Réda Yahiaoui

Improving immunosensor performances using an acoustic mixer on droplet microarray

A major drawback of protein microarrays is the lack of control of ligand immobilization at the surface of the chip which limits their performances and thus their impacts in in vitro diagnosis. To improve antibody (Ab) grafting during the spotting process on commercialized gold SPRi chips, we propose to produce a chaotic flow in every spotted droplet, by using an acoustic field, in order to disrupt the steady state of the reaction of Ab grafting. Our results show that acoustic mixing during Ab binding at the biochips surface increases their biorecognition performances of a mean factor of 2.7 in comparison with Ab layer grafted in a passive mode. Moreover, it increases statistically the homogeneity of the response over all the surface of the chips.

Micropositioning and Fast Transport Using a Contactless Micro-Conveyor

Guillaume J. Laurent *, Anne Delettre, Rabah Zeggari, Reda Yahiaoui, Jean-Franc¸ois Manceauand Nadine Le Fort-PiatFEMTO-ST Institute, UFC-ENSMM-UTBM-CNRS, Universite de Franche-Comt´ e,´Besanc¸on 25000, France; E-Mails: anne.delettre@femto-st.fr (A.D.); rabah.zeggari@femto-st.fr (R.Z.);reda.yahiaoui@femto-st.fr (R.Y.); jfmanceau@femto-st.fr (J.-F.M.); nadine.piat@ens2m.fr (N.L.F.-P.)* Author to whom correspondence should be addressed; E-Mail: guillaume.laurent@ens2m.fr;Tel.: +33-3-8140-2808; Fax: +33-3-8140-2809.Received: 28 November 2013; in revised form: 16 December 2013 / Accepted: 6 February 2014 /Published: 12 February 2014Abstract: The micro-conveyor is a 9 9 mm

Controlled modification of electrochemical microsystems with polyethylenimine/reduced graphene oxide using electrophoretic deposition: Sensing of dopamine levels in meat samples

Microsystems play an important role in many biological and environmental applications. The integration of electrical interfaces into such miniaturized systems provides new opportunities for electrochemical sensing where high sensitivity and selectivity towards the analyte are requested. This can be only achieved upon controlled functionalization of the working electrode, a challenge for compact microsystems. In this work, we demonstrate the benefit of electrophoretic deposition (EPD) of reduced graphene oxide/polyethylenimine (rGO/PEI) for the selective modification of a gold (Au) microelectrode in a microsystem comprising a Pt counter and a Ag/AgCl reference electrode. The functionalized microsystem was successfully applied for the sensing of dopamine with a detection limit of 50nM. Additionally, the microsystem exhibited good performance for the detection of dopamine levels in meat samples.

FEM Analysis for the Influence of Manufacturing Process Defects on Dynamic Behavior of Thin Chromium Microbeam

This paper identifies and investigates the influence of technological defects of manufacturing process on the dynamic behavior of thin chromium microbeam. The analytical models will be analyzed and corrected using finite element method (FEM) to determine their validity under influence of technological defects. A semi-analytical model will be proposed for the extraction of corrective factors from 3D FEM simulation of dynamic behavior of microbeam. Final results indicate that the correction of technological defects is very significant for Cr microbeam 80x2x0.95μm3. In other hand, the corrected value of Young’s modulus is very close to the experimental results and it is about 279.1GPa.

FPGA-Based HD Camera System for the Micropositioning of Biomedical Micro-Objects Using a Contactless Micro-Conveyor

With recent advancements, micro-object contactless conveyers are becoming an essential part of the biomedical sector. They help avoid any infection and damage that can occur due to external contact. In this context, a smart micro-conveyor is devised. It is a Field Programmable Gate Array (FPGA)-based system that employs a smart surface for conveyance along with an OmniVision complementary metal-oxide-semiconductor (CMOS) HD camera for micro-object position detection and tracking. A specific FPGA-based hardware design and VHSIC (Very High Speed Integrated Circuit) Hardware Description Language (VHDL) implementation are realized. It is done without employing any Nios processor or System on a Programmable Chip (SOPC) builder based Central Processing Unit (CPU) core. It keeps the system efficient in terms of resource utilization and power consumption. The micro-object positioning status is captured with an embedded FPGA-based camera driver and it is communicated to the Image Processing, Decision Making and Command (IPDC) module. The IPDC is programmed in C++ and can run on a Personal Computer (PC) or on any appropriate embedded system. The IPDC decisions are sent back to the FPGA, which pilots the smart surface accordingly. In this way, an automated closed-loop system is employed to convey the micro-object towards a desired location. The devised system architecture and implementation principle is described. Its functionality is also verified. Results have confirmed the proper functionality of the developed system, along with its outperformance compared to other solutions.

Electrogeneration of Diiodoaurate in Dimethylsulfoxide on Gold Substrate and Localized Patterning

A localized etching of gold surface by scanning electrochemical microscope technique is presented where a dimethylsulfoxide-based electrolyte charged with iodine is used. The electrogenerated triiodide ion at the platinum ultramicroelectrode tip (feedback mode) acts as an oxidant for gold surface. The effects of electrode diameter and the bias time have been investigated. The approach curve method was used to hold the electrode tip close to the gold surface. A scanning electron microscope is used to observe the etched gold surfaces where disk-shaped dots are generated. The diameter of these holes depends directly on the Pt electrode diameter and the bias time.

An FPGA Based Resources Efficient Solution for the OmniVision Digital VGA Cameras Family

Camera is an elementary component of the modern systems employed in robotics, defense, surveillance, automation, etc. In order to keep the system compact, embedded camera solutions are developing. A proper system integration requires an effective camera driver. In this context, an efficient FPGA based digital camera driver is devised. The proposed solution is compatible with most of the Omni Vision digital cameras. The developed system functionality is verified with a developed testing methodology. The system on chip implementation resources are computed. It shows that the devised solution outperforms compared to the coexisting ones in terms of resources utilization.

Analytical modeling of mechanical behavior of structures: Comparative analysis, experimental validation and numerical correction with FEM of material defects generated by anisotropic etching

This paper presented semi-analytical approach in order to investigate the influence of manufacturing process defects on the elasticity of thin microbeam. The Rayleigh Beam Model (RBM) will be analyzed and corrected using 3D FEM scripts including the effects of the cross-section shape and the under-etching. This model was tested on measurements of thin chromium microbeam of dimensions (80 × 2 × 0.95 μm 3 ). The results show that the influence of defects is very significant for the extracted value of Youngs modulus where it is very close to the measured value and it is about 279.1 GPa.

Performing microdroplets mixing using an acoustic transducer with low vibration frequencies

In this paper, we introduce a parallel microdroplet mixing strategy based on local acoustic field generation using low frequency vibrations. An active acoustic mixer array was designed and fabricated. This microfluidic device permits the creation in parallel of an active mixture in a matrix of 25 microdroplets that are localized on a surface. It was designed to avoid contamination between droplets while they are excited. Experiments showing the active mixture of droplets will be presented.