Temperature-Controllable Electrodes with a One-Parameter Calibration

Electrically heated electrodes have been applied for various chemical and biological sensors. However, previous electrically heated electrodes, including microwires and microdiscs, are usually small and often suffer from the requirement of frequent calibrations of the electrode surface temperature (T-s) at different environment temperatures. Here, we fabricate a temperature-controllable disk electrode (TCDE) with a conventional size (3-5 mm in diameter). A one-parameter temperature calibration is proposed using a temperature transfer coefficient alpha and a structural model (T-s = T-e + alpha (T-h - T-e)) to estimate T-s (T-h and T-e are the temperature of the heating element and environment, respectively). The value of alpha is unique for a TCDE and mainly dependent on the structure and materials of the electrodes and the solution in nature. Once alpha is experimentally determined, T-s can be calibrated and found to be applicable to wide fluctuations in room temperature (15.0-33.0 degrees C) with errors below 1.5% for three types of disk electrodes (gold, glassy carbon, and platinum). The required T-s can be obtained by just setting T-h without thermal characterization between the heating power and T-s. A simple relationship for exploring the dependence of alpha on the height (H) and radius (R) of the electrode materials and other constants (a, b, c, and R-0), alpha = 1 - c - aH - b (R - R-0)(2), is revealed by numerical simulations (COMSOL). The impact of the radii of both the insulating materials of the electrode and the electrochemical cells on T-s is also considered. The effect of the solution thermal conductivity on alpha is studied. TCDEs are expected to be used as a sensor platform with enhanced performance.