  Above a certain density threshold, suspensions of rod-like colloidal
particles form system-spanning networks. Using Monte Carlo simulations, we
investigate how the depletion forces caused by spherical particles affect these
networks in isotropic suspensions of rods. Although the depletion forces are
strongly anisotropic and favor alignment of the rods, the percolation threshold
of the rods decreases significantly. The relative size of the effect increases
with the aspect ratio of the rods. The structural changes induced in the
suspension by the depletant are characterized in detail and the system is
compared to an ideal fluid of freely interpenetrable rods.
