Design and Development of an Automated Contact Angle Tester (ACAT) for Surface Wettability Measurement

The Automated Contact Angle Tester (ACAT) is a fully integrated robotic work cell developed to automate the measurement of surface wettability on 3D-printed materials. Designed for precision, repeatability, and safety, ACAT addresses the limitations of manual contact angle testing by combining programmable robotics, precise liquid dispensing, and a modular software-hardware architecture. The system is composed of three core subsystems: (1) an electrical system including power, control, and safety circuits compliant with industrial standards such as NEC 70, NFPA 79, and UL 508A; (2) a software control system based on a Raspberry Pi and Python, featuring fault detection, GPIO logic, and operator interfaces; and (3) a mechanical system that includes a 3-axis Cartesian robot, pneumatic actuation, and a precision liquid dispenser enclosed within a safety-certified frame. The ACAT enables high-throughput, automated surface characterization and provides a robust platform for future integration into smart manufacturing and materials discovery workflows. This paper details the design methodology, implementation strategies, and system integration required to develop the ACAT platform.