Functionalized magnetoelastic resonant platforms for chemical and biological detection purposes

Résumé

In recent years, research on magnetoelastic materials has focused on their applications as sensors to observe, measure and control different kind of physical, chemical and biological parameters, taking advantage of the remote query and answer of this kind of materials. In order to use those magnetoelastic materials for sensing purposes, they must be coated with an active layer which will be the responsible of selectively detect and trap the target molecule or analyte desired to be detected. This thesis work is devoted to different functionalization processes performed using different active materials as a polymer, ZnO or zeolites onto magnetoelastic materials. Polystyrene depositions allowed studying the main two parameters affecting the detection process, the sensitivity and the quality factor. By following the change on the resonance frequency with the deposited polymer mass it has been probed that the linearity of the detection process can be applied just for small-deposited mass changes.Different methods to form a homogenous ZnO film onto the magnetoelastic material were tried. Finally, ZnO depositions were performed by casting a nanoparticle suspension onto the Metglas materials. This allowed to measure by using the resonance-antiresonance method the Young modulus of the ZnO deposited film. As ZnO is biocompatible and allows protein immobilization, a H2O2 sensor was fabricated by pinning hemoglobin onto the ZnO layer. Hemoglobin reacts with hydrogen peroxide, which plays an important role in some physiological and biological processes. The response of the sensor was followed for first time by using simultaneously two methods, the magnetoelastic resonance method in order to study the evolution of the resonance frequency and by cyclic voltammetry measurements as the reaction between H2O2 and hemoglobin is electrochemical.The third material used to functionalize the resonant platforms were zeolites. Three different zeolites, LTA, FAU and MFI were hydrothermally synthesized onto a homemade magnetoelastic material in order to use those systems as sensor for o-xylene detection.