This letter reports a tunable planar optofluidic switch as illustrated by three laminar flow streams introduced into a focusing chamber. Different width of liquid core can be tuned via the imposed flow rate of these three laminar flow streams. The hydrodynamic tunability of the core-cladding interfaces is the key to realize microscale optical switching via total internal reflection. The optical switching capability is demonstrated having good agreement with optical simulations. The optofluidic optical switch can achieve a switching speed of 1.56 Hz and beyond with the potential for a seamless integration with other lab-on-a-chip devices for optical sensing applications.
This paper presents a planar optofluidic lens for light manipulation utilizing a combination of optofluidic biconvex lens with micromixer. Three light manipulation techniques including tunable optical diverging, collimating and focusing are realized by altering the refractive index of the optofluidic variable-focus lenses formed by solid polydimethylsiloxane (PDMS) walls and tunable liquid lens body. The optical power from the laser input can be increased or decreased with the tuning of the variable-focus lenses' refractive indexes. The optical power adjustment capabilities are demonstrated and characterized. The combinations of benefits of all lens' optical manipulation capabilities, greater mechanical stability, significant increase of optofluidic device's life time and seamless integration with other lab-on-a-chip functionalities provide a promising and versatile optofluidic compartment to integrate with lab-on-a-chip excitation and sensing applications. Optofluidic lens-including system for tunable fluorescence sensing is demonstrated showing 186% increase in detected fluorescence intensity.
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