Mechanically tunable surface plasmon resonance based on gold nanoparticles and elastic membrane polydimethylsiloxane composite

Abstract

Surface plasmon in nanoscaled materials has recently attracted a great deal of attention due to its possibility in a wide range of application. From a practical standpoint, it is desirable for the devices having a tunability of surface plasmon frequency. To achieve this goal, in this study, a composite consisting of two-dimensional gold nanoparticles array embedded in elastic polydimethylsiloxane (PDMS) membrane has been synthesized. Because the elastic PDMS membrane has a high malleability, with an external stress, it is very easy to regulate the interparticle distance in the gold nanoparticle array. The change in the distance between each nanoparticle will alter the surface plasmon interaction, and hence surface plasmon frequency can be manipulated. It is found that when the interparticle distance increases, the enhanced surface plasma mutual coupling will cause the blueshift of surface plasmon resonance frequency. The observed result satisfies the forecast based on electromagnetic theory.

Metal-polymer nanocomposite with stable plasmonic tuning under cyclic strain conditions

“…Active tuning has been recently demonstrated where the plasmonic properties of a nanocomposite are continuously modified by mechanic deformation of the nanoparticle-matrix system in order to change the interparticle distance and hence select different spectral absorption regions. [11][12][13] Deformable nanocomposites have been reported to show plasmonic shifts up to around 70 nm for uniaxial deformations of about 20%.…”

“…15 The functionalization of elastomeric surfaces with noble metal nanoparticles has been proposed as an alternative to obtain stretchable plasmonic nanocomposites: this approach allows a very precise control of nanoparticle size and reciprocal distance; however, surface-functionalized elastomers are quite fragile and their stability has not yet been characterized. [11][12][13] In view of applications, a fundamental issue is the stability of the nanocomposite optical properties upon cyclic strain conditions; to date, no characterization of this aspect is reported in the literature, although there are clear evidences that nanoparticles in an elastomeric matrix are a dynamic system undergoing rearrangement and reorganization upon stretching. 19 Recently, we showed that neutral metal clusters produced in the gas phase and aerodynamically accelerated by a supersonic expansion can be implanted in a Polydimethylsiloxane (PDMS) substrate to obtain a nanocomposite with superior resilience and interesting optical properties for the fabrication of stretchable and conformable reflective gratings; 20,21 this approach is called Supersonic Cluster Beam Implantation (SCBI).…”

“…4 When an elastomer is stretched in one direction, it is simultaneously compressed in the one perpendicular to that of the applied strain. 11,12 The compression degree depends on elastomer Poisson ratio: PDMS has a Poisson ratio of 0.5, so a 50% uniaxial stretching causes a 25% compression inducing a nanoparticle rearrangement and aggregation. 11 The reduction of absorbance that we observe may be mainly due the reduction of the nanocomposite thickness upon stretching, while the nanoparticle volume fraction does not change.…”

A mechanically tunable plasmonic structure composed of a monolayer array of metal-capped colloidal spheres on an elastomeric substrate

“…Except for mechanical tuning, other tuning mechanisms offer a rather small spectral range of tuning. Mechanically tunable plasmonic structures which have already been demonstrated include metal nanoparticles embedded in a polymer matrix [9], and metal gratings [8,10] and nanovoids [11] supported by elastomers. Metal nanoparticles support only localized surface plasmons, while metal gratings support delocalized surface plasmons, but for a single polarization.…”

A stretch-tunable plasmonic structure with a polarization-dependent response

“…Stretchable plasmonic structures have generated increasing interest for actively tuning optical response in a reproducible and continuous way. Through mechanical deformation of elastomeric substrates, spectral shifts in the resonance of plasmonic structures are reported, such as in nanoparticles matrix [13], gratings [14] and metal nanovoids [15]. However, most of the stretch-tunable plasmonics rely on modifying the gaps or cavities within or between the resonant elements which leads to limited working wavelengths.…”