Applicative Systems

This page presents a summary of three applied systems that have been developed in the laboratory. First, we show the technique of printing hydrophobic/hydrophilic tracks using local heating resistors that allow to accelerate the natural hydrophobic recovery of PDMS after oxygen plasma treatment. In a second section, the shape optimization technique of heating resistors that allowed to generate controlled temperature profiles in microfluidic cavities is presented. Finally, the system that allowed to generate a homogeneous injection of liquid through a matrix of microneedles is summarized. This injection is performed homogeneous regardless of the hydrodynamic resistance at the exit of the matrix (the skin not being a homogeneous material).


Under construction...

Optimized resistor pattern

Part of the PhD thesis of Bertrand SELVA

This part is related to the controle of temperature within a microfluidic cavity using heating resistor that have been shape optimized.

Generating a constant temperature gradient within a microfluidic cavity

We demonstrate the possibility of generating high-temperature gradients with a linear temperature profile when heating is provided in situ. Thanks to improved optimization algorithms, the shape of resistors, which constitute the heating source, is optimized by applying the genetic algorithm NSGA-II (acronym for the non-dominated sorting genetic algorithm) (Deb et al 2002 IEEE Trans. Evol. Comput. 6 2). Experimental validation of the linear temperature profile within the cavity is carried out using a thermally sensitive fluorophore, called Rhodamine B (Ross et al 2001 Anal. Chem. 73 4117–23, Erickson et al 2003 Lab Chip 3 141–9). The high level of agreement obtained between experimental and numerical results serves to validate the accuracy of this method for generating highly controlled temperature profiles. In the field of actuation, such a device is of potential interest since it allows for controlling bubbles or droplets moving by means of thermocapillary effects (Baroud et al 2007 Phys. Rev. E 75 046302). Digital microfluidics is a critical area in the field of microfluidics (Dreyfus et al 2003 Phys. Rev. Lett. 90 14) as well as in the so-called lab-on-a-chip technology. Through an example, the large application potential of such a technique is demonstrated, which entails handling a single bubble driven along a cavity using simple and tunable embedded resistors.

Integration of a uniform and rapid heating source into microfluidic systems

Selva et al., J. Micromech. Microeng., 2009

Integration of a uniform and rapid heating source into microfluidic systems

in collaboration with Pascaline Mary

The purpose of this study has been to demonstrate the possibilities of uniform heating of a cavity, with great accuracy, by means of an integrated resistor built with the same dimensions as the cavity, i.e., with a high level of integration. For application purposes, a compact resistor allows increasing the number of cavities in which temperature can be independently controlled on the same substrate, which can prove critical for high-throughput screening applications. Potential applications lie in the field of biology or chemistry. In order to achieve the desired result, an optimization procedure was performed on the shape of the resistor. The heater size reduction enables a high level of integration with a reduced heating source surface area. Resistor shape has been optimized to reduce the influence of boundary effects, using improvements introduced in genetic algorithms. An experimental validation of the temperature profile inside the cavity has been carried out using a dye whose fluorescence depends on temperature, i.e., Rhodamine B, it will be shown herein that the optimized resistor allows for temperature cycling, e.g., for PCR applications.

Selva et al., Microfluids Nanofluids 2010.

Homogeneous transdermal injection

STREP ANGIOSKIN, coordinator : L. Mir IGR, UMR 8121,

in collaboration with G. Cabodevilla (Institut FEMTO-ST,LPMO, UMR 6174) (consortium agreement LSH-2003-512127)

DNA electrotransfer of plasmids coding for antiangiogenic factors as a proof of principle of non-viral gene therapy for the treatment of skin disease,

PhD thesis of Antonin HOËL

Hoel et al., J. Micromech. Microeng., 2008

Daugimont et al., Journal of Membrane Biology, 2010

We report a microfluidic device able to control the ejection of fluid through a matrix of out-of-plane microneedles. The device comprises a matrix of open dispensing units connected to needles and filled by a common filling system. A deformable membrane (e.g. in PDMS) is brought into contact with the dispensing units. Pressure exerted on the deformable membrane closes (and thus individualizes) each dispensing unit and provokes the ejection of the dispensing unit content through the outlets. Sufficient pressure over the deformable membrane ensures that all dispensing units deliver a fixed volume (their content) irrespective of the hydrodynamic pressure outside the dispensing unit outlet. The size of the ensemble matrix of dispensing units, the number of liquid reservoirs, as well as the material can vary depending on the considered application of the device or on the conditions of use. In the present paper, the liquid reservoirs are geometrically identical. The geometrical parameters of the device are optimized to avoid as much dead volume as possible, as it was to handle plasmid DNA solutions which are very expensive. The conception, the fabrication and the experimental results are described in this paper. Our prototype is conceived to inject in a uniform way 10 μl of drug through 100 microneedles distributed over 1 cm2.

European patent : 06425292.7 (2006)

US application number : 12/226,883 "Fluid dispensing system"