Collaborative Research: Liquid Phase Atomic Layer Deposition of Thin Films on Nanoparticles Using Three-Dimensionally Printed Microfluidics

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Nanoparticles are particles between 1 and 100 nanometer in size that possess unique, size-dependent properties due to their high surface area-to-volume ratios. Functional nanoparticles have the potential to benefit society through applications such as drug delivery, magnetic resonance imaging, renewable energy, optoelectronics, and catalysis. These applications rely on an ability to precisely customize the surface chemistry of nanoparticles using thin-film coatings. Nanoparticle thin-film coatings are typically on the order of a few monolayers in thickness, yet must be uniformly applied to individual nanoparticles. This award supports fundamental research into a new, high-precision thin-film nanoparticle coating strategy that overcomes current manufacturing challenges, including coating non-uniformity, by combining principles of atomic layer deposition, three-dimensional printing, and microfluidics. Improving the uniformity of nanoparticle coatings enables new applications of functional nanoparticles across health, energy, and technology sectors. This research award supports public engagement with nanotechnology through hands-on educational demonstrations of nanoparticle applications, with a focus on promoting inclusion for groups historically underrepresented in manufacturing research such as women and minorities. Current challenges in thin-film coating of nanoparticles include particle aggregation, non-uniform coating, limited thickness control, and undesired sensitivity to particle size and morphology. This research award meets these challenges by combining the monolayer-by-monolayer deposition principle of conventional atomic layer deposition with the hydrodynamic nanoparticle manipulation approach known as deterministic lateral displacement to achieve a new nanomanufacturing technology termed 'Liquid Phase Atomic Layer Deposition'. This approach represents a shift from conventional atomic layer deposition based on deposition at the solid-vapor interface to a new deposition physics based on successive adsorption and deposition reactions at the solid-liquid interface. The research studies center on utilizing specially positioned nanoposts within a microfluidic channel to passively transport suspended nanoparticles into discrete, adjacent flow streams of successive reactant and wash solutions. It is hypothesized that the controlled solid-liquid interface phenomena of Liquid Phase Atomic Layer Deposition yields a high degree of precision and uniformity for nanoparticle thin-film coating. The engineering of parallel three-dimensional microfluidic reactors, constructed by means of two-photon direct laser writing-based additive manufacturing, ensures that this method is also high throughput. The research team investigates the phenomenon of Liquid Phase Atomic Layer Deposition through fundamental experimental studies, computational fluid dynamics simulations, and multiphysics finite element modeling.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.