Nanopore-Templated Silver Nanoparticle Arrays Photopolymerized in Zero-Mode Waveguides

Abstract

In situ fabrication of nanostructures within a solid-polymer electrolyte confined to subwavelength-diameter nanoapertures is a promising approach for producing nanomaterials for nanophotonic and chemical sensing applications. The solid-polymer electrolyte can be patterned by lithographic photopolymerization of poly(ethylene glycol) diacrylate (PEGDA)-based silver cation (Ag + )-containing polyelectrolyte. Here, we present a new method for fabricating nanopore-templated Ag nanoparticle (AgNP) arrays by in situ photopolymerization using a zero-mode waveguide (ZMW) array to simultaneously template embedded AgNPs and control the spatial distribution of the optical field used for photopolymerization. The approach starts with an array of nanopores fabricated by sequential layer-by-layer deposition and focused ion beam milling. These structures have an optically transparent bottom, allowing access of the optical radiation to the attoliter-volume ZMW region to photopolymerize a PEGDA monomer solution containing AgNPs and Ag + . The electric field intensity distribution is calculated for various ZMW optical cladding layer thicknesses using finite-element simulations, closely following the light-blocking efficiency of the optical cladding layer. The fidelity of the polyelectrolyte nanopillar pattern was optimized with respect to experimental conditions, including the presence or absence of Ag + and AgNPs and the concentrations of PEGDA and Ag + . The self-templated approach for photopatterning high-resolution photolabile polyelectrolyte nanostructures directly within a ZMW array could lead to a new class of metamaterials formed by embedding metal nanoparticles within a dielectric in a well-defined spatial array.

Membrane-Suspended Nanopores in Microchip Arrays for Stochastic Transport Recording and Sensing

“…A promising direction for optical single-molecule detection with nanopores are zero-mode waveguides (ZMWs). ZMWs are small holes in metal films with sub-wavelength apertures for nanophotonic and sensing applications (Assad et al, 2017;Larkin et al, 2017;Han et al, 2019;Spitzberg et al, 2019) as commercialized by Pacific Biosciences for DNA sequencing (Levene et al, 2003;Foquet et al, 2008;Korlach et al, 2008;Lundquist et al, 2008;Eid et al, 2009;Metzker, 2010;Uemura et al, 2010). As the wavelength of light is smaller than the nanoaperture itself, light cannot penetrate in the confined chamber, which results in an exponential decay of the optical field creating a zeptoliter volume (Levene et al, 2003;Foquet et al, 2008).…”

Design of a Current Sensing System with TIA Gain of 160 dBΩ and Input-Referred Noise of 1.8 pArms for Biosensor

“…The nanopore can control the current with the gate voltage, or be turned off so that the current does not flow [ 15 , 16 , 17 ]. In addition, since nanopores can be fabricated as an array [ 18 , 19 ], each nanopore can react to a different virus; and by controlling each nanopore with a gate voltage and reading each current, multiple viruses can be detected with a single biosensor.…”

Single-Entity Detection With TEM-Fabricated Nanopores

“…Diverse techniques have been developed for nanopore fabrication on thin films, including chemical etching, dielectric breakdown methods, e-beam sculpting, focus ion beam, and electron beam drilling (Han et al, 2019). Among these methods, transmission electron microscopy (TEM) nanopore drilling is the most popular for thin membranes.…”