Ultrafast photomechanical transduction through thermophoretic implosion

• Published in: Nature communications Vol. 11; no. 1; pp. 50 - 7
• Main Authors: Kavokine, Nikita, Zou, Shuangyang, Liu, Ruibin, Niguès, Antoine, Zou, Bingsuo, Bocquet, Lydéric
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 02.01.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 147/3; 639/766/189; 639/766/530; Actuation; Force measurement; Gravity; Humanities and Social Sciences; Laser propulsion; multidisciplinary; Nanoparticles; Physics; Science; Science (multidisciplinary); Spikes; Spores; Thermal imaging; Thermophoresis
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-13912-w

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. Here, the authors observe that laser illumination allows to displace a vial of nanoparticle solution over centimetre-scale distances. In order to explain this, they describe a novel mechanism for laser propulsion of a macroscopic object, based on light-induced thermophoresis.