An agar-based silver|silver chloride reference electrode for use in micro-electrochemistry

A miniaturised Ag|AgCl reference electrode is described which can be easily set up. Its electrochemical behaviour was proven by micro-polarisation curves, electrochemical impedance spectroscopy and potential transients. A saturated potassium chloride solution was used which was solidified by adding agar. The electrode is as small as 800 µm in diameter and 5 mm in length, with further potential for down-sizing. A modified version includes an agar salt bridge in the same capillary. After an induction period of 6 h the potential becomes stable within 1 mV for more than 6 weeks. The electrode shows a slightly different reference potential, which is discussed in terms of the production process.