of the Diploma Thesis In this Diploma Thesis, the electrochemical behavior of 4-nitrophenol (4-NP) was studied at a newly prepared large-surface carbon film electrode (ls-CFE) using techniques of DC voltammetry (DCV) and differential pulse voltammetry (DPV) with the aim to develop sensitive analytical methods for its determination. Voltammetric behavior of 4-NP was investigated in the region of anodic potentials, in dependence on the pH of the medium used (realized using Britton-Robinson buffer). The optimum pH values for the determination of 4-NP were chosen as follows: pH 3.0 (for DCV) and pH 7.0 (for DPV). During anodic oxidation of 4-NP on the ls-CFE at the concentration of the analyte of 1·10-4 mol/l, the passivation of the electrode surface occurred. Thus, it was decided to record series of measurements always at a new carbon film. Using the sample of 4-NP (at the concentration of 1·10-4 mol/l), the repeatability of the application of individual carbon films was tested, with obtained RSD values of 3.7% and 3.6% for DCV and DPV, respectively. Under optimum conditions, the calibration dependences of 4-NP were measured in the concentration range from 1·10-6 to 1·10-4 mol/l, with the limits of quantification (LQs) of 1.5·10-6 mol/l (for DCV at the ls-CFE) and 4.6·10-7 mol/l (for DPV at the...

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Presented Diploma Thesis is focused on the development, characterization, and utilization of simple and inexpensive electrochemical DNA biosensor for the detection of DNA damage caused by oxidative stress. The initial part of the work is devoted to preparation and characterization of a large-surface carbon film electrode (ls-CFE) modified with carbon nanotubes (CNT/ls-CFE). Carbon nanotubes improve electrochemical properties of the transducer and increase the amount of adsorbed DNA on the electrode surface. Testing of the electrode surface modified with multiwalled carbon nanotubes (MWCNT) was performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using a redox system [Fe(CN)6]4-/3- and using square wave voltammetry without any redox indicator. Carbon nanotubes have proved to be unsuitable material for our type of biosensor, but it can be used inanalytical chemistry for the determination of electroactive substances. The second part of this Thesis deals with the application of the prepared DNA biosensor for the detection of DNA damage by oxidative stress. The biosensor based on the ls-CFE was chosen for this purpose, having several advantages, such as its fast preparation, a simple mechanical renewal of the electrode surface, a good reproducibility of measurements,...

L’avènement des interfaces tactiles ouvre des perspectives d’enrichissement de l’interaction entre l’homme et la machine. Nous proposons un nouveau concept de surfaces tactiles souples dont l’objectif est d’étudier l’interaction entre le signal électrique et l’environnement résistif et diélectrique du support, afin de réaliser le système d’acquisition fournissant une information exploitable par la machine.La base technologique est un guide d’ondes sur substrat souple sur lequel le toucher crée une réflexion au port d’entrée. Nous avons développé une méthode de localisation alternative à la réflectométrie temporelle, nommée Harmonic Detection and Location (HDL), permettant l’utilisation d’une électronique d’acquisition de faible complexité, en bande étroite, autour de 100 MHz. Le concept a été validé à partir de mesures sur des dalles tactiles souples et rigides connectées à un analyseur de réseau, utilisé comme référence. Un système d’acquisition compact basé sur un pont de Wheatstone associé à un détecteur de phase a été développé. Pour ce faire, un travail de caractérisation et d’identification des sources d’erreurs a été mené sur les interactions électromagnétiques entre le doigt et le guide d’onde, les imperfections du guide d’onde et la nature du substrat ainsi que l’impact des erreurs induites par l’électronique d’acquisition.Cette connaissance a permis de co-développer la partie matérielle et l’algorithme de détection pour démontrer une précision de localisation de 2cm. Les fondamentaux posés dans ce travail ouvrent la possibilité de réalisation d’interfaces de grande surface, avec une connectique simple, conformables sur des objets sensitifs en trois dimensions / The advent of sensitive interfaces is promising prospects to the human-machine interaction. We propose a new concept of sensitive flexible surface. Its aim is to study the interaction between electrical signal and resistive and dielectric environment of the support in order to realize an acquisition system providing machine readable information.The technological base is a waveguide on flexible substrate on which the touch creates a reflection at the input port. We have developed a location method as an alternative to the time domain reflectometry (TDR). It is named Harmonic Detection and Location (HDL) and it allows using a narrow band, around 100 MHz, low complexity acquisition system. The concept has been approved using measures on flexible and rigid sensitive surfaces connected to a vector network analyzer (VNA) used as reference. A compact acquisition system based on a Wheatstone bridge associated to a phase detector has been developed. For this purpose, errors characterization and identification work has been done. Electromagnetic interactions between the finger and the waveguide, waveguide imperfections, substrate nature and acquisition system errors’ impact have been studied. This knowledge has provided the possibility to co-develop the hardware and the detection algorithm to demonstrate a location accuracy of 2cm. Fundamental principles of this work provide the possibility of realizing large surface interfaces, with simple connection and conformable, for 3D sensitive objects.