Ultrafast photomechanical transduction through thermophoretic implosion

Abstract

Since the historical experiments of Crookes, the direct manipulation of matter by light has been both a challenge and a source of scientific debate. Here we show that laser illumination allows to displace a vial of nanoparticle solution over centimetre-scale distances. Cantilever-based force measurements show that the movement is due to millisecond-long force spikes, which are synchronised with a sound emission. We observe that the nanoparticles undergo negative thermophoresis, and ultrafast imaging reveals that the force spikes are followed by the explosive growth of a bubble in the solution. We propose a mechanism accounting for the propulsion based on a thermophoretic instability of the nanoparticle cloud, analogous to the Jeans’s instability that occurs in gravitational systems. Our experiments demonstrate a new type of laser propulsion and a remarkably violent actuation of soft matter, reminiscent of the strategy used by certain plants to propel their spores.

Opto-Thermophoretic Manipulation

“…It has been demonstrated that the laser irradiation of the lead sulfide (PbS) nanoparticle solution inside a closed vial can displace the vial over millimeter-scale distances. 55 The movement is caused by the millisecond-long force spikes, which arise from the coordinated effect among negative thermophoresis, the Jeans' instability, and bubble cavitation. As shown in Figure 3g, when the 980 nm laser is launched from one side, the vial jumped away from the light source over a few millimeters within 1 s.…”

“…(g) Snapshots of macroscopic motion of the vial during one laser-induced jump. Adapted with permission under a Creative Commons Attribution 4.0 International (CC BY) license from ref . Copyright 2020 Springer Nature.…”

The prospective of Artificial Intelligence in COVID-19 Pandemic

“…Nevertheless, CT alone may have limited negative predictive value for ruling out SARS-CoV-2 infection, as some patients may have normal radiological findings at the early stages of the disease but, might be corona infected. The AI techniques integrated with the conventional diagnosis can provide robust solution during the screening process [ 16 , 17 ]. The thermal face scanners, analysis of medical imaging reports by AI-enabled tools and COVID-19 voice detection platforms are the different ways in which AI is revolutionising COVID-19 screening and diagnosis.…”

Strong and fast rising pressure waves emitted by plasmonic vapor nanobubbles

“…It has long been recognized that nanobubble generation around optically heated nano-and micro-objects [24] induces the emission of strong pressure waves [9][10][11]. One macroscopic consequence is a giant photomechanical effect [25], seen in interacting assemblies of nanoparticles with negative thermophoresis. At the microscopic scale, the acoustic emission concomitant to nanobubble generation opens the way to destruction of cancer cells at a subcellular level [26,27].…”