By Anders Guldahl
Sensing is all about the ability to detect or measure changes in physical properties. In the context of an electronic control system, the requirement is to translate a parameter such as temperature, pressure or movement into an electrical signal. While some sensors directly produce a voltage output, which provides the ideal input for a microcontroller-based system, the majority of sensors depend on resistive, inductive or capacitive circuit elements whose behavior varies according to a known characteristic. These sensors typically require an external circuit to convert their output into a measurable signal for capture by a microcontroller (MCU).
Capacitive sensing is all about the ability to measure the capacitance, or more often the change in capacitance, between two or more electrodes. As a technique it is frequently employed to detect proximity or position but can also be used to measure humidity, fluid level and acceleration. Because capacitive sensing supports such a diverse range of applications, solutions are found in many different markets — from industrial, automotive and medical through to consumer. And as more and more electronic products are being designed with touchpads and touchscreens we are seeing an explosion in the use of capacitive sensing technology to provide the vital human machine interface (HMI).