  In the Nernst-Planck equations in two or more dimensions, a non-Faradaic
electric current can arise as a consequence of connecting patches with
different liquid junction potentials. Whereas this current vanishes for binary
electrolytes or one-dimensional problems, it is in general non-vanishing for
example in crossed salt gradients. For a suspended colloidal particle,
electrophoresis in the corresponding electrostatic potential gradient is
generally vectorially misaligned with chemiphoresis in the concentration
gradients, and diffusiophoresis (via electrophoresis) can occur in regions
where there are no local concentration gradients ('action at a distance').
These phenomena may provide new opportunities to manipulate and sort particles,
in microfluidic devices for example.
