Issue 5, 2019

Nanoscale uniformity in the active tuning of a plasmonic array by polymer gel volume change


Active plasmonic tuning is an attractive but challenging research subject, leading to various promising applications. As one of the approaches, nanostructures are placed in or on soft matter, such as elastomers and gels, and their gap distances are tuned by the mechanical extension or volume change of the supporting matrices. As hydrogels possess various types of stimuli-responsiveness with large volume change and biocompatibility, they are good candidates as supporting materials for active nanostructure tuning. However, it remains unclear how accurately we can control their nanogap distance changes using polymer gels with a low deviation due to major difficulties in the precise observation of nanostructures on the gels. Here, we prepared gold arrays with sub-100 nm dots on silicon substrates by electron beam lithography and transferred them onto the hydrogel surface. Then, their nanopattern was actively tuned by the changes in gel size in water and their structural changes were confirmed by optical microscopy, microspectroscopy, and atomic force microscopy (AFM). Further, we successfully prepared ionic liquid (IL) gels with various degrees of swelling via solvent exchange. Scanning electron microscopy (SEM) observation of the IL gels provided clear pictures at nanoscale resolution. Finally, we calculated the plasmonic spectra using a finite difference time domain (FDTD) simulation based on the SEM images and compared them with the measured spectra. The results in this study totally support the notion that active changes in plasmonic nanodot patterns via volume changes in the hydrogel are quite homogenous on a several nanometer scale, making them ideal for precise active surface plasmon tuning.

Graphical abstract: Nanoscale uniformity in the active tuning of a plasmonic array by polymer gel volume change

Supplementary files

Article information

Article type
17 Dec 2018
22 Feb 2019
First published
04 Mar 2019
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2019,1, 1731-1739

Nanoscale uniformity in the active tuning of a plasmonic array by polymer gel volume change

S. Hamajima, H. Mitomo, T. Tani, Y. Matsuo, K. Niikura, M. Naya and K. Ijiro, Nanoscale Adv., 2019, 1, 1731 DOI: 10.1039/C8NA00404H

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