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Compact plasmonic optical biosensors based on nanostructured gradient index lenses integrated in microfluidic cells

Abstract

We report on a compact and cost-effective integrated label-free biosensor configuration which is based on the refractive index sensitivity of the localized surface plasmon resonance (LSPR) of gold nanostructures. Aiming for compactification and miniaturization of the sensor, arrays of nanodiscs were fabricated on the planar surface of a gradient index (GRIN) lens, which acts as substrate as well as an imaging objective for the light scattered by the gold structures. Integration of the lens in a microfluidic flow cell enabled the controlled exchange of liquid media at the sensor surface. The light scattered by the nanostructures was investigated spatially and spectrally resolved making use of the imaging properties of the GRIN lens. Dynamic spectral analysis during refractive index changes was conducted, revealing high sensitivities of up to 372 nm per refractive index unit for the shift of the LSPR. Biosensing capabilities were demonstrated by the detection of binding of an analyte by means of a testosterone-immunoassay.

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Publication details

The article was received on 08 Jun 2017, accepted on 02 Oct 2017 and first published on 04 Oct 2017


Article type: Paper
DOI: 10.1039/C7NR04097K
Citation: Nanoscale, 2017, Accepted Manuscript
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    Compact plasmonic optical biosensors based on nanostructured gradient index lenses integrated in microfluidic cells

    A. Horrer, J. Haas, K. Freudenberger, G. Gauglitz, D. P. Kern and M. Fleischer, Nanoscale, 2017, Accepted Manuscript , DOI: 10.1039/C7NR04097K

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