Sensitive and fast measurement of surface temperature with a thermogalvanic cell

Thermogalvanic cells may be viewed as electrochemical thermocouples. Here, we demonstrate their potential for sensitive and fast sensing of the surface temperature of a thin Au sheet, in contact with a 0.08 M equimolar ferri-/ferrocyanide solution in 26% KOH. We obtained a sensitivity of about 10 μK, because of the large Peltier coefficient of the electrochemical reaction at the electrode-electrolyte junction. The resolution is limited by the thermal noise of the electrochemical system and could be quantitatively explained by the thermal noise of a Randles equivalent circuit of the cell. Since no thermal contact resistances to bulky temperature sensors are involved, we achieved a response time smaller than 300 μs, which may be potentially lowered to a few microseconds. By using the thermogalvanic cell as a sensor for electrochemical microcalorimetry, we calibrated the system, in full agreement with a simulation of its thermal behavior.