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The no-slip boundary condition is a signature characteristic of laminar flow, and the Tesla turbine leverages this condition to transfer mechanical rotation into fluidic pressure. This means that the Tesla turbine is optimally driven by microfluidic flow, which maximizes the use of the boundary layer flow. To this end, we employed a lithography based high resolution 3D printing to realize an embedded micro Tesla pump smaller than the diameter of a penny, integrated to a microfluidic network. The pump was completely sealed in the PDMS (polydimethylsiloxane) device and coupled magnetically to a 3” portable stir plate for rotation. The pump was operated up to 4k rpm (verified with an optical tachometer and slow motion capturing), netting an output pressure of 125 Pa. The pressure transients over time was deconvolved with the rotor transients from the stir plate to yield a pump response function, with a decay constant around 1 second. This means that the pump was able to respond to transients as short as 1 second, and negligible shearing did not affect the rotor-stir plate coupling to ensure efficient pumping. Finally, the pump was applied to drive blue and red dyes into a microfluidic mixer network, demonstrating stable, on-chip fluidic flows without external pumps. The transient characterization of the µTesla pump can provide important insights to the scaling of Tesla pumps and the power transfer between mechanical rotation and fluidic flow, leading to better understanding of the Tesla turbine efficiencies.
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