Compartmentalization is a key concept in many technological systems and is a prerequisite for the emergence of life as we know it. A living cell is the result of millions of years of evolutionary processes. The path followed to evolve is driven by series of selection pressures leading to a wide range of functions that have emerged in single self-organized microcompartments. Focusing on one single function, it is likely not fully optimised as the natural selection pressure can be both ill-defined and fluctuating in time : the cell is finally optimised as an intrinsincally complex system and individual functions can therefore be further optimised.
Using microfluidic systems, we manipulate and analyse emulsions as elementary dispersed compartments for the analysis of single cells focussing on specific enzymatic activities. The ultra-high throughput of microfluidic systems provides the basis to analyse large libraries of cells to select the most efficient ones based on a well defined selection pressure. Specific improved variants are then obtained. We use this microfluidic technology for a wide range of biological analysis at the single cell level for screening application.
The microcompartmentalization technology can be extended to fully in vitro approaches for the assay of genes and enzymes (ie circumventing the complexity of cells and focusing on one single function). This reductionist approach points towards minimal cells, a question bridging prebiotic chemistry and the origin of life to modern questions in Synthetic Biology. We aim at addressing (parts of) these questions through active soft matter and biomimetic systems based on functional microcompartments. The key concept is the use of processes out of equilibrium involving interfaces, for example chemical modifications of surfactant, enzymatic catalysis and the control of transport between the inside and outside of the compartment.
Keywords : Microfluidics, Active Soft Interfaces, Biotechnology, High-throughput Screening, Single cells, Synthetic Biology.
We use soft-lithography techniques to produce microfluidic modules taylored for droplet manipulation at high-throughput (~ 10 000 droplets per second). These modules enable production and reinjection of droplets, droplet pairs or muliple emulsion, division of droplet, fusion and dielectrophoretic sorting of droplets.
Microfluidics & Emulsions
The use of microfluidic modules enables the production and control of calibrated droplets. This accurate control on droplet shapes and interfaces provides means to extract quantitative informations on interfaces, in statics and dynamics. We are for example interested in transient states in emulsion stabilisation by surfactants and their link to dynamic surface tensions.
Droplets in External fields
Electric fields in microfluidic channels provides additional level of control on droplet actuation. In electric field, droplets can be actuated at the submillisecond time-scale without the use of mechanical parts. Besides actuation mechanisms, electric fields are used to perturbate the equilibrium of droplet interfaces and initiate droplet coalescence by an electro-hydrodynamic instability of the oil layer between conducting droplets.
Droplet in emulsion behave as independent microreactors that can be used as miniaturized wells for biochemical assays. In collaboration with biologists and biochemists, we use droplets to screen cells, genes and chemical compounds in droplets at a high-throughput in biological applications such as directed evolution, drug screening or diagnostics.
Since January 2013, the group is funded by the ERC Starting Grant Soft Interfaces and by the ERC Proof of Concept FluoSurf from Dec. 2016 until Mai 2018.