An electrokinetic actuator for a propulsion system is described. The actuator includes an array of channels, with each channel having an inlet and an outlet. A reservoir is included that contains an ionic solution of particles. A first electrode proximate to (or deposited at) the inlet and a second electrode proximate to (or deposited at) the outlet are connected to a voltage source. The voltage source and electrodes apply a voltage across the length of the channels to generate an electric field parallel to each channel. The electric field causes an electro-osmotic flow of ions from the reservoir to the outlet producing electrokinetic thrust at the outlet. By varying the concentration of the ionic solution and the magnitude of the electric field, the electro-osmotic flow of ions is controlled.