Nonwoven fabrics can contain changes in density that affect quality of the final product. Density can be monitored with a capacitive sensor if the thickness of the material is controlled.
During processing of the fabric, the thickness is either controlled or measured by a secondary process. A capacitive probe looking through the fabric at a reference target will respond to changes in the density of the fabric. The sensor output can alert and operator or be fed back into a servo system to control the process.