Analysis of heavy-metal-ions using mercury microelectrodes and a solid-state reference electrode fabricated on a Si wafer

We have fabricated micro working electrodes and a reference electrode using semiconductor processes for electrochemical detection of heavy-metal-ions. The stripping voltammetry using mercury electrodes has been used to detect trace concentration of ions. If the applied potential to the mercury electrode is negative than the standard redox potentials of heavy-metal-ions, then the ions existing in liquid are amalgamated into the mercury electrode. After this preconcentration process for a few minutes, the potential is increased linearly in the apposite direction and the amalgamated metals are stripped out into solution. By measuring the current peaks while sweeping the voltage, we can find heavy-metal-ions and their concentrations dissolved in the liquid.