Disclosed is a device including at least one circulating zone and at least one fluid including at least one more-paramagnetic liquid and at least one less-paramagnetic liquid forming a liquid-liquid interphase, the device including at least one element generating, in the circulating zone, a magnetic field, wherein the less-paramagnetic liquid is surrounded by the more-paramagnetic liquid in the circulating zone or wherein the more-paramagnetic liquid is surrounded by the less-paramagnetic liquid in the circulating zone. Also disclosed is a method including circulating at least one less-paramagnetic liquid inside one or more circulating zones of a device including at least one circulating zone and at least one more-paramagnetic liquid in the circulating zone.