Water-mediated ordering of nanoparticles in an electric field

Interfacial polar molecules features a strongly anisotropic response to applied electric field. favoring dipole orientations parallel to the interface. In water, in particular, this effect combines with generic orientational preferences induced by spatial asymmetry of water hydrogen bonding under confined geometry, which may give rise to a Janus interface. The two effects manifest themselves in considerable dependence of water polarization on both the field direction relative to the interface and the polarity (sign) of the field. These torques can align a particle with surface as small as 1nm(2). The mechanism can support electrically controlled ordering of suspended nanoparticles as a means of tuning their propertices and can find application in electro-nanomechanical devices.