Philippe Laval

X-ray microfocussing combined with microfluidics for on-chip X-ray scattering measurements

This work describes the fabrication of thin microfluidic devices in Kapton (polyimide). These chips are well-suited to perform X-ray scattering experiments using intense microfocussed beams, as Kapton is both relatively resistant to the high intensities generated by a synchrotron, and almost transparent to X-rays. We show networks of microchannels obtained using laser ablation of Kapton films, and we also present a simple way to perform fusion bonding between two Kapton films. The possibilities offered using such devices are illustrated with X-ray scattering experiments. These experiments demonstrate that structural measurements in the 1 A-20 nm range can be obtained with spatial resolutions of a few microns in a microchannel.

Breakage of macroporous alumina beads under compressive loading: simulation and experimental validation

Abstract Catalyst carrier beads used in the oil industry experience various kinds of breakage during their residence time in reactors. These beads are highly porous in order to have a large surface area and contain macropores to enhance the transport of the reagents within the beads. However, high porosity and the presence of macropores weaken the beads, and therefore an optimisation of these parameters is highly desirable. In order to analyse the influence of these macropores on the particle strength, the behaviour of the beads under quasi-static compressive loading has been analysed and compared for three samples with different macroporosities. The distributions of the single particle crushing strength and Youngs modulus have been obtained for each sample. The numerical technique of distinct element analysis (DEA) has been applied to analyse the bulk crushing strength (BCS) of each sample. The BCS of one of the samples has also been determined experimentally and the results are compared with the predictions from DEA in an attempt to relate the bulk behaviour to the single particle characteristics in order to ultimately optimise the production of the beads.

Investigating Kinetics of Temperature-Dependent Processes Using Microfluidics

We have developed an original microfluidic system to study fast kinetics of temperature-dependent processes in an emulsion. Using flow focusing geometries, aqueous droplets are continuously formed in an oil flow. These droplets, acting as microreactors (100 nL), contain the solution to be investigated, and are formed at high temperature. They flow in a microchannel to a cooled area through a controlled temperature gradient (typically from 60 to 10°C in a few seconds). Along the microchannel, the distance being equivalent to the time thanks to the use of droplets, the kinetics of the process can be followed (from 10 to 300 s). In particular, the microdevice has been used to study the kinetics of crystal nucleation of a solute dispersed in water after a temperature quench.Copyright