(241d) Nanostructures for Biosensing

Recent technological advances have enabled high-throughput fabrication of plasmonic nanogap structures with critical dimensions approaching 1 nm. Extreme confinement of optical energy in such single-nanometer gaps can lead to a series of new applications in biosensing and spectroscopy. This presentation will outline approaches to design and fabricate nanogap plasmonic sensors with precisely tuned optical resonances in the visible, near-infrared, or mid-infrared regime. Among various options, we use atomic layer deposition (ALD) to create a dense array of ultra-narrow slits and rings in metals, which is made possible by the Angstrom-scale thickness resolution of ALD. Our scheme – atomic layer lithography - has enabled rapid wafer-scale production of various nanostructures that are nontrivial to produce using any other methods. For example, now it is a routine task to produce a dense wafer-scale array of 1-nm-wide metal slit that is as long as ~1 cm in length. Metasurfaces made with such nanoslits and rings that are resonant in the visible, infrared, and even terahertz regime have been produced over a 4-inch wafer.

Since the nanogap size in our scheme can be precisely controlled with ALD to match the size of target biomolecules, the resulting nanogap structures can be used for trapping and detection of single molecules and nanoparticles. High-throughput production of these nanostructures allows researchers to perform such challenging experiments in a more reproducible manner. We will present experimental results on how to combine optical and electronic trapping techniques with these nanoplasmonic sensors to accomplish single-molecule trapping and detection.