Broadband Dielectric Characterization Of Flexible Substrates Using Organic Conductive Polymer Microstrip Lines

The interest from both consumers and industry toward flexible and organic electronics has grown enormously due to the unique properties of the materials used (flexible, stretchable, reconfigurable, and not easily breakable). In radio frequency and electronic organic systems fabrication, one important feature is the substrate complex dielectric constant. Particularly, in the context of the development of printed organic electronics technology, one of the major challenges is the knowledge of the effect on substrates complex dielectric constant retrieval when using organic conductive materials instead of classical metals (gold, copper, etc). Indeed, the precision on the determination of this parameter depends also on the characteristics of the conductive material used for the characterization of the substrate. When looking to full polymer devices, it is important to evaluate the precision on the determination of the parameters of interest without using metallic structures for the tests. This paper presents the characterization of a substrate on which a conductive polymer, polyaniline (PANI) doped with multiwall carbon nanotubes (MWCNTs) is deposited. The characterization technique is based on the well-known 2 microstrip lines method. The microstrip lines, fabricated from PANI/MWCNTs, are processed on a substrate made of Kapton, which is a good candidate for flexible electronics. The extraction of the complex dielectric constant is made on the frequency range (1-8 GHz).