Integrated System for Multitechnique Contact Angle Measurements Under Pressure and Temperature Control

Accurate and precise contact angle measurements are critical for characterizing surface wettability and fluid–solid interfacial phenomena in scientific and engineering applications. However, most high-pressure, high-temperature (HPHT) contact angle instruments are limited to static measurements, while dynamic techniques such as tilted-plate analysis with controlled rotation remain restricted to ambient-pressure conditions. This work presents an integrated measurement system enabling both static and dynamic contact angle measurements using sessile-drop, captive-bubble, and tilted-plate techniques with continuous rotation under controlled pressure and temperature. The system integrates a titanium measurement cell designed for operation up to 50 MPa with a heating system capable of reaching 300~∘ C. It is coupled with a MATLAB-based image-analysis framework that ensures consistent contour extraction, contact-point detection, and contact angle computation across all techniques, thereby enabling direct comparison between techniques, reducing operator-dependent variability, and improving reproducibility. Algorithmic performance was tested using 1600 synthetic droplet contours spanning contact angles from 5° to 173°. Bland–Altman analysis demonstrated strong agreement between the computed contact angles and the known ground-truth values. Measurement precision and system robustness were assessed using 3-D-printed reference substrates containing embedded droplets with predefined geometries. An uncertainty analysis performed in accordance with the Guide to the Expression of Uncertainty in Measurement (GUM) yielded an expanded uncertainty of U \,\,=\,\,4.00∘ at approximately 95% confidence. Experimental demonstrations using a water–N2 system on a quartz surface at pressures up to 10 MPa and temperatures up to 110~∘ C confirmed stable and repeatable performance across all techniques. The proposed system provides a unified and validated platform for HPHT static and dynamic wettability characterization, achieving measurement precision comparable to commercial instruments and uniquely extending experimental capabilities through continuous-rotation tilted-plate measurements under controlled pressure and temperature conditions.