# High‐Throughput Fabrication of Zero‐Mode Waveguide Nanoaperture Arrays with Sol‐Gel Nanoimprint Lithography for Enhanced Single Molecule Fluorescence Detection

## TL;DR

A new, affordable method for making nanoapertures improves single-molecule fluorescence detection for biosensing.

## Contribution

A scalable, low-cost fabrication method for high-performance zero-mode waveguide arrays using sol-gel nanoimprint lithography and vapor-phase etching.

## Key findings

- ZMW nanoapertures achieved up to 8× fluorescence brightness enhancement.
- Sub-millisecond temporal resolution and broadband spectral operation were demonstrated.
- The method enables parallel fabrication without expensive equipment.

## Abstract

Zero‐mode waveguides (ZMWs) are subwavelength metallic nanoapertures enabling enhanced single‐molecule fluorescence detection at micromolar concentrations in conditions far beyond the diffraction‐limited capabilities of confocal microscopes. However, their widespread use remains limited by the complexity and cost of the nanofabrication techniques, such as focused ion beam and electron‐beam lithography. Here, a scalable, cost‐effective, and high‐throughput method for fabricating high‐performance ZMW arrays is presented, which combining sol‐gel nanoimprint lithography (NIL) with hydrofluoric acid (HF) vapor‐phase etching. This approach enables the parallel fabrication and massive replication of ZMW nanoapertures with attoliter volumes, without requiring expensive equipment. The optical performance of the resulting ZMWs is validated through a series of single‐molecule fluorescence experiments, including burst analysis, fluorescence correlation spectroscopy (FCS), and single‐molecule Förster resonance energy transfer (smFRET). The ZMW nanoapertures demonstrate up to 8× fluorescence brightness enhancement, sub‐millisecond temporal resolution, and broadband spectral operation across the visible range. This method represents a significant advance in making nanophotonic devices more accessible, paving the way for a broader adoption of ZMWs in single‐molecule biosensing and integrated nanophotonic systems.

The researchers developed a scalable and cost‐effective method to fabricate zero‐mode waveguide (ZMW) nanoapertures in metallic films using sol‐gel nanoimprint lithography and vapor‐phase etching. These nanostructures confine light to attoliter volumes, enhancing fluorescence brightness and enabling single‐molecule detection at micromolar concentrations. Their approach makes nanophotonic tools more widely accessible for biophysical research.