A sensor using electrophoresis may include a microfluidic channel and electrodes on opposite sides of the microfluidic channel to generate an electric field across, or normal to, the channel. The electric field may be used to drive charged particles of material, particularly material suspended in fluid in the microfluidic channel, toward or away from the one of the electrodes. The electric field may be modulated to allow material to continue flowing through the microfluidic channel, to remove non-target material, or to measure another target material.