SBIR Phase II: Novel Surface Free Energy Sensor

The broader impact/commercial potential of this project will be to allow for more energy efficient surface treatment, more consistency in surface treatment processes, reduced scrap rates in manufacturing and more reliable bonded and coated structures. This in turn will reduce barriers to adoption of these inherently efficient manufacturing methods. Markets that have expressed keen interest in the proposed sensor technology include automotive OEM?s and their suppliers, major airframers and their suppliers, and manufacturers of general purpose surface treatment equipment. Other major markets include manufacturers of medical devices, consumer and industrial electronics, and food packaging. The theoretical and practical knowledge gained through this work will advance the ability to apply these principles to create robust surface free energy sensors. This understanding is critical for controlling many processes that depend on wetting phenomena, including printing, adhesive bonding, painting, rapid prototyping and additive manufacturing, application of agricultural chemicals, and aircraft deicing. This Small Business Innovation Research (SBIR) Phase 2 project will address the needs engendered by the current environmentally mandated shift from solvent-based adhesives and coatings to water-borne systems, which has made the control of surface treatment extremely critical. Currently, surface treatment processes are performed without feedback control. The quality of surface treatment is determined by expensive destructive testing. The proposed sensor is based on ultra rapid determination of the equilibrium shape of a miniscule drop of a probe liquid on the surface in question, a parameter directly related to the Gibbs free energy of the surface. The research objectives are to develop a fundamental understanding of the relationship between ballistic deposition parameters of small liquid drops, the morphology and energetics of a substrate surface, and the equilibrium drop geometry, and utilize this knowledge to design and construct prototype closed loop control surface processing equipment. This understanding will be developed primarily through high-speed imaging of the interaction of growing droplets with surfaces of various chemical composition and morphology. This knowledge will be incorporated into the design and construction of prototype surface processing equipment that includes closed loop feedback for precise control and verification of surface free energy.