Does anyone know what size-range of metal particles can be driven by either electrical field or magnetic field? For example, should the size be nano-meter range or micrometer?
There is almost no limit to the size of a "particle" that can be moved by a magnetic field. See for example this picture (source)
which shows an entire hospital gurney being sucked into an MRI scanner. In this case the patient was injured but survived. Not all are that lucky.
Bottom line: with a sufficiently strong (and diverging) field, a ferromagnetic "particle" can be very large, and yet be moved.