We propose an analytical model for the CMOS Buried Multiple Junction (BMJ) detector exhibiting breakdown voltage shift depending on adjacent junction's bias. The device's singular behavior has been observed when two adjacent junctions are in reach-through (RT) condition. The breakdown current has been identified to be predominated by thermionic emission. The proposed model determines, for a given BMJ structure with uniform or Gaussian doping distributions under bias conditions, whether two adjacent junctions are in RT condition. In this case, it calculates the merged depletion limits, electric field and electrostatic potential profile. The potential barrier height of each merged depletion region can then be extracted and the thermionic current be computed. Model computations have been compared with TCAD simulations and measurements on the BMJ detector. Good agreements have been observed for different structures in different bias conditions at different temperatures.

A novel concept of microfluidic actuator based on a slack metallized film confined between two parallel grid-electrodes separated by a gap is presented. The film is loosely attached such that it can move freely between the two grid-electrodes. Upon voltage application between the metallized film and one grid-electrode, electrostatic attraction tends to press the metallized film on the grid, thus pushing the fluid through the grid. This evolution happens through a film fold travelling across the cell width. Samples using a replication of grid-electrodes manufactured by silicon anisotropic etching have been assembled. An equilibrium theory of operation and an experimental characterization with measurements of exchanged liquid volumes, differential pressures, capacitance and applied voltage are presented, both agreeing within +/- 15%. It will be shown that actuators with an active zone of 8 mm x 45 mm and a gap of 0.25 mm can move 100 mu l against differential pressures of about 200 Pa with a 100 V power supply at 100 Hz consuming few tens of mW. The only moving part is the deformable film and the actuator is silent when filled with liquids. The new concept also supports an accurate capacitance monitoring of the exchanged volumes. The actuation can be reversible by connecting one or the other grid electrode. This new pumping mechanism has been primarily designed for exchanging a given volume of two insulating fluids of different refractive indices, in order to activate ophthalmic variable eyeglasses for presbyopia correction. Nevertheless, the same concept can be extended to continuous flow pumping. (C) 2019 Elsevier B.V. All rights reserved.

We present a simple and inexpensive method for label-free detection of biomolecules. The method monitors the changes in streaming current in a fused silica capillary as target biomolecules bind to immobilized receptors on the inner surface of the capillary. To validate the concept, we show detection and time response of different protein-ligand and protein-protein systems: biotin-avidin and biotin-streptavidin, barstar-dibarnase and Z domain-immunoglobulin G (IgG). We show that specific binding of these biomolecules can be reliably monitored using a very simple setup. Using sequential injections of various proteins at a diverse concentration range and as well as diluted human serum we further investigate the capacity of the proposed technique to perform specific target detection from a complex sample. We also investigate the time for the signal to reach equilibrium and its dependence on analyte concentration and demonstrate that the current setup can be used to detect biomolecules at a concentration as low as 100pM without requiring any advanced device fabrication procedures. Finally, an analytical model based on diffusion theory has been presented to explain the dependence of the saturation time on the analyte concentration and capillary dimensions and how reducing length and inner diameter of the capillary is predicted to give faster detection and in practice also lower limit of detection.

Electrowetting-on-dielectric technology suffers from a lack of accuracy and reliability under DC voltage. The root of this phenomenon is related to charge injection within dielectric materials polarized and in contact with electrolytes. Correlation between contact angle measurements and transient current is used to investigate electrowetting stability under DC voltage. In particular, nature of ionic species and polarization effect are scrutinized. Asymmetric mechanisms appear between positive and negative polarizations from both wetting stability and leakage current, attributed to charge injection and allowing electrets-type actuation. A first occurrence of large amplitude reverse electrowetting is also observed.

In this paper we introduce a low cost rapid prototyping framework for designing Micro-Nano-Micro (MNM) fluidic preconcentration device based on ion concentration polarization (ICP) phenomenon. Xurography-based microchannels are separated by a strip of ion perm-selective Nafion membrane which plays the role of nanofluidic potential barrier for the negatively charged molecules. As a result, by using this rapid and inexpensive fabrication technique, it is possible to get preconcentration plugs as high as 5000 fold with an original symmetric electroosmotic flow (EOF) condition. Due to its simplicity and performance, this device could be implemented in various bioanalysis systems.

This paper highlights that combining laser interference lithography and electrochemical etching is a cost-effective, efficient method to realize periodic nanopore arrays in silicon with lattice pitch as small as 300 nm on centimeter-scale substrates. The fabrication of wide-area and high aspect ratio 2D pore arrays with 250 nm diameter and 5 μm depth is demonstrated. All the steps of the process have been optimized to achieve vertical sidewalls with 50 nm thickness, providing pore arrays with aspect ratio of 100 on n-type silicon substrates over an area of 2 × 2 cm2. These results constitute a technological advance in the realization of ordered pore arrays in silicon with very small lattice parameters, with impact in biotechnology, energy harvesting, or sensors.

We present an experimental study on the electrofluidic transistor in this paper. A novel and easy way to integrate the transistor into a microchannel is developed. The performances of the insulating layer, especially the leakage current under gate voltage, are carefully characterized. The change of surface charge on silica surface by gate polarization is measured, however, by measuring the streaming current, the gating effect on zeta potential has not been observed. This result should imply new assumption in the understanding of the charge regulation in the electrical double layer under gate polarization.

Mixing of analytes and reagents is a critical step in Lab-on-Chip or Micro-Total Analysis Systems (mu TAS) due to a laminar behaviour of flows. In this work, we propose a new approach to achieve efficient mixing, which is based on the perturbation of the laminar flow via electrokinetic control of the liquid/liquid interface. High voltage periodic pulses are used to generate a larger interface between two liquids, resulting in an increase of mixing efficiency by diffusion. The advantage of this mixing method is that it does not require (i) any pump, (ii) any zeta potential modification of the surface and (iii) any supplementary high voltage compared to a simple mixing approach only based on diffusion.

Reducing the friction of liquid flows on solid surfaces has become an important issue with the development of microfluidics systems, and more generally for the manipulation of fluids at small scales. To achieve high slippage of liquids at walls, the use of gas as a lubricant1,2,3,4—such as microbubbles trapped in superhydrophobic surfaces5—has been suggested. The effect of microbubbles on the effective boundary condition has been investigated in a number of theoretical studies6,7,8,9, which basically show that on flat composite interfaces the magnitude of the slippage is proportional to the periodicity of the gaseous patterns10. Recent experiments aiming to probe the effective boundary condition on superhydrophobic surfaces with trapped bubbles have indeed shown high slippage in agreement with these theoretical predictions10,11,12. Here, we report nanorheology measurements of the boundary flow on a surface with calibrated microbubbles. We show that gas trapped at a solid surface can also act as an anti-lubricant and promote high friction. The liquid–gas menisci have a dramatic influence on the boundary condition, and can turn it from slippery to sticky. It is therefore essential to integrate the control of menisci in fluidic microsystems designed to reduce wall friction.

Electrochemical etching may be used to form high aspect-ratio pores and pillars in silicon. Starting from lithographically patterned surfaces, regular arrays of macro pores or pillars can be fabricated. The pitch and pillar) pore size must then scale with the depletion width, in turn set by the material resistivity. We review various results where the achievable pore diameter ranges from 100 mu m for high resistivity material to the submicron range for highly doped wafers. At slightly higher current density and using different patterns, pillars or walls may be formed. The fabricated structures may be further processed and we demonstrate oxidation, uniform wall doping and finally, filling of the structures to result in functional materials. Applications include both optical, microelectronic, material and bio-applications.

The surface charge of a microfluid system is a very important experimental factor because the electroosmatic flow (and the seperation efficiency) depends directly on it. So, the characterization of this parameter is very interesting. Some measurement methods of this surface charge already exist, but take generally a long time to be exploited. A more original method, by measurements of current of flow is used here. The material which has here interested us us the PDMS, polymer largely used into microfluidic today. The surface charge of the PDMS was measured according to two important parameters: the relaxation time of the surface after plasma O-2 oxidation, and the pH of the electrolyte filling the microchannels.

Une des promesses les plus attrayantes de la microfluidique est la réalisation de « Lab-on-chip », dispositifs permettant de regrouper sur une seule puce l’ensemble des fonctions d’un laboratoire de chimie analytique conventionnel : le mélange, la préconcentration, la séparation, la quantification, le stockage, etc. Ainsi, à terme, les analyses deviendront portables, plus rapides, moins chères et plus flexibles. Cet article présente la réalisation d’un microsystème permettant dans un premier temps la séparation et la détection de molécules biologique en solution. Il y est présenté la méthode de séparation mise en œuvre ici, la fabrication de cette puce, la détection des molécules séparées, ainsi que les premiers résultats obtenus.

Silicon nanopillars, formed by electron beam lithography, were electrochemically etched to provide controlled size reduction. The smallest dimensions achieved were pillars of 15 nm in diameter, restricted mainly by the scanning electron microscope used for characterization. The etch rate was mainly determined by the photogeneration of carriers, by the HF concentration and by the applied voltage bias. The applied bias also controlled the resulting shape of the pillars such that a high bias resulted in etching of the pillar top whereas a negative bias caused etching only at the pillar base. For 0 V, a relatively conform etching of the pillar was observed. We discuss these phenomena in terms of electropolishing or pore formation effects on a local scale.