MRI: Development of an Optical Super-resolution Instrument for Measuring Concentration Profiles and Diffusion Dynamics in Thin Films

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This is a project to develop an instrument that will enable new discoveries about material interfaces. A vast range of scientifically and technologically important processes occur at interfaces between solids and liquids. For example, the adhesion of one material to another, the cleaning and disinfection of hospital surfaces, the charging of batteries, and the recovery of oil are all processes that occur at interfaces between solids and liquids. The project will develop a new type of microscopy that will reveal the microscopic details of these interfaces in greater detail and at much greater speed than previously obtainable. The microscope will make it possible to observe changes in structure as quickly as one-millionth of a second. Such high speeds are required to help researchers understand and engineers improve industrial and medical processes that increase the nation’s productivity and well-being. An integral part of the project will be to train future generations of scientists and engineers. The project will provide training in the following areas (1) female high school students, (2) undergraduate students, and (3) students studying to complete Ph.D. programs. Such students go on to provide the workforce that is trained for work in high-tech industries as well as the future generation of researchers. The instrument developed in this project will implement a RESOLFT (Reversible Saturable Optical Fluorescence Transitions) optical super-resolution microscopy technique adapted to study the distribution and dynamics of fluorescently labelled species at solid–liquid interfaces. Specifically, the instrument will be optimized for the highest possible axial resolution through the interference of two counterpropagating beams focused at the interface, and make use of the Ground State Depletion (GSD) modality. It will enable axial resolution as high as 10 nm while studying time-evolution of processes down to 0.25 microseconds, all while maintaining lateral resolution of a standard confocal microscope. The combination of high-resolution profiling and fast time resolution allows the instrument to address a range of unmet characterization needs in materials science, surface science, electrochemistry, polymer science, and adjacent fields. Examples of systems that could be studied with the instrument include spatial distribution of polymers and ions, which is crucial for antimicrobial performance, interactions between biomolecules and interfaces, such as polymers with cell membranes, the dynamics of nanoparticle self-assembly on surfaces, which must be understood to harness self-assembly for practical applications, and dynamics of ion transport near electrodes, which is of great interest in batteries and other electrochemical systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.