Review of Progress in Quantitative Nondestructive Evaluation
This paper describes the design of two circular coplanar interdigital sensors with i) a spiral interdigital configuration and ii) a concentric interdigital configuration for the nondestructive evaluation of multilayered dielectric structures. A numerical model accounting for sensor geometry, test-piece geometry and real permittivity, and metal electrode thickness has been developed to calculate the capacitance of the sensors when in contact with a planar test-piece comprising up to four layers. Compared with a disk-and-ring coplanar capacitive sensor developed previously, the interdigital configurations are predicted to have higher signal-to-noise ratio and better accuracy in materials characterization. The disk-and-ring configuration, on the other hand, possesses advantages such as deeper penetration depth and better immunity to lift-off variations.
American Institute of Physics
Chen, Tianming and Bowler, Nicola, "Design of interdigital spiral and concentric capacitive sensors for materials evaluation" (2012). Center for Nondestructive Evaluation Conference Papers, Posters and Presentations. 15.