Hysteresis and drift in a carbon-polymer composite strain sensor

摘要

A conductive polymer strain gauge was screen printed to produce an active area of 3mm x 4mm The graphite and titanium dioxide loaded thermoplastic device was found to have a resistance of 4.3kΩ and a gauge factor of up to 20. The higher resistivity and gauge factor result in a lower power consumption and higher sensitivity when directly compared to metal foil strain gauges. However, a substantial hysteresis of approximately 80με was identified in a complete strain cycle from 0με to 730με. The source of this hysteresis was considered to be the thermoplastic matrix. Subsequently the viscoelastic nature of the polymer matrix was analysed using the gauge's resistive signal as it changed under applied strains, and this output was then compared to the standard linear solid (or Zener) model from linear viscoelastic theory. This model was applied to the data and with some limitations was found to make an improvement to the reported hysteresis.