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The ever-increasing exchange of people and goods these last decades creates pandemic risks that should be prevented by containing the hazardous antigens in the region of the outbreak. Therefore, the rapid detection of a biological entity is critical to tackle this issue and others like environment contamination and bioterrorism.Consequently, a multidisciplinary project between Sorbonne Université in Paris and RWTH University in Aachen has been conducted to create a completely integrated lab-on-a-chip (LOC) for easy, rapid and cost-effective immunoassays.The pathogen sensing system is composed of a microfluidic channel surrounded by planar PCB microcoils, which are responsible for the emission and the detection of magnetic fields. This system allows the detection of magnetic nanoparticles (MNP) used for immunoassays in a “sandwich” antigen-antibody configuration. Using microfluidics allows us to test very small volume samples quickly. We successfully tested this device with different concentrations of nanoparticles, different microfluidic channel layouts, different types of nanoparticles and different materials for the microfluidic channel. Using the frequency mixing magnetic detection technique, a LOD of 15 ng/µL for 20 nm core sized MNP has been achieved with a sample volume of 14 µL corresponding to a drop of blood. Antibody coating was also achieved on a Poly(methyl methacrylate) (PMMA) surface which is a more suitable material than the classically used polydimethylsiloxane (PDMS) for our application. In this thesis, emphasis is put on the improvement of the device prototype and the surface functionalization of the microfluidic channel with antibodies.; L’augmentation continue de la circulation des populations et des biens ces dernières décennies accentue les risques de pandémie due à un mauvais confinement des antigènes dangereux à leur région d’apparition. Il est donc crucial de développer une technique rapide de détection de pathogène pour prévenir ces risques. Un projet multidisciplinaire a donc était mis en place entre Sorbonne Université à Paris et RWTH University à Jülich pour le développement d’un dispositif laboratoire-sur-puce intégré pour effectuer des tests immunologiques rapides, faciles et abordables. Ce dispositif de détection de pathogène est composé d’un canal microfluidique entouré de microbobines planaires en circuit imprimé responsables de l’émission et de la détection de champs magnétiques. Ainsi des nanoparticules magnétiques peuvent être détectées et quantifiées puis être corrélées à la présence du pathogène, en tant que marqueurs du test immunologique. Habituellement, l’étape de détection de la présence du pathogène dans un échantillon se fait grâce à un signal fluorescent ou électrochimique qui sont des techniques longues et avec une sensibilité limitée. En conséquence, les tests immunologiques magnétiques semblent être une alternative intéressante. L’utilisation de canaux microfluidiques permet de n’utiliser qu’une très petite quantité d’échantillon pour effectuer un test. Pendant ce doctorat, l’objectif principal a été d’améliorer le prototype du dispositif et la fonctionnalisation de surface du canal microfluidique avec des anticorps.

International audience; We develop a completely integrated Lab-on-Chip (LoC) for easy, rapid and cost-effective immunoassays. The pathogen sensing system is composed of a microfluidic channel surrounded by planar microcoils which are responsible for the emission and the detection of magnetic fields. The system allows the detection and quantification of superparamagnetic beads used for immunoassays in a “sandwich” antigen-antibody configuration. We successfully tested this device with different concentrations of nanoparticles and determine the limit of detection of the prototype. These results are promising and are a step toward the creation of a portable pathogen sensing device.

A magnetic frequency mixing technique with a set of miniaturized planar coils was investigated for use with a completely integrated Lab-on-Chip (LoC) pathogen sensing system. The system allows the detection and quantification of superparamagnetic beads. Additionally, in terms of magnetic nanoparticle characterization ability, the system can be used for immunoassays using the beads as markers. Analytical calculations and simulations for both excitation and pick-up coils are presented, the goal was to investigate the miniaturization of simple and cost-effective planar spiral coils. Following these calculations, a Printed Circuit Board (PCB) prototype was designed, manufactured, and tested for limit of detection, linear response, and validation of theoretical concepts. Using the magnetic frequency mixing technique, a limit of detection of 15 &micro, g/mL of 20 nm core-sized nanoparticles was achieved without any shielding.

International audience; Magnetic nanoparticles are commonly used in numerous applications such as magnetic resonance imaging (MRI), local hyperthermia treatment, magnetic separation, information storage, and medical diagnostics using magnetic immunoassays. The latter field has become increasingly popular in the last years because of the favorable properties of magnetic particles. In fact, the particles can be used both for magnetic actuation as well as for magnetic detection of biomolecules. In the case of immunoassays, the magnetic beads are bound to the biological target substance using the highly specific antibody-antigen interaction. The most common assay format is the sandwich immunoassay in which the analyte is captured by an immobilized primary antibody and the streptavidin-coated magnetic particles are bound to the analyte by a biotinylated secondary antibody. This article reports the conception and realization of a magnetic detection system that encompasses a microfluidic structure along with multilayer designed set of planar coils in a printed circuit board (PCB). The challenge is to measure the magnetic marker particles with high accuracy and high selectivity using a small quantity of biological sample. The magnetic frequency mixing technique is very well suited for this purpose of immunoquantification. For this concept, analytical calculations along with Comsol Multiphysics simulations have been achieved to optimize the dimensions of the coils and the microfluidic reservoir.