Pascal Colpo

Determination of the equivalent circuit of inductively coupled plasma sources

This article presents a new approach to investigate and model the electrical characteristics of inductive plasma sources. The technique is primarily based on the measurement of the total complex impedance of the plasma source. The measurements are subsequently numerically fitted to a generic and qualitative electrical model, predetermined by a classical Bode analysis of a circuit including a conductive dummy load of size comparable to the plasma itself. The match between the modeling and the experimental data using this new approach shows a drastic improvement compared to the usual inductively coupled plasma (ICP) electrical model, which is also detailed here as a comparison. We conclude the article on prospective benefits of an accurate electrical model for ICP plasma sources, showing in particular that the global electrical parameters of the discharge can be correlated with a good level of accuracy to the local electrical parameters of the plasma. Beyond the technological necessity to better understand ...

Electrical modeling of HF coupled inductors supplying a double frequency inductive plasma reactor

A new inductive plasma reactor has been developed for metal coating. It combines magnetic plasma generation at 13.56 MHz and induction heating at 100 kHz. The unavoidable coupling of the two coaxial coils allows one electrical generator to force power in the other, compromising the reliability of the system, except if rejecting filters are inserted. Therefore, an equivalent circuit of the double coil set is needed to specify and design the necessary filters. The aim of this paper is to present and justify the electrical representation of this very special high frequency transformer which have been used successfully.

Electrical modelling of RF coupled inductors supplying a double frequency inductive plasma reactor

A new inductive plasma reactor has been developed for thin-film depositions using the plasma enhanced chemical vapour deposition (PECVD) process. This apparatus combines an inductive plasma generation at 13.56 MHz, plus a direct heating of the substrate by a supplementary inductive set-up at 100 kHz. The unavoidable coupling of the two coaxial coils allows one electrical generator to force power in the other, compromising the reliability of the system, unless rejecting filters are inserted. Therefore, an equivalent circuit of the double-coil set is needed to specify and design the necessary filters. The aim of this paper is to present and justify the electrical representation of this very special, high-frequency transformer which has been used successfully.

Direct quantification of nanoparticle surface hydrophobicity

Hydrophobicity is an important parameter for the risk assessment of chemicals, but standardised quantitative methods for the determination of hydrophobicity cannot be applied to nanomaterials. Here we describe a method for the direct quantification of the surface energy and hydrophobicity of nanomaterials. The quantification is obtained by comparing the nanomaterial binding affinity to two or more engineered collectors, i.e. surfaces with tuned hydrophobicity. In order to validate the concept, the method is applied to a set of nanoparticles with varying degrees of hydrophobicity. The technique described represents an alternative to the use of other methods such as hydrophobic interaction chromatography or water–octanol partition, which provide only qualitative values of hydrophobicity.The hydrophobicity of nanomaterials can strongly influence their behaviour and particularly their interaction with biological systems, but quantifying this in solution can be difficult. Here the surface hydrophobicity of nanoparticles in solution is quantitatively measured by analysing the kinetics of binding to engineered collectors.

A 2D nanoparticle sorter: towards an on-chip quantification and full characterization of nanoparticles

In the context of the extensive use of engineered nanomaterials (ENMs) in consumer products, industrial applications and nanomedicine, there is an important need of new methods for an exhaustive characterization of their physicochemical properties. Among them, surface hydrophobicity is considered as a key factor to be controlled, in particular for nanomedicine applications1,2. The proposed study demonstrates the proof-of-concept of an inexpensive characterization process, enabling the sorting of ENMs according to their hydrophobicity and surface charge, together with the classical characterization of size and shape. The detection platform is based on the use of a surface modified through plasma polymer and layer-by-layer polyelectrolyte deposition in order to generate areas of tuned surface properties to bind ENMs selectively by hydrophobic forces and electrostatic interactions. The key advantages of such a device is the decrease of time and assay costs thanks to the all-in-one characterization process and the multiplexing that could replace the use of different methods and expensive equipment to give equivalent results. In this way, the full characterization of NP could be expanded in all the areas covering NP-related applications.

Modeling of the Equivalent Circuit of Inductively Coupled Plasma Sources

This paper presents a method to determine the equivalent circuit of an Inductively Coupled Plasma source (ICP), in relating impedance measurements to numerical simulation.