Experimental studies were conducted to test the cell performance of silicon sensors incorporating three-phase zirconia electrolyte, which consists of cubic ZrO2-MgO solid solution, monoclinic ZrO2 and Mg2SiO4. The performance of the cell : Mo + MoO2 parallel-to three-phase zirconia electrolyte parallel-to Si (in liquid metal)Mo, was tested with electromagnetic steel. Upon immersion, the sensor generated stable EMFs within 10 to 15 s, and silicon levels could be determined with an accuracy of +/-0.01% by weight.