Authors:Mohammed Kechadi, Jean Gamby, Lila Chaal, Boualem Saidani and Bernard Tribollet
The present work describes new results using a contact free impedance device, which permits to reach a best understanding of the free contact transduction. Measurements were carried out through a polyethylene terephthalate (PET) microchannel photoablated. Impedance measurement of empty microchannel at different PET thickness separating the two electrodes demonstrate that the recorded impedance is not changed whatever the PET thickness. The result shows that the polyethylene (PE) film lamination has an effect on the impedance measurement in empty microchannel. Then impedances diagrams in the filled microchannel were plotted by subtracting impedance contribution in empty microchannel from the global microdevice response. The Nyquist diagram of filled microchannel exhibits a loop diameter from high to medium frequencies, and a capacitive behavior at low frequencies. The loop diameter obtained is inversely proportional to the microchannel conductivity. Modeling impedance of microsystem highlighted the effect of microchannel rough surface phenomena.
Authors:Mohammed Kechadi, Mathilde Faure, Bruno Sotta and Jean Gamby
The real-time monitoring of the adsorption kinetic of antibody onto polyethylene terephthalate (PET) modified with gold nanoparticles (NPs) is performed into a dielectric flow microchannel. The principle is based on the microelectrode–dielectric interface excitation by a modulated voltage excitation through the dielectric layer with high frequency range. The set-up configuration using a homemade current-to-voltage converter has been developed for fast monitoring of biomolecule adsorption without direct electrical contact of microelectrodes with the microchannel flow. The change in the interfacial admittance, related to the output voltage measured through the microchip, during antibody incubation, gives information on the kinetics involved while antibodies are adsorbed at the interface. An example of adsorption on PET modified with gold NPS was taken. Experimental data were fit with the Langmuir equation and a good correlation was obtained with this latter, where the equilibrium constant, K, was found as 1.55 × 108 M−1 with a limit of detection for antibody concentration without depletion equal to 8.25 nM.