Capacitive proximity sensors detect nearly all materials (both metal and non-metal objects) and can even sense through wood or plastic. This is due to the technology being activated by the dielectric constant of a material. If the target material’s dielectric constant is significantly higher than another material, often wood or plastic, a capacitive sensor can ignore the lower dielectric material and still detect the target material. This unique functionality allows capacitive sensors to detect fill levels of liquids, pellets, and powders through container walls.