Michel Cabrera

Towards better DNA chip hybridization using chaotic advection

Numerical studies for two protocols of micromixing based on chaotic advection to improve DNA chip hybridization are presented. The first protocol uses syringes; the other one, pumps. For both protocols, numerical Poincare sections and Lyapunov exponents of the three-dimensional, time-periodic flow are investigated as functions of the period. Model experiments also confirm numerical results. Homogeneity of the dispersion of particles inside the chamber is of primary importance to achieve best chip reliability: although global chaos was obtained for both protocols, we find that the one employing the pumps is more likely to achieve better and more rapid hybridization.

Microphotofabrication of very small objects : Pushing the limits of stereophotolithography

Abstract Stereophotolithography (SPL) allows to manufacture 3D polymer parts directly from Computer Aided Design data files. Its principle is the space resolved polymerization of a resin by a laser. We first discuss the possibilities to make parts with a very high resolution. A first approach was to push the classical SPL process to its limits to get a resolution of about 30 micrometres. A second really innovating one was to modulate the light flux by a liquid crystal display and we obtained a resolution of 5 micrometres. Since the use of these parts is limited by the nature of photopolymers, we also developed a new process to make complex polymer/metal parts directly. It consists in making the part layer by layer by using three techniques: SPL, electrodeposit of copper and laser silver plating.

Modelization and characterization of 2D and 3D mid inductors for multidirectional inductive proximity sensing

The modelization, fabrication and characterization of inductors using Molded Interconnect Device technology for multidirectional inductive proximity sensing is reported. Inductive proximity sensing allows contactless measurement of the position of electrically conductive objects. The principle of measurement relies on the use of an inductor which impedance is modified by the induced eddy currents at the surface of the conductive object. Inductors on LCP polymer are fabricated with MID technology, electroless metallization and electrodeposition of copper. 2D inductors are fabricated and characterized. Key parameter values are analyzed with a simplified model. Then proof of concept for 3D proximity sensing with a MID device is demonstrated.

Viscous Drops Spreading With Evaporation And Applications To DNA Biochips

We develop a lubrication model for the viscous drop spreading with evaporation. It is then solved in the quasi-static case and the numerical method is used in the parameter identification in the application to DNA chips.