Issue 14, 2019

A nanochannel through a plasmonic antenna gap: an integrated device for single particle counting

Abstract

Plasmonic nanoantennas are ideal for single molecule detection since they nano-focus the light beyond diffraction and enhance the optical fields by several orders of magnitude. But delivering the molecules into these nanometric hot-spots is a real challenge. Here, we present a dynamic sensor, with label-free real-time detection capabilities, which can detect and count molecules and particles one by one in their native environment independently of their concentration. To this end, we have integrated a 35 nm gap plasmonic bowtie antenna with a 30 nm × 30 nm nanochannel. The channel runs through the antenna gap, and delivers the analyte directly into the hot spot. We show how the antenna probes into zeptoliter volumes inside the nanochannel by observing the dark field resonance shift during the filling process of a non-fluorescent liquid. Moreover, we detect and count single quantum dots, one by one, at ultra-high concentrations of up to 25 mg mL−1. The nano-focusing of light, reduces the observation volume in five orders of magnitude compared to the diffraction limited spot, beating the diffraction limit. These results prove the unique sensitivity of the device and in the future can be extended to detection of a variety of molecules for biomedical applications.

Graphical abstract: A nanochannel through a plasmonic antenna gap: an integrated device for single particle counting

Supplementary files

Article information

Article type
Paper
Submitted
21 feb 2019
Accepted
07 jun 2019
First published
11 jun 2019
This article is Open Access
Creative Commons BY-NC license

Lab Chip, 2019,19, 2394-2403

A nanochannel through a plasmonic antenna gap: an integrated device for single particle counting

I. Fernandez-Cuesta, M. M. West, E. Montinaro, A. Schwartzberg and S. Cabrini, Lab Chip, 2019, 19, 2394 DOI: 10.1039/C9LC00186G

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