Thermo‐plasmonics: using metallic nanostructures as nano‐sources of heat

Abstract

Recent years have seen a growing interest in using metal nanostructures to control temperature on the nanoscale. Under illumination at its plasmonic resonance, a metal nanoparticle features enhanced light absorption, turning it into an ideal nano-source of heat, remotely controllable using light. Such a powerful and flexible photothermal scheme is the basis of thermo-plasmonics. Here, the recent progress of this emerging and fast-growing field is reviewed. First, the physics of heat generation in metal nanoparticles is described, under both continuous and pulsed illumination. The second part is dedicated to numerical and experimental methods that have been developed to further understand and engineer plasmonic-assisted heating processes on the nanoscale. Finally, some of the most recent applications based on the heat generated by gold nanoparticles are surveyed, namely photothermal cancer therapy, nanosurgery, drug delivery, photothermal imaging, protein tracking, photoacoustic imaging, nano-chemistry and optofluidics.

Understanding and controlling plasmon-induced convection

“…Thermo-plasmonic convection arises due to the electromagnetic heating in metallic nanostructures that results from dissipative losses 3 . This in turn establishes a temperature gradient and produces buoyancy-driven natural convection currents.…”

“…P lasmonic systems are drawing much attention due to their broad applications in several fields such as biology 1 , sensing 2 , nanoscale heating 3 , nonlinear optics 4,5 , optofluidics [6][7][8] and optical trapping [9][10][11][12][13][14] . Indeed, light-absorbing nanotextured surfaces such as those utilizing metal pads, dipole antennas and bowtie nanoantennas have recently been shown to be very effective for optical manipulation 9,13,15 .…”

Harvesting the loss: surface plasmon-based hot electron photodetection

“…Although much effort has been devoted to mitigating plasmon nonradiative decay, recent research has uncovered exciting opportunities for harnessing the process [27,34], such as in photothermal heat generation [35,36], photovoltaic devices [27,37], photocatalysis [38][39][40], driving material phase transitions [41,42], photon energy conversion [43], and photodetection [44][45][46][47][48][49][50]. For instance, the decay of hot electrons can lead to the local heating of the plasmonic nanostructures, making them candidates for nanoscale heat sources [35,36] for use in cancer therapy [51] and solar steam generation [52,53]. On the contrary, hot electrons can be captured before thermalization by an adjacent semiconductor, providing a novel photoelectrical energy conversion scheme for photovoltaics or for driving chemical reactions [39,40].…”

Optimizing Nanoparticle Designs for Ideal Absorption of Light

“…1,2 Light−matter interaction around nanoparticles is at the core of a wide range applications including optical antennas, 3 light harvesting, 4 thermoplasmonics, 5 and local surface plasmon resonance sensing. 6 In this context, optimizing the design of nanoparticles to maximize absorption of light is of crucial importance.…”