## 4 Results and Discussion  
The properties and related parameters of the MXene-based IDE capacitive humidity sensor are shown in Figure 8.  
Figure 7: The diffusion coefficient of water molecules in the MXene-based sensitive layer at different temperatures (black line) and the response time of the sensitive layer with a thickness of 1 μm (red line). The electrical output of the sensor depends on the humidity of the environment in which the sensor is located. In different humidity environments, the dielectric coefficient and capacitance of the sensitive material are different because the sensitive material is limited by different concentrations of water molecules. In addition, the capacitance of the sensor is affected by the actual current. As the current increases, so does the sensor's capacitance, but the electric field is not necessarily fully contained in the sensitive layer. Only the current in the sensitive layer affects the capacitance of the sensor. For the effect of structure on static properties, the thickness affects the current fraction passing through the sensitive layer. The greater the thickness, the greater the current passing through the sensitive layer and the greater the capacitance. However, when the thickness increases to a certain extent, the current has all passed through the sensitive layer. At this phase, increasing the thickness does not increase the capacitance. This shows that the traditional method of improving the sensitivity by increasing the film thickness has limitations. When the sensitivity cannot be improved by increasing the film thickness, other methods, such as improving the dielectric coefficient of the material through material modification, should be used to further improve the sensitivity. Under the same relative humidity, the concentration of water molecules increases with temperature, due to the variance of the static properties of the material. The increase in water molecules leads to an increase in the dielectric coefficient of humidity-sensitive materials, which increases the capacitance of the humidity-sensor output. The results show that temperature can be used to adjust the characteristics of sensor materials, and the dielectric coefficient of humidity-sensitive materials can be adjusted by adding heating elements and other methods. From this, it can also be seen that the dielectric coefficient of humidity-sensitive materials is related to the materials' properties, and similar effects can be achieved by adjusting the dielectric coefficient through other methods. For the effect of structure on dynamic properties, when the thickness is small, increasing the thickness will not lead to a significant increase in the response time. The reason for that is the thickness of the sensitive layer is very small, and the water molecules are still mainly absorbed on the surface of the sensitive layer. In such conditions, it is the characteristics of the material itself that affect the electrical properties, but when the thickness increase continuously, the response time increases with the thickness because water molecules pass through the surface and combine with the hydrophilic groups inside the film. The time required for complete binding is positively related to the thickness. At this  
Figure 8: Schematic diagram of properties and related parameters of the MXene-based IDE capacitive humidity sensor. phase, the main effect on the electrical properties is the concentration of water molecules combined with the sensitive layer. For the effect of material on dynamic properties, when the temperature increases, the water molecules move more violently, leading to an increase in the diffusion coefficient. The time for the water molecules to completely combine with the hydrophilic groups in the sensitive layer decreases, so the response time decreases. To sum up, as the thickness of the sensitive layer increases, the sensitivity of the sensor can be increased until the current completely passes through the sensitive layer. However, this also causes the response time to increase.