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Research Areas

Nano-Optical Trapping with Plasmonic and Dielectric Metasurfaces

Plasmonic nanostructures provide unprecedented capability to confine electromagnetic energy to nanoscale volumes to enhance light matter interaction. We leverage the plasmonic hotspots, which provides sub-wavelength trapping potential wells to stably confine nanoscale objects that have been delivered to the hotspots. We explore the realization of novel lab-on-chip devices for versatile application in transport, trapping and sensing of nano-scale objects. We have introduced novel nanotweezer designs including  electrothermoplasmonic tweezers which enable fast and accurate positioning of target nanometric objects.

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References:

  1. Justus C. Ndukaife, Yi Xuan, A. G. Agwu Nnanna, Alexander V. Kildishev, Vladimir M. Shalaev, Steven T. Wereley, Alexandra Boltasseva, “High-Resolution Large-ensemble Nanoparticles Trapping with Multifunctional Thermoplasmonic Nanohole Metasurface” ACS Nano (2018)
  2. Ndukaife, Justus C., Vladimir M. Shalaev, and Alexandra Boltasseva. “Plasmonics—turning loss into gain.” Science 351.6271 (2016): 334-335.
  3. Ndukaife, Justus C., et al. “Long-range and rapid transport of individual nano-objects by a hybrid electrothermoplasmonic nanotweezer.” Nature Nanotechnology 11.1 (2016): 53.
  4. Ndukaife, Justus C., et al. “Photothermal heating enabled by plasmonic nanostructures for electrokinetic manipulation and sorting of particles.” ACS Nano 8.9 (2014): 9035-9043.

Programmable Directed Self-Assembly

Nanophotonic technologies call urgently for scalable, large scale, and low-cost production of subwavelength optical elements. We explore large scale patterning and directed assembly of nanoscale optical components. To accomplish this, we explore the interplay between near-field optical forces and electric-field induced forces such as electrohydrodynamic flow, dipolar, Coulomb interaction, AC electro-osmosis, and heat-induced forces namely thermophoresis for directed self-assembly and patterning of nanoscale and sub-micron optical materials. Numerical simulations are employed to elucidate the mechanisms for nanoparticle assembly.

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Nanophotonic biosensors for point-of-care diagnostics

A key interest is in exploring the life science applications of the devices we are developing. In this area, we design and fabricate novel plasmonic nanostructures and resonant dielectric structures for highly sensitive label-free detection of biological molecules. In particular, we design resonant dielectric nanostructures supporting quasi-bound states in the continuum collective resonance, which results in ultra-sharp resonance spectrum that can be tuned across visible, near IR and mid-IR wavelengths. The mid-IR absorption of biological molecules such as protein is an indication of signature of the protein as well it’s primary and secondary structure that determines protein function.