Measurement of the gauge factor of carbon fiber and its application to sensors

The electrical properties of carbon fiber (CF), an attractive material for strain gauges that can also be applied to resonating sensors, are reported in this paper. The CFs were manufactured from polyactylonitrile (PAN). The fabricated CFs had a 10 μm diameter and a length of several cm. The electrical resistivity of the CFs was found to be about 3 × 10−3 Ω cm. The gauge factor of the CF was also observed, and it was found to be about 100–400, depending on the structure of the CF. For the resonating sensor applications of the CF, it was selectively placed in the gaps between the Al electrodes through dielectrophoresis. When the CF was resonated at the 5th resonance mode, a large change of its resistance was observed through an electrical system. The results of the experiment were found to coincide with the calculation results.