We propose spin-current microfluidic actuation of a sealed liquid metal. Spin angular momentum injected from Pt contacts enters the liquid as an Einstein-de Haas torque and is converted through micropolar angular-momentum balance into viscous flow without pressure drive, moving walls, magnetic fields, Lorentz forces, or charge flow through the liquid. The dc velocity obeys universal spin-diffusion scaling, and the finite-frequency spin-mechanical admittance resolves viscous momentum diffusion, spin transport, microrotation relaxation, and interface transparency of the liquid-metal channel.
@article{arxiv.2605.25387,
title = {Microfluidic Actuation by Einstein-de Haas Spin Torque},
author = {Xin Hu and Mamoru Matsuo},
journal= {arXiv preprint arXiv:2605.25387},
year = {2026}
}