  We analyze theoretically and by means of molecular dynamics (MD) simulations
the generation of mechanical force by a polyelectrolyte (PE) chain grafted to a
plane. The PE is exposed to an external electric field that favors its
adsorption on the plane. The free end of the chain is linked to a deformable
target body. Varying the field one can alter the length of the non-adsorbed
part of the chain. This entails variation of the deformation of the target body
and hence variation of the arising in the body force. Our theoretical
predictions for the generated force are in a very good agreement with the MD
data. Using the developed theory for the generated force we study the
effectiveness of possible PE-based nano-vices, comprised of two clenching
planes connected by PEs and exposed to an external electric field. We exploit
Cundall-Struck solid friction model to describe the friction between a particle
and the clenching planes. We compute the self-diffusion coefficient of a
clenched particle and show that it drastically decreases even in weak applied
fields. This demonstrates the efficacy of the PE-based nano-vices, which may be
a a possible alternative to the existing nano-tube nano-tweezers and optical
tweezers.
