko beam model (TBM) takes in consideration the shear effect on the resonance frequency. This effect become significant for thin microcantilever beams with larger slenderness ratios that are normally encountered in MEMS devices such as sensors. The TBM model is presented and analyzed by numerical simulation using Finite Element Method (FEM) to determine corrective factors for the correction of the effect of manufacturing process defects like the underetching at the clamped end of the microbeam and the nonrectangular cross section of the area. A semi-analytical approach is proposed for the extraction of the Young’s modulus from 3D FEM simulation with COMSOL Multiphysics software. This model was tested on measurements of a thin chromium microcantilever beam of dimensions (80 × 2 × 0.95 μm³). Final results indicate that the correction of the effect of manufacturing process defects is significant where the corrected value of Young’s modulus is very close to the experimental results and it is about 280.81 GPa.

     

Advanced etching of silicon based on deep reactive ion etching for silicon high aspect ratio microstructures and three-dimensional micro- and nanostructures

Different processes involving an inductively coupled plasma reactor are presented either for deep reactive ion etching or for isotropic etching of silicon. On one hand, high aspect ratio microstructures with aspect ratio up to 107 were obtained on sub-micron trenches. Application to photonic MEMS is presented. Isotropic etching is also used either alone or in combination with anisotropic etching to realize various 3D shapes.     

Study of black silicon obtained by cryogenic plasma etching: approach to achieve the hot spot of a thermoelectric energy harvester

In this paper, we study the enhanced absorption properties of micro/nano structured silicon surface under incident electromagnetic illumination and its capacity to convert light into heat. We simulate the optical reflectance of three-dimensional micro/nano silicon cones of different dimensions and under different electric field incident angles (θ _i ). According to the favorable simulation results, we fabricate black silicon with conical microstructures that exhibits excellent anti-reflectivity behavior. Plasma etching under cryogenic temperatures is used for this purpose in an inductively coupled plasma-reactive ion etching reactor. The reflectance of the black silicon is measured to be approximately 1?% in the optical wavelength range, by using an integrating sphere coupled to a calibrated spectrometer. Furthermore, a device integrating a resistance temperature detector in a black silicon area is developed in order to investigate its efficiency as a photo-thermal converter.     

Movable vertical mirror arrays for optical microswitch matrixes andtheir electromagnetic actuation

Movable vertical mirror arrays optical microswitch matrixes and their electromagnetic actuation with microcoils are presented as an extension of previous results on a first prototype of microswitch (Helin et al., 2000) a new mechanical design is developed to further increase the density of integration of the optical bypass. Deep reactive ion etching and KOH etching are successively used to realize the whole structure getting the advantages of both (self-alignment between vertical smooth mirrors and fiber guides). Microcoils are fabricated in order to actuate the microswitches electromagnetically. Efforts are done to increase the electromagnetic force generated by the microcoils in order to allow down scaling the sizes and large displacements of the microswitch movable parts in the same dimensions as the optical fibers. A high aspect ratio SU8 pattern and the use of ferromagnetic materials should achieve these requirements     

Thermal conductivity and thermal boundary resistance of nanostructures

   

We present a fabrication process of low-cost superlattices and simulations related with the heat dissipation on them. The influence of the interfacial roughness on the thermal conductivity of semiconductor/semiconductor superlattices was studied by equilibrium and non-equilibrium molecular dynamics and on the Kapitza resistance of superlattice's interfaces by equilibrium molecular dynamics. The non-equilibrium method was the tool used for the prediction of the Kapitza resistance for a binary semiconductor/metal system. Physical explanations are provided for rationalizing the simulation results.     

Microsystem With Fluidic and Optical Interface for Inline Measurement of ${rm CO}_{2}$ in Oil Fields

Motivated by the need for inline measurements in natural gas and oil exploitation, we developed a microfluidic system which is suitable for chemical measurements by optical methods. It consists of a microfluidic system allowing the separation of gas and liquid phases so that gas can be optically analyzed. This system takes advantage of surface tension effects in tiny microchannels. The application is the measurement of carbon dioxide (CO₂) concentration by evaluating absorption of infrared light at a wavelength of 4.24 mum. Measurements have been successfully performed in the 0-70 bars pressure range.     

Design, modeling and characterization of stable, high Q-factor curved Fabry�CP��rot cavities

In this paper, we introduce a novel design for high performance silicon-based Fabry?CPérot cavities and their corresponding design model. According to the design model, the new design shows higher stability, lower insertion loss and higher quality factor Q. Our methodology was based, on one hand, on taking advantage of light reflection and refraction over curved surfaces with curvatures along 2 orthogonal directions, in order to confine the Gaussian beam inside the cavity, thus reducing loss due to beam divergence. Such design enables approaching new limits, where Q-factor is mainly governed by the mirrors reflectance. On the other hand, the use of Bragg reflectors, obtained by DRIE etching enables reaching reflectances above 99%, thus enabling very high Q-factors.