Description
Optical tweezers enable contactless manipulation of nanoparticles and find applications in biology, physics, and chemistry. Both conventional optical tweezers and their counterparts based on nanostructured metals (plasmonic tweezers) rely on Brownian motion to load the trap, which can be slow. Here, we address this limitation by demonstrating a device that uses the AC electro-osmotic (ACEO) effect to generate a conveyor-belt flow, capturing nanoparticles and transporting them towards the device center. Device consists of a dielectric fluid cell sandwiched between a microhole patterned gold film on a glass substrate and ITO-coated glass coverslip. The microhole pattern defined in the thin gold film produces a predominantly tangential electric field upon applying an AC electric filed through the fluid cell using the microhole patterned gold electrode and the ITO-coated glass coverslip as electrodes, which in turn drives the required ACEO-induced fluid motion. Using this platform, we experimentally demonstrate directional transport of 100 nm polystyrene nanospheres dispersed in water under application of an AC voltage. The approach enables tailorable fluid flows inside microfluidic chips without complex nanofabrication, sophisticated optics, or expensive instrumentation, and the fact that it is based on a gold film permits future integration of plasmonic trapping architectures.
| I am the presenting author | Yes |
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