Single carbon fiber transverse electrical resistivity measurement via the van der Pauw method

Abstract

Although the electrical properties of carbon fibers and carbon fiber composites are critical to the design of composite materials, a direct measurement of the transverse electrical resistivity of a single carbon fiber has not yet been reported. Significant challenges arise in fabricating specimens and making electrical resistance measurements due to the geometry and small diameter of a single carbon fiber (about 4-7 μm). In this study, we report a specimen design and fabrication technique for measuring the transverse electrical resistance of an individual carbon fiber by the van der Pauw method. IM7 carbon fiber specimens are fabricated by a combination of photolithography and the focused ion beam. Specimen thickness, which is required for resistivity calculations, is measured by atomic force microscopy. We measure mean transverse electrical resistivity of (9.3 ± 0.3) × 10−5 Ω m, which is roughly six times greater than the reported longitudinal values. Our measurement technique can be applied to a range of conductive fibers. More accurate measurements of the electrical conduction in carbon fibers are critical for applications such as electromagnetic interference shielding, structural health monitoring, and lightning strike protection.