Actively Tunable Collective Localized Surface Plasmons by Responsive Hydrogel Membrane

• Published in: Advanced optical materials 2019-08, Vol.7 (15), p.n/a
• Main Authors: Gisbert Quilis, Nestor, van Dongen, Marcel, Venugopalan, Priyamvada, Kotlarek, Daria, Petri, Christian, Moreno Cencerrado, Alberto, Stanescu, Sorin, Toca Herrera, Jose Luis, Jonas, Ulrich, Möller, Martin, Mourran, Ahmed, Dostalek, Jakub
• Format: Article
• Language: English
• Subjects: active plasmonics; Arrays; Biomolecules; biosensing; Collapse; Electromagnetic fields; Gold; Hydrogels; Isopropylacrylamide; lattice resonance; Materials science; metallic nanoparticles; Nanoparticles; Near infrared radiation; Optics; Plasmons; Refractivity; responsive hydrogels
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.201900342

Collective (lattice) localized surface plasmons (cLSP) with actively tunable and extremely narrow spectral characteristics are reported. They are supported by periodic arrays of gold nanoparticles attached to a stimuli‐responsive hydrogel membrane, which can on demand swell and collapse to reversibly modulate arrays period and surrounding refractive index. In addition, it features a refractive index‐symmetrical geometry that promotes the generation of cLSPs and leads to strong suppression of radiative losses, narrowing the spectral width of the resonance, and increasing of the electromagnetic field intensity. Narrowing of the cLSP spectral band down to 13 nm and its reversible shifting by up to 151 nm is observed in the near infrared part of the spectrum by varying temperature and by solvent exchange for systems with a poly(N‐isopropylacrylamide)‐based hydrogel membrane that is allowed to reversibly swell and collapse in either one or in three dimensions. The reported structures with embedded periodic gold nanoparticle arrays are particularly attractive for biosensing applications as the open hydrogel structure can be efficiently post‐modified with functional moieties, such as specific ligands, and since biomolecules can rapidly diffuse through swollen polymer networks. Actuating of collective (lattice) localized surface plasmons is reported based on the modulating of periodic arrays of gold nanoparticles embedded on the top of pNIPAAm‐based hydrogel membrane. Tethered or free‐standing architectures with reversible shifts of the resonance position up to 151 nm and width of 13 nm are reported and their potential in sensing applications is addressed.