COLLABORATIVE RESEARCH: DMREF: Designing Plasmonic Nanoparticle Assemblies For Active Nanoscale Temperature Control By Exploiting Near- And Far-Field Coupling

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With the support of the DMREF Program and the Division of Chemistry, Professor David J. Masiello from the University of Washington, Professor Stephan Link from Rice University, and Professor Katherine A. Willets from Temple University are developing methods to theoretically design and experimentally realize a new class of periodic 1D and 2D thermal metamaterials. Thermal energy, or heat, flows naturally from hot to cold, making it difficult to create localized thermal “hot spots” even when heat is applied to a single location. Said differently, the degree of spatial correlation between the heat power supplied and the temperature change that it induces is likely to be small. Touching a hot pan’s lid provides a simple and all too familiar example of this effect. As a material’s size is reduced to 10-100s of nanometers, or about 1,000 times smaller than the width of a human hair, depositing and maintaining thermal energy within a small region of space becomes even more challenging. Yet, the ability to control heat flow and thus temperature at both nanoscale (100 nm) and micron-scale (~1-100 μm) dimensions has important implications for applications ranging from big data to nanomedicine. This research project aims to overcome thermal diffusion and achieve long-range global control of spatially-nonuniform heating, using only light to actively control the thermal profile of the materials. Beyond impacting a wide variety of applications, the project will facilitate the interdisciplinary training of students and postdoctoral researchers through student exchange between the three research groups, organization of two new scientific meetings, and the design of a nanotechnology summer camp for middle school students with focus on photothermal materials.The goal of this project is to overcome thermal diffusion through the theoretical design and experimental realization of a new class of periodic 1D and 2D thermal metamaterials. Plasmonic nanoparticle unit cells that are individually capable of hosting spatially-controllable nanoscale thermal profiles will be integrated into periodic lattices, which introduces the possibility for long-range global control of spatially-nonuniform heating upon optical excitation. To achieve this goal, the research team will (i) expand the design and thermal characterization capabilities for multi-particle unit cells that exploit near-field coupling; (ii) engineer photonic band structure to sculpt long-range thermal profiles in 1D and 2D Bravais lattices using light; and (iii) integrate multiple sub-lattices to realize 1D and 2D non-Bravais lattices to actively control both nanoscale and micron-scale thermal profiles using light. Realization of such thermally-active materials will require the coordinated and iterative efforts of a highly-skilled team capable of integrating new theoretical methods for predicting how light energy is transduced into modified thermal profiles with experimental fabrication and characterization techniques to design and quantify temperature across decades of length scales, spanning from below the diffraction limit to millimeters. This project will leverage the iterative theory-experiment-theory feedback loop to expand the genome of actively-controllable photothermal materials.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.