Analytical capacitive sensor sensitivity distribution and applications

Abstract

Robustness, versatility, high level of performance and low cost are some of the characteristics that make capacitive sensors well suited for industrial applications. They consist only in electrodes and measurement circuits but give access to position information and/or material properties. The design of capacitive sensors is however not so obvious so that simple structures are generally used to avoid time-consuming calculations and developments. We propose an analytical method to determine the sensitivity distribution of any capacitive sensor structure. This method makes it possible to rapidly optimize structures in order to increase the sensor sensitivity to one parameter or to render it less sensitive to another. Comparisons between the sensitivity map of known sensors and those obtained with the analytical method proposed in this paper show a great accordance.

One or two circular shapes? A binary detection for electrical capacitance tomography sensors

“…At this point, one may think of refining the criterion to obtain better result. Indeed the known sensitivity map of the kind of sensors [8] along with this analysis of the "fail" cases yields new hints and ideas. By doing so, better results can indeed be obtained but it consist in blind try and test work.…”

“…This would be equivalent to shifting right of left the electrodes as in a logical register but in a continuous way and performing a measurement each time. The maximal value would be indeed be obtained in most cases depending of the relative circular shape radius and electrode sizes when there is an electrode in front of the circular shape [8]. In that case, the plot is no longer flat but presents a maximal value and the interpolated curve should be symmetrical considering both sides of its maximal value.…”

“…It is founded upon the principles of electrostatic [6,7,8,9,10,11]. Typically, an ECT sensor can yield information on the spatial configuration of a non-conducting material whose permittivity is different from that of the environment.…”

Design and FEM analysis of multi segment capacitive level sensor based on local and global E-fields)

“…For material characterization, capacitive sensing technique is the most frequently used approach due to its robustness and low cost [6][7]. Based on application requirement and measurement scenario, the capacitive sensing element may compose of single electrode [8] or segmented electrodes in various complex structures [9][10].…”

Negative measurement sensitivity values of planar capacitive imaging probes

“…An extensive literature review shows that, the measurement sensitivity distribution of capacitive sensors has been regularly studied for electrical capacitance tomography (ECT) sensor [11,12], for which the knowledge of the sensitivity distribution is the key for image reconstruction [13,14]. However, only sporadic studies on the measurement sensitivity distribution on coplanar capacitive sensors can be found in literature [15] and it has not been systematically discussed.…”