## 5 Conclusions  
In this paper, the static and dynamic characteristics of the MXene-based IDE capacitive humidity sensor are investigated through theoretical modeling and simulation. Structural and material parameters were found to affect sensitivity and response time. The trends of sensor properties with each parameter are more accurately analyzed.  
1. The greater the thickness, the more current flows through the sensitive layer and the greater the capacitance. However, unlike the traditional perception, when the thickness increases to a certain extent, the growing thickness does not increase the capacitance. This is because all current has passed through the sensitive layer at this point.
2. When the thickness is at a tiny level, increasing the thickness does not lead to a significant increase in the response time due to the diffusion mechanism of water molecules. However, with the increase in thickness, the response time is obviously related to the change.
3. In the same relative humidity conditions, the concentration of water molecules increases with temperature. The increase in water molecules results in a rise in the dielectric coefficient of the humidity-sensitive material so that the capacitance of the humidity sensor output has a positive correlation with temperature.
4. When the temperature increases, the water molecules move more vigorously, resulting in a rise in the diffusion coefficient. The reaction response time is shortened by reducing the time for water molecules to fully bind to the hydrophilic groups in the sensitive layer.  
Subsequent studies on the material-sensitive mechanism of MXene explain these phenomena and demonstrate the accuracy of the model. Through this model, we are able to design and test the structural and material parameters of the sensor. This can help to improve the properties of the sensor.  
When it is necessary to improve the sensor properties, it is often desired to improve the sensitivity and reduce the response time. Through the numerical simulation of the structure and material through this theoretical model, the sensors can be designed in the theoretical stage and the structural adjustment and material modification can be carried out in the follow-up. Moreover, this model is different from the simple theoretical analysis. For example, from this model, it can be seen that the sensitivity does not increase with the increase of the thickness. When the thickness is small, increasing the thickness will not lead to a significant increase in the response time. This paper also accurately analyzes the influences of temperature on sensitivity and response time. These makes the simulation of the sensor properties more accurate. Through this model, the influence of the design on the properties of the sensor can be simulated, so that the properties can be controlled. Inaddition, the changes in the structure and material parameters predicted by this model can also be applied to MXene-based gas sensors and mechanical sensors, etc.  
Conceptualization, Y.W. and C.H.; Data curation, Y.W.; Investigation, Y.W.; Methodology, Y.W. and C.H.; Project administration, C.H.; Resources, C.H.; Software, Y.W.; Supervision, D.Z.; Validation, Y.W., Z.L., F.C. and X.Y.; Visualization, Y.W.; Writing--original draft, Y.W.; Writing--review & editing, Y.W. All authors have read and agreed to the published version of the manuscript.  
This work was funded by the National Key R&D Program of China under grant No. 2021 YFB3201502, the National Natural Science Foundation of China under grant No.61827901 and No.62088101, and the Beijing Institute of Technology Research Fund Program for Young Scholars under grant XSQ-202121009.  
Not applicable.  
The authors declare no conflict of interest.