>Magister Scientiae - MSc / Microfluidic paper based electrochemical sensing devices (μPEDs) provides a new way for point of care testing (POCT). μPEDs offer an inexpensive, portable, easy to use technology too monitor the environment and diagnose diseases, especially in developing countries in cases where there is not enough infrastructure and a limited trained medical and health professionals. The aim of this work is to develop a paper based electrode which can be further integrated into a microfluidic paper device to develop miniature point of care devices. Paper was used as a substrate for printing of the electrode because it is found everywhere, inexpensive and it is compatible with a number of chemical, biochemical and medical applications. Polyamic acid (PAA) was incorporated into commercial carbon ink and was used to print the working electrode. The first part of the study was conducted using the commercial screen printed carbon electrodes (SPCE) to study and understand the electrochemical behaviour of PAA. Cobalt nanoparticles and cobalt nanoparticles‐polyamic acid composites were electrochemically deposited onto SPCE. The modified electrodes were characterised using cyclic voltammetry. As synthesised polyamic acid were characterised using Scanning Electron Microscopy (SEM) to evaluate the morphology and chemical composition of polyamic acid. Transmission Electron Microscopy (TEM) was used to study the particle size and chemical composition of cobalt nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) was used to study the chemical nature of polyamic acid and cyclic voltammetry (CV) was used to study the electrochemical behaviour of polyamic acid and cobalt nanoparticle electrodes. The diffusion coefficients and formal potential of the electrodes were calculated. The modified and bare electrodes were also used to electrochemically detect Norfloxacin in an aqueous solution by CV and square wave voltammetry (SWV) and the analytical performance of the electrochemical systems are reported here. The obtained limit of detection for the bare SPCE was 3.7 x 10‐3 M and 14.7 x 10‐3 M for the PAA‐SPCE.

Capteur électrochimique basé sur des matériaux carbonés fonctionnalisés, pour la détection de deux micropolluants faisant partie des substances prioritaires de la Directive Cadre européenne sur l’Eau (DCE2000/60/CE) : le plomb et l’anthracène. Les capteurs électrochimiques permettent d’atteindre des limites de détection et une sélectivité adéquates pour l’analyse de micropolluants dont les concentrations sont de l’ordredu μg/L, et sont simples d’utilisation pour des analyses in situ à moindre coût comparés aux appareils d’analyses conventionnels. Leur robustesse est un paramètre important afin de permettre des mesures en continu ou semi-continu dans les eaux. Cette thèse propose tout d’abord le développement du capteur pour la détection du plomb. La formulation d’une encre conductrice de carbone est étudiée pour la sérigraphie de ’électrode réceptrice, permettant ainsi de contrôler la composition de l’encre et d’étudier l’influence de la phase carbonée sur les propriétés électrocatalytiques des électrodes. La fonctionnalisation des électrodes par greffage électrochimique d’un sel de diazonium est également étudiée afin de maîtriser la sensibilité et la reproductibilité des électrodes greffées, en contrôlant l’épaisseur et la qualité des couches. Avec cet objectif, la fonctionnalisation dans un liquide ionique protique qui permet le contrôle de la monocouche en modulant la viscosité de ce milieu a été étudiée. Les électrodes greffées montrent des performances analytiques améliorées notamment en termes de répétabilité et de reproductibilité. Enfin ce travail de thèse porte également sur le développement du capteur pour la détection électrochimique de l’anthracène, molécule sans fonctions chimiques. Les électrodes sont, dans ce cas, fonctionnalisées par un polymère à empreinte moléculaire, matériau connu pour sa très grande sélectivité. Les performances de ce capteur, dont la sélectivité est basée uniquement sur le facteur de forme de la molécule, pour la détection de l’anthracène sont alors mises en évidence. / Electrochemical sensor based on functionalized carbon materials, for the detection of two micropollutants, lead and anthracene, which are among of the priority substances of the European Framework Directive on Water(DCE 2000/60 / EC). Electrochemical sensors allow to achieve detection limits and selectivities for the analysis of micropollutants whose concentrations are of the order of μg/L. They are easy to use for in situ analyzes at lower costs compared to those of the conventional analysis equipment. Their robustness is an important parameter in order to allow continuous or semi-continuous measurements in water. First of all, this thesis proposes the development of a sensor for lead detection. The conductive carbon ink formulation is studied for the screen-printing of the receiving electrode, thus allowing to control the ink composition and to study the influence of the carbon phase on the electrocatalytic properties of electrodes. Functionalization of electrodes by electrochemical grafting of a diazonium salt is also studied in order to control the sensitivity and reproducibility of grafted electrodes, by controlling the thickness and the quality of the layers. With this aim it has been studied the functionalization in a protic ionic liquid in order to allow the control of the monolayer bymodulating the viscosity of this medium. The grafted electrodes show improved analytical performance especially in terms of repeatability and reproducibility. Finally, this work reports the development of a sensor for the electrochemical detection of anthracene, a molecule without chemical functions. In this case, a molecularly imprinted polymer, a material known for its very high selectivity, functionalizes the electrodes.Having a selectivity is only based on the form factor of the molecule, the performance of the sensor developed for the detection of anthracene is also highlighted.