  We study theoretically and by means of molecular dynamics (MD) simulations
the generation of mechanical force by grafted polyelectrolytes in an external
electric field, which favors its adsorption on the grafting plane. The force
arises in deformable bodies linked to the free end of the chain. Varying the
field, one controls the length of the non-adsorbed part of the chain and hence
the deformation of the target body, i.e., the arising force too. We consider
target bodies with a linear force-deformation relation and with a Hertzian one.
While the first relation models a coiled Gaussian chain, the second one
describes the force response of a squeezed colloidal particle. The theoretical
dependencies of generated force and compression of the target body on applied
field agree very well with the results of MD simulations. The analyzed
phenomenon may play an important role in a future nano-machinery, e.g. it may
be used to design nano-vices to fix nano-sized objects.
