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

Journal Article · 11 June 2019 · Lab on a Chip

DOI: https://doi.org/10.1039/c9lc00186g · OSTI ID:1526649

Fernandez-Cuesta, Irene  ^[1]; West, Melanie Maputol ^[2]; Montinaro, Enrica ^[2]; Schwartzberg, Adam ^[2]; Cabrini, Stefano ^[2]

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1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Technical Univ. of Denmark, Lyngby (Denmark); Hamburg Univ. (Germany)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

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.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1526649
• Alternate ID(s): OSTI ID: 1596678
• Journal Information: Lab on a Chip, Vol. 19, Issue 14; ISSN 1473-0197
• Publisher: Royal Society of ChemistryCopyright Statement
• Country of Publication: United States
• Language: English