A microfluidic system , comprising: a microchannel ; and a sensor system for sensing flow of fluid in said microchannel , the sensor system comprising: a permselective medium positioned to contact the fluid in the microchannel ; a power source ; an arrangement of electrodes , connectable to said power source and arranged to generate an electric field across said permselective medium thereby forming, via the concentration polarization effect, enriched ionic and depleted ionic concentrations in said microchannel near respective opposite ends of said permselective medium , and to generate sensing signals indicative of patterns of said ion concentration that are effected by the flow of fluid in said microchannel ; and a signal processor for analyzing said sensing signals to determine at least one flow parameter characterizing said flow; characterized in that : at least one pair of electrodes that generate said electric field also generate said sensing signals; wherein said at least one flow parameter is selected from the group consisting of a flow rate, a change in flow rate, a flow direction, a velocity vector field, a change in the velocity field, and a direction of the velocity field vector. a microchannel ; and a sensor system for sensing flow of fluid in said microchannel , the sensor system comprising: a permselective medium positioned to contact the fluid in the microchannel ; a power source ; an arrangement of electrodes , connectable to said power source and arranged to generate an electric field across said permselective medium thereby forming, via the concentration polarization effect, enriched ionic and depleted ionic concentrations in said microchannel near respective opposite ends of said permselective medium , and to generate sensing signals indicative of patterns of said ion concentration that are effected by the flow of fluid in said microchannel ; and a signal processor for analyzing said sensing signals to determine at least one flow parameter characterizing said flow; a permselective medium positioned to contact the fluid in the microchannel ; a power source ; an arrangement of electrodes , connectable to said power source and arranged to generate an electric field across said permselective medium thereby forming, via the concentration polarization effect, enriched ionic and depleted ionic concentrations in said microchannel near respective opposite ends of said permselective medium , and to generate sensing signals indicative of patterns of said ion concentration that are effected by the flow of fluid in said microchannel ; and a signal processor for analyzing said sensing signals to determine at least one flow parameter characterizing said flow; characterized in that : at least one pair of electrodes that generate said electric field also generate said sensing signals; wherein said at least one flow parameter is selected from the group consisting of a flow rate, a change in flow rate, a flow direction, a velocity vector field, a change in the velocity field, and a direction of the velocity field vector. at least one pair of electrodes that generate said electric field also generate said sensing signals; wherein said at least one flow parameter is selected from the group consisting of a flow rate, a change in flow rate, a flow direction, a velocity vector field, a change in the velocity field, and a direction of the velocity field vector. <EOS>