A liquid sensor for a diaper, and method of manufacturing the same are provided. The liquid sensor includes a plurality of electrochemical cells in series connection. Each of the plurality of electrochemical cells includes an anode, a cathode and a liquid-porous layer including an electrolyte solution. The liquid-porous layer electrically connects the anode to the cathode such that each cell has a respective predetermined potential difference across the cell. Two or more of the plurality of electrochemical cells are operable to be electrically connected by a liquid to form a single electrochemical cell having a potential difference lower than the sum of the predetermined potential differences of the two or more electrochemical cells.
