Publications by Abdeljalil Sayah

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We present an active fixed-volume mixer based on the creation of multiple source–sink microfluidic flows in a polydimethylsiloxane (PDMS) chip without the need of external or internal pumps. To do so, four different pressure-controlled actuation chambers a ...

We present the photosensitive flexopolymer PRISM as a new promising material for the realization of thick optical components. The PRISM flexopolymer can be directly polymerized using conventional UV exposure and is simply developed in a water-based solutio ...

We characterise computationally and experimentally a three-dimensional (3D) microfluidic passive mixer for various Reynolds numbers ranging from 1 to 100, corresponding to primary flow rates of 10-870 mu l min(-1). The 3D mixing channel is composed of mult ...

We have designed and realised a new type of microsystem for the electrical characterisation of arrays of living cells for biomedical diagnostic purposes. We have used deep plasma etching for the fabrication of microholes and micro-fluidic channels in silicon substrates. After oxidation and electrical contact fabrication, these structured silicon wafers have been anodically bonded with Pyrex wafers. The fabrication is completed by the gluing of micro-patterned polyimide foils on top of the silicon. We have t

A new method to realize arrays of micro-lenses using a sol gel glass replication technology is presented. Polydimethyl-siloxane (PDMS) master structures are used for the replication of thin glass membranes, which, by an appropriate annealing procedure, result in converging lenses with positive meniscus. Hereby, we exploit PDMS - sol gel surface interactions and thickness dependent changes in composition of the sol gel solution. The lenses are realized on a circular and square like basis. We characterize the

We have applied the sol-gel process to generate optical microstructures in glass using in-house developed sol-gel materials. The synthesis of our sol-gel glass materials is based on the formation of particles of controlled size from organo-metallic compounds. The overall shrinkage during annealing of the gel material is negligible and does not imply crack formation. Silica, titania and binary oxides of silica titania oxide sol-gel materials have been used. A two-step pattern transfer is employed to replicat

Capillary electrochromatography (CEC) appears ideally suited for high performance separations at small scale, i.e. on a chip. Problems with the reproducible production of the required HPLC column, but also the lack of commercially available CEC instruments have prevented many putative applicants of this promising technique from entering the field. In this paper, a fast and easy way to produce self-containing open-tubular CEC columns (C8-moieties for reversed phase applications) by the sol-gel technique is d

We introduce a new low temperature bonding technology to assemble two microstructured glass substrates for the realization of microchannels for miniaturized chemical analysis applications. To realize the microchannels, we introduce, besides the well-known HF-etching technology, two simple alternative methods, namely sawing and micro-powder blasting. After proper cleaning of the two glass surfaces, direct bonding is obtained just by exposing the glass stack to a high pressure (up to 50 MPa) in the 100-200 °C

We report here a simple method, based on electrostatic self-assembly, for realizing bead-based single protein micro-arrays. We generate positively charged surface micro-patterns on a glass substrate and use them as template for adsorbing negatively-charged ...

The powder-blasting method is used to fabricate structures with a three-dimensional topography in glass using elastomeric masks. The relation between the mask opening width and the erosion depth is exploited to fabricate microstructures with varying depth ...

We introduce powder blasting using a pressurised nozzle and a metallic mask as a new promising technology for microsystem fabrication. We study basic parameters of this powder blasting erosion process as well as mask-geometry effects on the erosion rate. We demonstrate the application potential of this technique in three important fields of microsystems research: (i) the realisation of microfluidic chips for biochemical separations, (ii) the micropatterning of composite hard magnetic layers for mechatronic

We present powder blasting as a new technology for the realization of Micro Electro-Mechanical Systems (MEMS). The technique is base don the erosion of a masked substrate by a high velocity powder beam. We study the erosion rate of the process using glass wafers and introduce oblique powder blasting, where we vary the angle of incidence of the powder beam with respect tot the target surface. The oblique impact gives rise to particular side walls effects of micro patterned hole structures. We have applied th

We report on powder blasting as a promising technology for the three-dimensional structuring of brittle materials. We investigate the basic parameters of this process, which is based on the erosion of a masked substrate by a high-velocity eroding powder beam, using glass substrates. We study the effect of various parameters on the etching rate, like the powder velocity and the mask feature size, which induces geometrical effects to the erosion process. We introduce oblique powder blasting and investigate, i

We have realised a microsystem for the culture and electrical characterisation of epithelial cell layers for cell-based diagnostic applications. The main goal of this work is to achieve both cell culture and impedimetric and potentiometric characterisation on a single device. The miniaturised cell culture system enables the uses of scarce epithelial cells, as obtained from transgenic mice or from human biopsies. The device is completely modular and offers high flexibility: a polycarbonate membrane used as c

We have designed and realised a new type of microsystem for the electrical characterisation of epithelial cell layers for biomedical diagnostic purposes. We have used deep plasma and other micromachining procedures for the fabrication of vias and microfluidic channels in silicon and glass substrates. Miniaturised cell culture devices have been realised by gluing nano-porous polycarbonate membranes in between two structured wafers and by combining these with glass wafers to provide integrated microfluidic ch

We introduce two new low temperature bonding technologies for the assembly of microstructured glass substrates for the realisation of microchannels for miniaturised chemical analysis applications. A first method consists of a proper cleaning of the two glass surfaces, followed by a simple epoxy gluing process at 90°C. In a second method, direct bonding is obtained just by exposing the glass stack to a high pressure (up to 50 MPa) in the 100-200°C temperature range. We obtain bonding strengths as high as 10

We introduce powder blasting for the fabrication of glass microchips. Powder blasting is a fast and cheap technique with which we pattern channels in sodalime and pyrex glass with a width down to 100µm. We combine the technique with appropriate bonding procedures to realise sealed microchannel structures. We study the transport of fluorescent dye solutions and fluorescent beads within channels made by powder blasting and in "classical" channels made by HF-etching. We find a remarkable difference in sign of

We present three-dimensional (3D) micromixers realized in a monolithic glass substrate using a simple oblique powder-blasting microfabrication method and a single photosensitive elastomeric mask. The mixer topology consists of a curved microchannel that incorporates a series of nozzle-diffuser elements buried inside the glass substrate. The strongly varying microfluidic cross-section of these elements and multiple channel bends result in the generation of multiple vortices. This results in achieving a high

We present oblique powder blasting as a three-dimensional micromachining technology for brittle materials. Powder blasting is a microfabrication process, based on the use of a pressurised air beam containing eroding Al2O3 particles. By varying the angle of incidence of the incoming particles to a substrate, covered by a mask, one can exploit the oblique slopes of micropatterned holes and mask underetching phenomena to generate new options for three-dimensional microstructuring. We have identified and quanti

We report here a simple method, based on electrostatic self-assembly, for realizing bead-based single protein microarrays. We generate positively-charged surface micro-patterns on a glass substrate and used them as the template for adsorbing negatively-cha ...

Abdeljalil Sayah

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Chaotic mixing using source-sink microfluidic flows in a PDMS chip

Ultra-thick micro-optical components using the PRISM photosensitive flexopolymer

Understanding the mixing process in 3D microfluidic nozzle/diffuser systems: simulations and experiments

Fabrication of a novel microsystem for the electrical characterisation of cell array

Micro-replication of Optical Lenses in Glass using Sol Gel Technology

The sol-gel process for realisation of optical micro-structures in glass

Utilisation of the sol-gel technique for the development of novel stationary phases for capillary electrochromatography on a chip

Novel low temperature pressure-assisted bonding technology

Bead-based single protein micro-array realized through electrostatic self-assembly of carboxylated beads

Fabrication of microfluidic mixers with varying topography in glass using the powder blasting process

The introduction of powder blasting for sensor and microsystem applications

Powder blasting as a three-dimensional microstructuring technology for MEMS applications

Powder blasting for three-dimensional microstructuring of glass

Modular microsystem for epithelial cell culture and electrical characterisation

Biosystem for the culture and characterisation of epithelial cell tissues

Development of novel low temperature bonding technologies for microchip chemical analysis applications

Powder blasting for the realisation of microchips for bio-analytic applications

Three-dimensional mixers with non-planar microchannels in a monolithic glass substrate using oblique powder blasting

Oblique Powder Blasting for Three-dimensional Micromachining of Brittle Materials

Bead-based protein microarrays realized through electrostatic self-assembly of carboxylated beads