Production of microdroplets and microparticles
Droplets, particles and capsules, from the micro- to the nanoscale, are the building blocks of many products in pharmacy, food and chemistry, and their size and structure define how they behave, for example how fast a drug is released. Microfluidics gives precise control over how they are formed, one droplet at a time, and can be scaled up by running many generators in parallel. We design microfluidic devices to produce monodisperse droplets, microparticles, capsules and nanoparticles, and to control each step from droplet formation to the final particle. Applications include drug-loaded PLGA microparticles for beta cell therapy, where the solvent extraction step is controlled directly in the chip, and polymer-lipid hybrid microparticles with internal nanostructures. The same droplets can also act as small reactors for antisolvent crystallization, giving better control over crystal size and form.
Ind. Eng. Chem. Res. 2020; Colloids Surf. A 2024; Chem. Eng. Sci. 2025; Pharmaceutics 2026
Manipulation and separation of particles and cells in flow
Many processes need particles or cells to be concentrated, washed or sorted before they are analyzed or used. We use acoustic standing waves (acoustofluidics) to focus and concentrate particles and cells without contact or labels, and we explore the operating limits of this technique, from cell suspensions to sub-micron particles. Combined with Raman spectroscopy, acoustic trapping allows microparticles to be analyzed directly in water. We also showed that rail structures in a channel can move particles from one liquid to another across two co-flowing streams without mixing them, a promising way to wash or transfer particles in continuous flow.
Sci. Rep. 2022; Appl. Microbiol. Biotechnol. 2024; Sens. Actuators B 2024
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ature-inspired water management on structured surface
Plastic mulch films are widely used in agriculture but leave microplastics in the soil. In the EIC Pathfinder project CELLAGRI, we develop fully biodegradable cellulose-based films equipped with microfluidic structures inspired by nature, which guide water droplets and help retain them where plants need it. At VUB, we focus on how rain and dew water can be guided on open surfaces, passively and without any external energy. When droplets land on a film, their path depends on the surface: by designing it, we can make water move preferentially in one direction rather than the other, for example toward the plant and away from the edges. To achieve this, we combine microstructures, which shape the path of the liquid, with coatings that tune the wettability of the surface. We design and simulate these surfaces, fabricate them, and test how droplets spread, move and are collected under realistic conditions.
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ortex-enhanced chromatography and instrumentation
In liquid chromatography, the spreading of the sample along the column (axial dispersion) limits separation performance, especially in miniaturized columns. Creating lateral vortices across the channel can reduce this spreading. We study, by simulation and experiment, how vortices generated by Acoustics or/and AC electroosmotic flow, using electrodes integrated in the channel walls, can improve separation in open tubular and tapered columns. This work includes the development of the chips and the instrumentation around them.
J. Chromatogr. A 2024; J. Chromatogr. A 2026
Centri
fugal lab-on-a-disc platforms
Centrifugal microfluidics moves liquids by simply spinning a disc, without pumps or tubing, which makes it attractive for low-cost and portable devices. We develop polymer discs and functionalize them for different applications: preparing many dilutions in parallel to replace repetitive pipetting, screening chemical and biological conditions, and separating and quantifying parasite eggs in samples. We also use lab-on-a-disc platforms for outreach, for example to demonstrate blood typing at the I Love Science Festival in Brussels.
Platelets production in microfluidic bioreactors
Platelets are small blood cells that prevent bleeding. They are formed by fragmentation of precursor cells called megakaryocytes (MK). In vivo, this process, called thrombopoiesis, starts in the bone marrow, where mature MK reside and extend long cytoplasmic branches into the sinusoidal blood capillaries. Aided by the bloodstream, the tips of these extensions are released in the circulation and undergo fissions that produce platelets. We developed a microfluidic bioreactor to produce platelets from MK in vitro. MK are trapped inside a microfluidic chamber. Then, a high shear stress is imposed to elongate and rupture the cells into platelets. This work was supported by the Hauts de France region and the FEDER funds.
Particles
-induced fingering instability
Interfacial two-phase flows are critical in many natural and industrial processes, including flows in porous media, petroleum extraction, and microfluidic two-phase flow. An instability of the interface, known as the Saffman-Taylor instability, can occur when a low viscosity fluid displaces one of higher viscosity. It results from the decrease of the flow resistance as the fluid of lower viscosity replaces the more viscous one. While the inverse situation is generally stable, we show in this study that the presence of microparticles on the walls can modify this equilibrium and leads to the generation of finger patterns. Such process might occur naturally in cleaning processes where bacteria, spores, dust or particles are present on surfaces and dramatically affect the underlying dynamics.
Phys. Rev. Lett. 2016
Flow focusing of two miscible fluids in a microfluidic junction
When a liquid is injected into another surrounding liquid, it is called flow focusing or co-flow. This can be used to create fibers, droplets or to align micro particles or cells. We experimentally investigate the influence of imposing pressure to generate co-flow in a cross-junction microfluidic device. A state diagram is constructed. Furthermore, we characterize the jet width as a function of the viscosity contrast, the inlet pressures, the flow rates and the channel aspect ratio. This study defines the conditions needed to create a co-flow regime with a specific jet width using a pressure driven flow.
Phys. Fluids 2019
Vibration of cylindrical armored bubble
A bubble covered with a monolayer of particles is called an armored bubble. We developed a microfluidic technique to create cylindrical bubbles covered by a monolayer of microparticles and studied their response to vertical mechanical vibration. We observed that the bubble surface shrinks as the excess particles are released into the liquid. This study opens perspectives for the localized release of pharmacological agents in the body.
Soft Matter 2017
Motion of an ellipsoid particle near a wall
The motion of an ellipsoidal particle near a wall is of major interest for biological and industrial applications, for example the motion of bacteria before and after they adhere to a wall, or the motion of platelets in blood vessels. We developed a numerical code based on the Boundary Element Method (BEM) to study this motion. Elongated ellipsoids (rugby-ball shape) and flattened ellipsoids (platelet shape) were studied in non-inertial flow at low concentrations. Our results give a complete picture of the particle dynamics over a wide range of aspect ratios, orientations and wall distances..
Effect of drying on the resistance to detachment of Bacillus spores
The agri-food industry faces recurring problems of bacterial and biofilm adhesion (e.g., Escherichia coli, Listeria, Bacillus cereus and Bacillus subtilis spores) on the walls of food production lines. These microorganisms often go through a drying step before adhering. We studied how drying conditions affect the resistance to detachment of three types of bacterial spores and of microbeads. Samples were dried on glass slides at different temperatures and for different durations, then water was flowed through a microfluidic chip to detach them. We showed that both the duration and the temperature of drying affect the resistance to detachment. Colloids Surf. B 2016
