Temperature-dependent electrical resistivity of macroscopic graphene nanoplatelets strips.

This paper studies the temperature-dependence of the electrical resistivity of low-cost commercial graphene-based strips, made by a mixture of epoxy and graphene nanoplatelets. An equivalent homogenous resistivity model is derived from the joint use of experimental data and of simulation results obtained by means of a full-3D numerical electrothermal model. Three different types of macroscopic strips (with surface dimensions of cm2) have been analyzed, differing in the percentage of graphene nanoplatelets. The experimental results show a linear trend of the resistivity in a wide temperature range (-60, +60) °C, and a negative temperature coefficient (NTC materials). The derived analytical model of the temperature-dependent resistivity follows the simple law commonly adopted for conventional conducting materials, such us copper. The model is then validated by using the graphene strips as heating elements, by exploiting Joule effect. These results suggest using such materials as thermristors, in sensing or heating applications.