Embodiments of the invention include a microfluidic device, which comprises a substrate with a channel defined therein, on an upper surface of the substrate, wherein a bottom wall of the channel comprises several contiguous steps having an asymmetric profile along a main direction of the channel, so as to form a ratchet topography. The device further comprises a lid, opposite to and at a distance from the upper surface of the substrate, so as to face the bottom wall of the channel. The bottom wall and the lid are designed to allow like sign charges to accumulate thereat, in presence of a polar liquid confined in the channel between the bottom wall and the lid, so as to allow displacement of nanoscale particles in the polar liquid, along said main direction of the channel, under application of an alternating force to said nanoscale particles, in operation of the device.