Constrained Drop Surfactometer (model III) is a next-generation droplet-based surface analysis platform for advanced characterization of surface and interfacial phenomena. Powered by proprietary real-time Axisymmetric Drop Shape Analysis (ADSA) of constrained droplets, CDS-III delivers highly accurate measurements of surface and interfacial properties at gas–liquid and liquid–liquid interfaces. The system is uniquely designed for the study of surface energy, adsorption, molecular self-assembly, and interfacial rheology, with particular strengths in biological and biomedical applications such as pulmonary surfactants, tear film lipid layers (TFLLs), biointerfaces, and complex biological fluids.

Combining multiple analytical instruments into a single integrated platform, CDS-III functions as a static and dynamic surface tensiometer, contact angle meter, Langmuir film balance, and Gibbs surfactometer. A proprietary environmental chamber provides precise control of temperature, humidity, and atmospheric conditions, enabling experiments under controlled and physiologically relevant environments. Equipped with a high-precision servo control system and advanced optical imaging technology, CDS-III offers unique dynamic measurement capabilities for real-time monitoring of interfacial behavior. The system is supported by a powerful ADSA software suite compatible with both online real-time operation and offline image analysis. CDS-III includes the analyzer unit, instrument controller, and dedicated computer workstation, providing a complete solution for cutting-edge surface and interfacial research.