A sensing unit model with an anode-cathode-cathode-anode（ACCA） four-electrode array placed in mixed solution environment of KI and I2 is established based on electrochemical principle that a changing ion concentration gradient of the electrolyte resulting from the relative motion of electrolyte and electrodes can change electrode currents. Through theoretical analysis

additional current can be produced by the sensing cell based on relative motion of partial electrolyte（liquid inertial mass） and electrodes. This additional current is proportional to acceleration（0 < a x< 0. 149 m / s2） indicated by further modeling and simulation and thus can be output after amplifying to characterize the acceleration. The process of MEMS can be used to fabricate and package the sensing unit into acceleration sensor.