This issue is crucial, and the core of ensuring the accuracy of the optical contact angle measuring instrument test results is to control the consistency of the sample, instrument, environment, and operation.
1、 Sample Preparation Specification
Ensure that the surface of the sample is clean and free of contaminants. Before testing, clean it thoroughly with a suitable solvent and dry it thoroughly to avoid oil stains and dust affecting the spread of droplets.
The surface of the sample should be flat and uniform, without scratches, pores, or roughness differences. If necessary, pre-treatment such as polishing and cutting should be carried out.
The same batch of samples should maintain the same thickness and material condition to avoid fluctuations in results caused by differences in the samples themselves.
2、 Instrument calibration and maintenance
Regularly calibrate the optical system, check lens cleanliness and imaging clarity, and ensure accurate capture of droplet contours.
Calibrate the droplet system, confirm the accuracy of the syringe's liquid output, and avoid inconsistent droplet volumes (usually recommended droplet volumes of 1-5 μ L).
Regularly maintain the mechanical structure of the instrument to ensure the horizontal and accurate movement of the sample stage, and avoid sample or droplet displacement during the testing process.
3、 Test environment control
Maintain a stable temperature in the testing environment (recommended 23 ± 2 ℃), as temperature changes can affect the surface tension and contact angle values of the liquid.
Control the humidity of the environment appropriately to avoid high humidity causing the sample to absorb moisture or droplets to evaporate rapidly.
There is no airflow interference in the testing area to prevent liquid droplets from being blown and deformed, which may affect contour analysis.
4、 Standardization of operating procedures
After the droplet is deposited, let it stand for 1-3 seconds before measuring. Wait for the droplet to reach a stable state with the sample surface to avoid instantaneous contact angle interference.
Repeat the same test point at least 3-5 times and take the average as the final result to reduce random errors.
Adopting a unified contact angle analysis method (such as circle fitting, ellipse fitting, Young Laplace equation fitting) to avoid calculation bias caused by different methods.
5、 Auxiliary verification measures
Use standard reference materials (such as silicon wafers or glass with known contact angles) for regular verification to determine if the instrument is in normal condition.
Record detailed parameters of each test (sample information, environmental conditions, instrument settings) for easy result traceability and anomaly investigation.