Screen printing electrode impedance method detection, why does the impedance value continue to decrease with time?

In the screen-printed electrode impedance method detection, the continuous decrease in impedance value over time may be caused by a variety of factors. For the experimental conditions you mentioned, potassium ferricyanide and potassium ferrocyanide are used
The mixed solution is used as a redox couple, and the impedance measurement is performed with a bare electrode and a solution. The following are some possible reasons:
1. Adsorption on the electrode surface
Phenomenon description: Over time, certain components in the solution (such as potassium ferricyanide, potassium ferrocyanide or their reaction products) may be adsorbed on the electrode surface, changing the surface properties of the electrode.
Impact: This adsorption may form a thin film with good conductivity on the electrode surface, thereby reducing the interface resistance between the electrode and the solution.
2. Oxidation or reduction of electrode surface
Phenomenon description: During the experiment, a slow oxidation or reduction reaction may have occurred on the electrode surface, especially when in contact with the mixed solution of potassium ferricyanide and potassium ferrocyanide.
Impact: These reactions may change the chemical state of the electrode surface, causing changes in surface resistance, thereby affecting the overall impedance value.

3. Chemical reactions in solutions
Phenomenon description: The mixed solution of potassium ferricyanide and potassium ferrocyanide may react chemically under certain conditions to generate new substances.
Impact: These newly generated substances may interact with the electrode surface, changing the interface properties between the electrode and the solution, thus affecting the impedance value.
4. Temperature changes
Phenomenon description: Although you did not mention temperature changes, temperature fluctuations during the experiment may also have an impact on the impedance value.
Impact: Changes in temperature will affect the movement speed of ions in the solution and the reaction rate on the electrode surface, thereby changing the impedance value.
5. Removal of contamination from electrode surface
Phenomenon description: At the beginning of the experiment, there may be some trace amounts of contaminants on the electrode surface. Over time, these contaminants may be gradually removed.
Impact: The removal of contaminants will make the surface of the electrode cleaner and smoother, thereby improving its conductivity and reducing its impedance value.
6. Other factors
Electrode aging: After long-term use, the performance of the electrode may gradually decline, including conductivity and stability. This may also result in a decrease in impedance value.
Solution concentration changes: If the solution concentration changes during the experiment (for example, due to evaporation or reaction consumption), this may also have an impact on the impedance value.
in conclusion

In summary, there may be many reasons why the impedance value continues to decrease over time during the screen-printed electrode impedance method detection. In order to accurately determine the specific cause, it is recommended to conduct further control experiments and detailed analysis, such as controlling temperature, detecting changes in substances in the solution, and testing electrodes.
Surface characterization, etc. This will help to deeply understand the mechanism of impedance value changes and optimize experimental conditions to improve detection accuracy and stability.

Disclaimer: Some of the pictures, texts, videos and opinions in this article come from the Internet and other public platforms. The main purpose is to share information so that more people can get the information they need. The copyright belongs to the original author. If there is any infringement, please inform us and we will delete the relevant content within 24 hours. Thanks!