Chemical and morphological surface patterning is very common in micro uidic devices to control the ow. In this project, the dynamics of water droplets moving on a iron-doped lithium niobate (Fe:LiNbO3) crystal which has been exposed to optical patterns produced by lenses will be studied. This optowetting technique will exploit the photovoltaic eect of lithium niobate, that creates surface charges upon illumination and enables the control of droplets without xed electrodes. To reduce the friction, the crystal surfaces will be covered with a micrometric lubricant lm (LIS) made of octadecyltrichlorosilane (OTS) impregnated with silicone oil that acts as hydrophobic dielectric layer. The behaviour of the LIS will be investigated by droplet sliding on glass and Fe:LiNbO3 substrates and compared with results from literature. The interaction between charged regions at the Fe:LiNbO3 surface and water will be proved by analyzing pendant droplets falling on the substrates due to the dielectrophoretic force. In the nal experiments, the motion of drops with dierent volumes on straight lines with dierent inclinations imprinted on samples tilted at dierent angles will be observed by means of video recordings.

Motion control of water droplets by means of optical patterns imprinted on Fe:LiNbO3 crystals

Meggiolaro, Alessio
2020/2021

Abstract

Chemical and morphological surface patterning is very common in micro uidic devices to control the ow. In this project, the dynamics of water droplets moving on a iron-doped lithium niobate (Fe:LiNbO3) crystal which has been exposed to optical patterns produced by lenses will be studied. This optowetting technique will exploit the photovoltaic eect of lithium niobate, that creates surface charges upon illumination and enables the control of droplets without xed electrodes. To reduce the friction, the crystal surfaces will be covered with a micrometric lubricant lm (LIS) made of octadecyltrichlorosilane (OTS) impregnated with silicone oil that acts as hydrophobic dielectric layer. The behaviour of the LIS will be investigated by droplet sliding on glass and Fe:LiNbO3 substrates and compared with results from literature. The interaction between charged regions at the Fe:LiNbO3 surface and water will be proved by analyzing pendant droplets falling on the substrates due to the dielectrophoretic force. In the nal experiments, the motion of drops with dierent volumes on straight lines with dierent inclinations imprinted on samples tilted at dierent angles will be observed by means of video recordings.
2020-03-23
67
Microfluidics, Lithium Niobate, LIS, Optowetting, Electrowetting
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12608/21269