RF sensors for microscopic dielectric analysis of solutions and particles : Application to cell biochips ; Capteurs RF pour la caractérisation diélectrique de solutions et de particules à l'échelle micrométrique : Application aux biopuces à cellules

The proposed work deals with the development and characterization of label-free microfluidic biosensors dedicated to the microwave dielectric spectroscopy of small volumes (few nL) and flowing micro-scale particles (about tens of µm). Microwave dielectric spectroscopy offers unique capabilities to investigate intracellular properties of biological cells, which are informative on many biological processes. The sensing principle is based on a capacitive detection which present the main advantage to able achieving broadband analysis (typically 400 MHz to 8 GHz in this work). Thick gold metal electrodes have been investigated to perform high sensitive analysis ensuring a homogeneous electric field in the detection area. A microfluidic system has been implemented over the RF circuit so that flowing liquid minimally impacts global losses of the system and has hence a limited effect on sensor sensitivity. After a calibration step, the detection and analysis capabilities of the proposed microfluidic sensors have been demonstrated on different solutions. The real part of their relative permittivity has been extracted and compared both to literature and measurements achieved with a commercial coaxial probe. Then, the feasibility of using such broadband sensors to analyze flowing micro-particles in the microfluidic channels has been studied. After electromagnetic simulations, experiments have allowed measuring capacitance contrasts around 1 fF at 5 GHz which is highly competitive with the current state-of-the-art. Finally, preliminary experimentations have been achieved on cancerous cells. The presented results demonstrate the high potential of the proposed approach to develop new label-free analysis tools with a large application range, either in the diagnosis or treatment fields. ; Les travaux de thèse proposés concernent le développement et la caractérisation de biocapteurs microfluidiques dédiés à la spectroscopie diélectrique microondes sur de petits volumes de liquides (quelques nL) et des particules micrométriques ...