Performance of the 100-μm Diameter High Conductivity CNT Fibers in MHz Frequencies

In the last few years there is an encouraging development in CNT-based wires. However, not a lot of fabrication technologies are able to produce a promising conductivity value. One of the most highly productive fabrication technologies to increase the electrical characteristics is the solution spinning technology. There are two kinds of high conductivity CNT-wires; one is CNTF yarn and the other is CNT fiber. This paper compares these two kinds of wires in high frequency MHz region. The CNTF yarn is proven to exhibit non-metallic characteristics and has excellent high frequency performance as compared to metals. The main focus of this paper is to investigate the high frequency performance focusing on the CNT fiber. One of the most conductive CNTF-yarn based wires is 500 μm in diameter with a conductivity of 2.7 ± 0.3 MS/m. Whereas, the CNT-fiber based wire is 100 μm in diameter with a conductivity of 8 ± 2 MS/m. Both wires are compared to solid copper wires. A bundle of these CNT fibers has been constructed to form the diameter similar to the other wires. Then, a spiral inductor was made for every wire with the same dimensions. The frequency and temperature measurement results prove that the CNTF yarn performs better than the bundled CNT fiber in high frequency. FEM analysis has been conducted to verify the measurement results. The analysis validated the measurement results and revealed that the CNT fiber displays quasi-metallic characteristics along with anisotropic effects. Both the measurement and the FEM results are discussed in the paper.