FEM-assisted design of multi-purpose printed-circuit sensor structures

Abstract:
In this paper the finite element method assisted development of a novel type of planar sensor structures for measurement of multiphysical parameters is presented. The sensor structures are printed circuit boards (PCB) which are shaped in a way that their electrical characteristics change significantly under the influence of temperature and humidity. It is shown, how different PCB layouts and their main effects on the sensor sensitivity can be evaluated with a combination of analytical estimation and finite element method (FEM) simulation models with the FEM-Software Ansys Maxwell. The simulation results are experimentally validated on the basis of test samples. Three different types of PCB with different base materials are used for the validation. Rigid PCBs made with the standard glass-reinforced fire resistant epoxy resin (known as FR4), flexible PCBs made from polyimide (PI) and stretchable PCBs made from thermoplastic polyurethane (TPU).