Conductivity of a suspension of nanowires in a weakly conducting medium

We study the macroscopic electrical conductivity of a composite made of straight or coiled nanowires suspended in a poorly conducting medium. We assume that the volume fraction of the wires is so large that spaces occupied by them overlap, but there is still enough room to distribute the wires isotropically. We found a wealth of scaling regimes at different ratios of conductivities of the wire, σ1, and of the medium, σ2, lengths of wires, and their persistent lengths and volume fractions. There are large ranges of parameters where macroscopic conductivity is proportional to (σ1 σ2) 1 2. These results are directly applicable to the calculation of the macroscopic diffusion constant of nonspecific DNA-binding proteins in semidilute DNA solution.