More than 100 years after the first use of capacitive sensing principles, capacitive sensors are found in billions of products for various applications. As the actual sensor elements are just (more or less) conductive areas, they are of unparalleled simplicity and they can be realized by a variety of manufacturing technologies and materials. While used to cover rather large spatial areas e.g. in touch screens in mobile phones or as replacement of mechanical switches in cars and home appliances, the principle is also used in miniaturized microelectromechanical devices, e.g. in pressure, force and acceleration sensors or for the detection of chemical substances or biological cells.
As capacitive sensor exhibit sensitivities towards many physical parameters they find wide applicability. However, the sensitivity towards many parameters also implies that cross-sensitivities to may be a major concern. Thus, in order to design robust and accurate sensors, the entire chain starting from the electrode topology over the analog measurement circuitry up to the signal processing algorithms used to determine the parameter of interest from the measured capacitances has to be considered. Consequently, the present talk will provide an overview of this entire chain and specifically address reconstruction algorithms (including Electrical Capacitance Tomography) as well as the design strategies for electrode topologies.