Soft capacitor fibers using conductive polymers for electronic textiles

TL;DR

This paper introduces a highly flexible, conductive polymer-based capacitor fiber with high capacitance, fabricated via fiber drawing, suitable for smart textiles and energy storage applications.

Contribution

It presents a novel fiber fabrication method producing high-capacitance, scalable, polymer-based fibers with unique electrical properties for electronic textiles.

Findings

Capacitance of 60-100 nF/m, independent of fiber diameter

Fiber length inversely affects transverse resistance, which is about 5 kOhm/L

Fibers are soft, scalable, and suitable for sensing and energy storage

Abstract

A novel, highly flexible, conductive polymer-based fiber with high electric capacitance is reported. In its crossection the fiber features a periodic sequence of hundreds of conductive and isolating plastic layers positioned around metallic electrodes. The fiber is fabricated using fiber drawing method, where a multi-material macroscopic preform is drawn into a sub-millimeter capacitor fiber in a single fabrication step. Several kilometres of fibers can be obtained from a single preform with fiber diameters ranging between 500um -1000um. A typical measured capacitance of our fibers is 60-100 nF/m and it is independent of the fiber diameter. For comparison, a coaxial cable of the comparable dimensions would have only ~0.06nF/m capacitance. Analysis of the fiber frequency response shows that in its simplest interrogation mode the capacitor fiber has a transverse resistance of 5 kOhm/L, which is inversely proportional to the fiber length L and is independent of the fiber diameter. Softness of the fiber materials, absence of liquid electrolyte in the fiber structure, ease of scalability to large production volumes, and high capacitance of our fibers make them interesting for various smart textile applications ranging from distributed sensing to energy storage.