Modelling and evaluation of planar inter digital capacitive structures and SAW devices for sensing applications using finite element methods

Abstract

newlineSensors are omnipresent in all technological gadgets, and the newlineimportance and necessity of sensors have increased with increase in newlineautomation and wireless monitoring of processes. They show up in every newlineaspects of life directly or indirectly. Capacitive sensors have been used newlinefor a wide range of applications due to their technical features and newlineadvantages, such as fast response, low cost, flexibility in electrode design, newlineand nonintrusive. newlineSensors based on Inter-Digital Capacitive (IDC) structures make use newlineof near surface properties for the evaluation of a process. These co-planar newlinecapacitive structures undergo deviations in the electric field distributions newlinewhen they are exposed to external stimuli. Hence the inter-digital capacitive newlinestructures are widely accepted for applications which demand for newlinesensitive and non-destructive testing. Surface Acoustic Wave (SAW) newlinedevices make use of inter-digital structure as electrode for the generation newlineand detection of surface acoustic waves. newlineIn this thesis a numerical modeling and evaluation of inter-digital newlinecapacitive structures with different structural parameters for sensing newlinecapabilities are presented. The method is extended to the analysis of newlineSAW devices as well, where inter-digital structures play a major role. newlineThe Numerical evaluation is carried out with the commercial software newlinetool ANSYS. This software platform is equipped with well-developed newlinesolvers, Graphical User Interface (GUI), and post processing capabilities newlineto perform different analyses. The electrostatic analysis supports the capacitance calculation as well. The coupled field analysis in ANSYS is newlinecapable of solving the interaction between different physical phenomena newlinelike piezoelectric effect, which enables the analysis of SAW devices.