SBIR-STTR Award

This Small Business Innovation Research (SBIR) Phase I project will develop a realtime surface energy sensor that can be integrated into existing surface treatment systems to provide process control feedback. This sensor is based on a rapid microwetting measurement that is exceptionally responsive to surface free energy. Wetting measurements are a standard technique for determining surface free energies, but are slow and unwieldy to perform. The proposed approach involves ballistic deposition of a minute quantity of a probe fluid onto the surface. The vibration that accompanies deposition greatly facilitates attainment of equilibrium wetting of the surface. An image of the droplet is analyzed to determine the angle formed by the droplet tangent and the surface from drop volume and average diameter, which is a known function of the surface free energy. The equipment to accomplish this task can be readily integrated into existing robotically deployed surface treatment devices.

The broader impact/commercial potential of this project will be to improve quality and yield of manufactured products through rapid, automated, and quantitative control of surface treatment properties. It will allow quantitative surface energy measurements, used for decades in laboratory settings, to transition into automated manufacturing control environments. Scientific and technological understanding will be enhanced by a deeper understanding of the effect of various surface treatment processes on extent and uniformity of surface energy and of the relationship of these properties to adhesion. This project will allow for more efficient, higher yield manufacturing processes that will increase the competitiveness of our domestic manufacturing. The initial market for this technology will include automotive OEM?s and their Tier suppliers, medical device manufacturers and manufacturers of consumer and industrial electronics, and food packaging.

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.