Ultrasensitive Surface Acoustic Wave Detection of Collective Plasmonic Heating by Close-Packed Colloidal Gold Nanoparticles Arrays

Abstract

A novel electrical detection method based on surface acoustic wave (SAW) is introduced to investigate the heat generation from a two-dimensional (2D) or three-dimensional (3D) close-packed gold nanoparticle (AuNP) array exhibiting tunable collective surface plasmon resonance (CSPR). We have found that the SAW sensor can detect the CSPR-induced photothermal heating effect. The conversion of absorbed light around the CSPR frequency into heat and subsequent transfer from the AuNP array to the lithium niobate (LiNbO 3 ) substrate allows a dual delay-line SAW system to dynamically measure the resonant frequency change of the SAW oscillator coated with a 2D or 3D AuNP array. The experimental findings indicate that SAW detection provides an ultrasensitive (detection limit of temperature change <1 × 10 –3 °C) electrical readout scheme for measuring the collective plasmonic heating of close-packed AuNP arrays with a linear dynamic range of incident light intensity and a designable CSPR spectral response.