Critical electrical behaviors of finger-sensing metal/polymer composites near the percolation threshold

In this work, the critical pressure-induced electrical properties of metal/polymer composites were studied systematically. The conductivity and dielectric constant satisfied the scaling electric equations: σAC∝ωx and ε∝ω-y, respectively. The critical exponents x=0.72±0.006 and y=0.32±0.027 agreed with the general relation x+y=1. The results proved that the transport properties of conductive polymer composites under pressure could be ascribed to polarization effects. A striking loss peak appeared in the curve of double logarithmic plot of tanδ vs. pressure, indicating that the formation of current network required maximum amount of electric energy during the increase of uniaxal pressure.