Simulation of Micro-Electronic FlowFET Systems

A microelectronic fluidic system has been investigated by modeling and 3D simulation of fluid flow controlled by an applied gate voltage. The simulations have helped to characterize a novel FlowFET (a fluidic Field Effect Transistor) device under fault-free conditions. The FlowFET operates by applying a voltage field from a gate electrode in the insulated side wall of a microchannel to modulate the ␣-potential at the shear plane [1]. The change in ␣-potential can be used to control both the magnitude and direction of the electroosmotic flow in the microchannel

Modeling of Micro-Electronic Fluidic Systems

A microelectronic fluidic system is studied using modeling and simulation of fluid flow controlled by applying gate voltage. 2D simulations were used to characterize the fluidic Field Effect Transistor (FlowFET) device under fault-free conditions. The FlowFET operates by applying a voltage from a gate electrode in the insulated side wall of a microchannel, to modulate the z-potential at the shear plane. The change in z-potential can be used to control both the magnitude and the direction of the electroosmotic flow in the microchannel

Field effect control of electro-osmotic flow in microfluidic networks

This thesis describes the development of a Field Effect Flow Control (FEFC) system for the control of Electro Osmotic Flow (EOF) in microfluidic networks. For this several aspects of FEFC have been reviewed and a process to fabricate microfluidic channels with integrated electrodes has been developed

The treatment of helicobacter pylori infection and its sequelae with emphasis on nitroimidazole resistance

In this thesis two different aspects of the treament of Helicobacter pylori (H. pylori) infection are described. The first part (chapters 2-8) explores the epidemiology, mechanism, and clinical significance of nitroimidazole resistance as well as the problems encountered in susceptibility testing for nitroimidazoles. ln the second part (chapters 9 -11) three studies concerning the short and long term sequelae of the treatment of this infection are described.... Zie: Summary

Field-effect based attomole titrations in nanoconfinement

This paper describes a novel capacitive method to change the pH in micro- and nanofluidic channels. A device with two metal gate electrodes outside an insulating channel wall is used for this purpose. The device is operated at high ionic strength with thin double layers. We demonstrate that gate potentials applied between the electrodes cause a release or uptake of protons from the silicon nitride surface groups, resulting in a pH shift in the channel and a titration of solution compounds present. Due to the high quality silicon nitride insulating layer, the effect is purely capacitive and electrolysis can be neglected. Fluorescein was employed as a fluorescent pH indicator to quantify the induced pH changes, and a maximum change of 1.6 pH units was calculated. A linear relationship was found between applied potential and fluorescein intensity change, indicating a linear relation between actuated proton amount and applied voltage. Since this pH actuation method avoids redox reactions and can be operated at physiological ionic strength, it can be very useful as a soft way to change the pH in very small volumes e.g. in bioassays or cell-based research. The sensitivity of the optical detection method poses the only limit to the detectable amount of substance and the observed volume. In a preliminary measurement we show one possible application, namely titration of 100 attomol of TRIS in a 7 pL detection volume. It is important to stress that this pH actuation principle fundamentally differs from the pH changes occurring in ionic transistors which are due to counterion enrichment and coion exclusion, because it does not rely on double-layer overlap. As a result it can be operated at high ionic strength and in channels of up to at least 1 µm height