Dr. Xavier Lefévre
CSEM SA, Nanoscale Technology


Porous layers for environmental electrochemical sensors development


Xavier Lefèvre received his MSc from University of Montréal in 2009 after graduating from ESPCI Paris in 2008. He received his PhD in 2012 from Ecole Polytechnique in France where he developed protective and insulating coatings for germanium based on newly designed organic push-pull molecules. During his Postdoc at University of Geneva, he developed new supramolecular compounds for encapsulation. He then worked for Saint-Gobain Research Paris on organic-inorganic interactions and coatings for construction materials. Since 2020, he is working at CSEM as Senior R&D engineer leading projects related to sensing.


Molecularly imprinted polymers are of great interest for environmental applications as they are able to specifically bind contaminants molecules even at very low concentrations. They are thus often used to concentrate the analytes and make them detectable for standard chromatography coupled with mass spectroscopy detection techniques when direct quantification would be impossible. Sensing through MIPs has been a tremendous topic in literature over the past years since they are highly specific, sensitive at low concentrations and robust. Moreover, being rather cheap and simple to use, interest in integrating them in low-cost easy-to-use sensors is growing fast. Complementary to MIPs which are very powerful to detect single molecules, Metal-organic frameworks (MOFs) are hybrid crystalline materials containing organic ligands and metal ions and able to sense families of compounds. Exhibiting high porosity and high surface area, MOFs can be customized to absorb efficiently the targeted analytes. MOFs properties can be well designed and controlled by modulating the metal ions, organic ligands, and the structural characteristics. Especially, the features of pores containing functional groups can allow the selective capture of the target analyte in their confined areas via molecular interactions such as a hydrogen bonding, coordination bond, and ?-? interaction. This results in the pre-concentration effect and improves the sensitivity of detection. Interest in integrating such porous materials as selective adsorbent layers in chemical sensors has increased recently. Nevertheless, in both cases, refinement of sensing materials and transducer mechanisms is still essential to increase the reliability, selectivity, and response kinetics to a level suitable for commercial applications. The KDT Project AGRARSENSE aims at further developing such sensing layers for environmental applications mainly related to water contamination. The sensing layers will be deposited on miniaturized electrodes to monitor the quantity of emerging pollutants in ground or surface waters. Integration of these layers on typical transducers like MEMS or ISFET will also be addressed.

The presented work will give insight on both development of the sensing layers including performances in lab configuration and advanced thin-film deposition techniques to form the sensing layer on the transducer. Formulation aspects as well as key points for the layer properties will be discussed. First results in environmental sensing will also be presented as well as miniaturization attempts.