Tahar Kezai

Miniaturized Wireless Sensing System for Real-Time Breath Activity Recording

A portable, non-invasive and easy to operate wireless system has been developed for monitoring the breathing activity of patient. The system is composed of a capacitive microsensor (airflow-humidity sensor) integrated on a silicon chip and of a Negative Temperature Coefficient thermistor; both are connected to a wireless network to allow efficient healthcare at home as well as in hospitals. The capacitive sensitive part of the microsensor is an array of interdigitated metallic electrodes covered by 100-nm-thick dense anodized aluminum oxide layer. The breath water vapor is adsorbed over the interdigitated electrodes and changes the sensor characteristic capacitance by up to two orders of magnitude. This modulated signal is then digitized and either stored in a memory or directly transmitted to a monitor through a short distance radio frequency (RF) link. Results show that the wireless platform can be powered by two AAA batteries and deployed in a mesh or star configuration as wireless sensor network. Full size of the microsensor is less than 1 cm2 and is conveniently implemented in a classical adhesive bandage or in nasal prongs. This microsystem is proposed for monitoring sleep-disordered breathing as well as breathing rhythm of athletes during effort.

New Approach for Improvement of Secondary Ion Mass Spectrometry Profile Analysis

In this paper, we describe the improvement of secondary ion mass spectrometry (SIMS) profile analysis by a new approach based on partial deconvolution combined with scale-frequency shrinkage. The SIMS profiles are obtained by analysis of the delta layers of boron doped silicon in a silicon matrix, analyzed using Cameca-Ims6f at oblique incidence. These profiles can be approximated closely by exponential-like tail distributions with decay length, which characterizes the collisional mixing effect. The partial deconvolution removes the residual ion mixing effect. The contributions of high-frequency noise are removed by shrinkage to a great extent of the profiles. It is shown that this approach leads to a marked improvement in depth resolution without producing artifacts and aberrations caused principally by noise. Furthermore, it is shown that the asymmetry of the delta layers, caused by the collisional mixing effect, is completely removed, the decay length is decreased by a factor of 4 compared with that before deconvolution.

Experimental evidence of mounting grooves and serration patterns on fin lines characteristics

In this paper, the mounting grooves and serration patterns of fin line circuits are investigated experimentally. Our measurements show that the short-circuit ended mounting grooves degrade seriously the insertion loss of fin lines at the low frequencies of the band. The open ended mounting grooves are found better for fin lines applications and measurements. An improvement of 0.7 dB is observed over the whole band, when the serration patterns of the fin line are placed into the open-ended mounting grooves. These results can be used for measuring the losses and for designing transitions or other fin line circuits.

Improvement of Depth Resolution in Secondary Ion Mass Spectrometry Analysis Using Multiresolution Deconvolution

Multiresolution deconvolution (MD), based on Tikhonov-Miller regularization and wavelet transformation, was developed and applied to improve the depth resolution of secondary ion mass spectrometry (SIMS) profiles. Both local application of the regularization parameter and shrinking the wavelet coefficients of blurred and estimated solutions at each resolution level in MD provide to smoothed results without the risk of generating artifacts related to noise content in the profile. This led to a significant improvement in the depth resolution. The SIMS profiles were obtained by analysis of delta layers of boron in a silicon matrix using a Cameca-lms6f instrument. The results obtained by using the MID algorithm are compared to those obtained by monoresolution deconvolution which is Tikhonov-Miller regularization with a model of solution (TMMS). Finally, the advantages and limitations of the MD algorithm are presented and discussed

Wireless microsensors system for monitoring breathing activity

A portable, non-invasive and easy to operate wireless system has been developed for monitoring the breathing activity of patient. The system is composed of a capacitive microsensor (airflow-humidity sensor) integrated on a silicon chip and of a Negative Temperature Coefficient thermistor; both are coupled to a Radio Frequency wireless link. The sensitive part of the microsensor is an array of interdigitated metallic electrodes covered by 100 nm-thick dense anodized aluminum oxide layer. The breath water vapor is adsorbed over the interdigitated electrode and changes the sensor characteristic capacitance. This modulated signal is then digitized and either stored in a memory or directly transmitted to a monitor through the short distance RF link. Full size of the microsensor is less than 1 cm/sup 2/ and can be easily implemented in a classical adhesive bandage. This microsystem is proposed for monitoring sleep-disordered breathing as well as breathing rhythm of athletes during effort.

PENELOPE : a micro- and near mm-waves CAD/CAM software designed as an educational tool

The paper describes a software developed by the authors as an educational tool for the design of microwave and near millimeter wave circuits, up to 40 Ghz. The software is part of a whole, by which passive and active circuits can be designed, printed and tested in planar technology (microstrips, finlines and coplanar structures). The facility is available to last year students and to practicing engineers. Since two years, it has been used for various configurations, up to 40 Ghz.

Fast location and accurate computation of higher order, evanescent, and complex modes in unilateral fin lines

Shielded multilayered structures are commonly used in MIC circuits up to 140 GHz. This paper describes an original method to accurately calculate the complex propagation constant of shielded multilayered structures with minimal computational effort. The method combines singular value decomposition and poles location technique. In order to construct the complete spectrum of the multilayered structure, the poles detected are used to ensure that no modes are missed. It is shown that this accurate method elimiates difficulties related to poles and steep gradients in finding the complex propagation constant of the multilayered structure. Numerical results are compared first to those calculated by zero detection method and second to data obtained by singular integral equation.

Rigorous computation of FIN line higher order modes by using singular value decomposition in immittance approach

Unilateral fin line higher order modes are computed in a way which leads to their fast location and ensures that the desired accuracy is achieved. Singular Value Decomposition is introduced in spectral domain Inunittance Approach to obtain the propagation coefficients of higher order and evanescent modes. By doing so, problems related to poles are eliminated and the accuracy is improved. Numerical results are compared to theoretical and experimental results, and show an excellent agreement.

Modeling resonance in waveguide-to-microstrip junctions by unilateral fin line resonators

A method for the rigorous calculation of the resonant frequencies observed in waveguide-to-microstrip transitions is developed. The method is general and includes all types of waveguide-to-microstrip junctions. The resonant parts are modeled as unilateral fin line resonators with similar shapes. The resonance frequencies are determined by using the Spectral Domain Approach with appropriate basis functions. Measurements were made. They are in good agreement with the data computed from the model. >