Capacitive displacement sensors are often used in assembly line testing. Sometimes they are used to test assembled parts for [[uniformity]], thickness or other design features. At other times, they are used to simply look for the presence or absence of a certain component, such as [[glue]].<ref name="LionGlue">[http://www.lionprecision.com/tech-library/appnotes/app-flash/f-cap-0040-glue.html Sensing Glue on Paper], A tutorial on using capacitive sensors for glue sensing.</ref> Using capacitive sensors to test assembly line parts can help to prevent quality concerns further along in the production process.
==Comparison to eddy current displacement sensors==
