Contactless thin-film rheology unveiled by laser-induced nanoscale interface dynamics

Verma, Gopal; Chesneau, Hugo; Chraïbi, Hamza; Delabre, Ulysse; Wunenburger, Régis; Delville, Jean‐Pierre

doi:10.1039/d0sm00978d

Cited by 9 publications

(1 citation statement)

References 62 publications

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“…[35,39] The fringe pattern was self-calibrating for nanoscale measurements and has been used as a direct measurement of laser-induced deformation of the AW interface. [35,40,41] To measure the spatial profile of the AW interface, keeping the pump beam fixed, we scanned the probe beam across the AW interface by translating the mirror M3 (Figure 1a).…”

Section: Resultsmentioning

confidence: 99%

Tunable Optofluidic Curvature for Micromanipulation

Verma,

Yadav,

Shi

et al. 2023

Laser & Photonics Reviews

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Manipulating micro/nanoparticles on deformed liquid interfaces induced by radiation pressure presents an active, non‐invasive, and contactless method. However, a significant challenge arises due to the relatively small magnitude of the radiation force in normal incidence. Nevertheless, this technique holds immense utility in controlling particle movement at interfaces, with numerous applications in both physical and biological contexts. To overcome this, the peculiar properties of total internal reflection (TIR) in retro‐reflection mode are expoited to create a high amplitude bulge on the water surface, which can migrate radius particles as forcibly as the traditional micro‐post paradigm. The bulge height is measured using an interferometric technique, and the underlying physics are demonstrated using an imitated particle with a capillary charge. By shining two pump lasers, an interface shape is created with increasing complexity, and the relative pump laser intensity is tuned to migrate particles in the desired direction. The method provides a non‐invasive and contactless way to remotely actuate almost all types of micro/nanoparticles at the liquid surface.

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Section: Resultsmentioning

confidence: 99%

Tunable Optofluidic Curvature for Micromanipulation

Verma,

Yadav,

Shi

et al. 2023

Laser & Photonics Reviews

Self Cite

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Nanogap-Induced Phase Control Reveals the Momentum of Light Inside the Dielectric Medium

Verma,

Brevik,

Mehlawat

et al. 2024

ACS Photonics

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The deflection of a submerged mirror due to light pressure was used to compare competing theories of light momentum inside a dielectric medium. In this case, a significant bottleneck is to find a mirror that reflects light with zero phase shift without requiring multiple sets of metamaterial mirrors, as conventional mirrors reflect light with a 180°phase shift, demonstrating (formally, as we shall see) the Minkowski momentum. Introducing a nanometric gap between the mirror and the convex lens can vary the phase angle from 0 to 180°, covering the momentum range between the Abraham and Minkowski values (2ℏω 0 /nc, 2nℏω 0 /c). Our study used interferometry to measure the deflection of a submerged, partially metallic-coated vertical cantilever caused by radiation pressure with nanometric precision. Our results showed that light momentum within a dielectric follows Minkowski's form (2nℏω 0 /c) for conventional mirrors. However, with a nanogap between the convex lens and a vertically suspended fiber, the momentum transferred to a submerged mirror varied from 2ℏω 0 /nc to 2nℏω 0 /c, depending on the mirror's phase angle. This approach takes an intriguing step illustrating the rivaling theory of light momentum in a medium: numerical simulations based upon the formula derived by [Mansuripur, M. Phys. Rev. A 2012, 85, 023807]agree with our experimental results. These basic results imply promising applications in microfluidics and optofluidics.

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A versatile interferometric technique for probing the thermophysical properties of complex fluids

et al. 2022

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Laser-induced thermocapillary deformation of liquid surfaces has emerged as a promising tool to precisely characterize the thermophysical properties of pure fluids. However, challenges arise for nanofluid (NF) and soft bio-fluid systems where the direct interaction of the laser generates an intriguing interplay between heating, momentum, and scattering forces which can even damage soft biofluids. Here, we report a versatile, pump-probe-based, rapid, and non-contact interferometric technique that resolves interface dynamics of complex fluids with the precision of ~1 nm in thick-film and 150 pm in thin-film regimes below the thermal limit without the use of lock-in or modulated beams. We characterize the thermophysical properties of complex NF in three exclusively different types of configurations. First, when the NF is heated from the bottom through an opaque substrate, we demonstrate that our methodology permits the measurement of thermophysical properties (viscosity, surface tension, and diffusivity) of complex NF and biofluids. Second, in a top illumination configuration, we show a precise characterization of NF by quantitively isolating the competing forces, taking advantage of the different time scales of these forces. Third, we show the measurement of NF confined in a metal cavity, in which the transient thermoelastic deformation of the metal surface provides the properties of the NF as well as thermo-mechanical properties of the metal. Our results reveal how the dissipative nature of the heatwave allows us to investigate thick-film dynamics in the thin-film regime, thereby suggesting a general approach for precision measurements of complex NFs, biofluids, and optofluidic devices.

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Contactless thin-film rheology unveiled by laser-induced nanoscale interface dynamics

Abstract: One of the classical limitations for the investigation of the local rheology of small scale soft objects and/or confined fluids is related to the difficulty to control mechanical contact and...

Cited by 9 publications

References 62 publications

Tunable Optofluidic Curvature for Micromanipulation

Tunable Optofluidic Curvature for Micromanipulation

Nanogap-Induced Phase Control Reveals the Momentum of Light Inside the Dielectric Medium

A versatile interferometric technique for probing the thermophysical properties of complex fluids

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