On the design of capacitive sensors using flexible electrodes for multipurpose measurements
- 1 April 2007
- journal article
- research article
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 78 (4), 043903
- https://doi.org/10.1063/1.2721406
Abstract
This article evaluates the potential of capacitive measurements using flexible electrodes to access various physical quantities. These electrodes are made of a thin metallic film, typical thickness 0.2 μ m , evaporated on a plastic substrate. Their large flexibility enables them to be mounted in complex geometries such as curved surfaces. In the configuration of planar condensers, using a very sensitive commercial capacitive bridge and a three-terminal measurement method, several measurements are presented. A relative resolution of 10 − 8 for the thermal expansion of samples is obtained at low temperature in a differential configuration. The same technique adopted for pressure gauge measurements at low temperature led to a typical 0.1 Pa resolution over a dynamic range of 10 4 Pa . In the configuration of interleaved electrodes,condensers have been used to measure wetting by either bulk liquid helium or by thin continuous heliumfilms in a cylindrical pipe. Both experimental and numerical evidence is provided, showing that the close proximity of a reference ground potential significantly increases the relative sensitivity to fluid wetting. Further, interleaved electrodes can be used to access both the area that is covered by a liquid film but also to determine the thickness of this film, provided it is comparable to the periodicity of the electrode pattern.This publication has 4 references indexed in Scilit:
- Probing the wetted perimeter in a He II two-phase pipe-flow experiment using a capacitive sensorAIP Conference Proceedings, 2002
- Stratified two-phase superfluid helium flow: IICryogenics, 1997
- Silica-aerogel thermal expansion induced by submonolayer helium adsorptionPhysical Review B, 1995
- High-resolution capacitive pressure gaugesReview of Scientific Instruments, 1993