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arXiv · 2606.27735

Optothermal Actuation of Unidirectional Thermo-osmotic Flows

Tetsuro Tsuji·Shota Suzuki·Satoshi Taguchi·Haruya Ishida·Hideaki Teshima
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Abstract

In this paper, we experimentally demonstrate the microscale direction control of thermoosmotic flows using a focused-laser heating. The key is the off-center laser irradiation on an immobilized light-absorbing microparticle, which generates a nonuniform, asymmetric heat source. The resulting thermo-osmotic flows are evaluated using the optically trapped particle tracking velocimetry (ot-PTV), presented in our preceding paper (T. Tsuji, et al., Physical Review Fluids 11, 034901 (2026)). It is shown that the flow characteristics can be modulated by the ionic strength of a sample solution and/or the surface molecular coating of the substrate. In particular, the significance of ionic strength on thermo-osmotic flows are discussed based on the surface potential of the substrate measured by frequency-modulated atomic force microscopy.

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Tetsuro Tsuji, Shota Suzuki, Satoshi Taguchi, Haruya Ishida, Hideaki Teshima. 2026-06-26. Optothermal Actuation of Unidirectional Thermo-osmotic Flows. https://arxiv.org/abs/2606.27735

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