Disposable thermostated electrode system for temperature dependent electrochemical measurements

We describe the fabrication of a screen printed disposable electrode system with integrated elements to allow for control of the working electrode temperature. The device has fully functional working, counter, and reference electrodes with underlying thermocouple and heating elements to allow feedback control of temperature. In our experiments, we determined that the accuracy of the temperature measurements on the electrode was within 0.5 °C over the temperature range of liquid water using a single universal calibration, and we demonstrated that the control system could maintain a setpoint temperature with a root mean squared error of 0.35 °C based on the indicated temperature. We used these electrodes to determine the temperature dependence of the diffusivity of ferricyanide ([Fe(CN)6]3−) ion using linear sweep voltammetry. The diffusion coefficient determined at 25 °C (0.85 × 10−5 cm2 s−1) was similar to other reported values in the literature, although our observed activation energy for diffusion (32.1 kJ mol−1) was significantly higher. Our observed temperature coefficient of −1.63 mV K−1 for the redox potential of the [Fe(CN)6]3−/[Fe(CN)6]4− couple is reasonably close to other reported values. The system shows promise for use in other disposable electrochemical diagnostic systems in which temperature control plays a key role, especially where perturbations or variations in ambient temperature or electrolyte rheological properties make feedback control necessary.