Marion Costella defends her PhD on Dec. 14, 2020 at 2:00 PM.
Place : visio conference only
Jury :
Rapporteurs :
Membres : M-C. Julien (Rennes 1), A-C. Salaün (IETR, Rennes 1), L. Leroy (Univ. Grenoble Alpes), J. Moreau (IOGS), M. Canva (LN2, Sherbrooke).
Encadrement : P. Simonet, M. Frénéa-Robin (Ampère)
Abstract :
Biosensors are monitoring tools that provide a quantification of chemical or biological species in a sample. Surface plasmon biosensors use an evanescent electromagnetic wave to detect molecular interactions or biological objects on a metallic film. Functionalizing this metallic film makes it adherent to certain biologic or chemical species, allowing their specific detection. Surface plasmon resonance biosensors provide real-time, label-free, and sensitive measurements, three advantages in comparison with other detection techniques. Last decade, many improvements have been made on these types of detectors, which are now close to their theoretical limit.
However, the ability of a sensor to detect ultra-low concentration does not depend on its limit of detection, but also on the mass transport of the species to the detection zone. Indeed, a biological or chemical specie can be detected only if it reaches the sensing zone of the biosensor. At an ultra-low concentration of target species, a long time may pass until the traget binds to the sensing surface.
To address this problem, chemical or biological species can be trapped close to the detection surface by acting on mass transport. In his Ph.D. work, Q. Avenas showed that mass transport can be activated by creating a force which acts directly on the targets, or by creating a flow dragging targets to the sensing surface. This project follows this work. The objective is to use AC electric fields to create electro-hydrodynamic phenomena favorable to the detection of analytes or micro-objects (such as latex beads used as a model initially), then to optimize the chip design developed to obtain the most efficient trapping. The electrokinetic phenomena involved will be simulated using COMSOL multiphysics software.
Secondly, the designed sensor will be tested for the detection of biological objects such as bacteria in water, water monitoring representing a major public health issue. To selectively capture bacteria, it will be necessary to use surface chemistry that allows a recognition element (an antibody) to be immobilized on the sensitive surface of the sensor. Finally, the response of the sensor as a function of the concentration of bacteria will be characterized.
Key Words : Surface plasmon resonance, dielctrophoresis, electroosmosis, biosensing
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