| 摘要(英) |
In recent years, droplet-based microfluidic systems have been popular topics. There are lots of application of droplet manipulation in several industries, such as chemical and biology. Different methods of actuating droplets are available now, for example, electrostatic, surface structural gradient, and thermocapillary.
Thermocapillary method is easier to control and cost lower energy. Traditional thermocapillary method is usually based on droplet lay on solid substrate. But there may be some disadvantages like droplet pinning, droplet evaporation, substrate contamination and irreversibility. To overcome the shortcomings of traditional liquid-solid thermalcapillary method, we use silicone oil as platform and DI water droplets to demonstrate a liquid-liquid manipulation.
In this research, we partially heat up silicone oil platform in a copper based container by heater at the bottom and partially cool down by a cooler at the other side to provide temperature gradients. When silicone oil around heater is heated, the surface tension will decrease and then pulled to the colder side. So the surface profile of silicon oil platform is like a ramp. Droplets will move from the cold side to hot side. We apply different temperature gradients, silicone oil surface height and different droplet sizes to determine their relationship.
When the silicone oil surface height achieve a specific value, the effect of heat convection of the silicone oil will overcome the gravity force caused by thermocapillary effect and then drag the droplets to migrate from hot side to cold side. We get the largest droplet velocity 8.07 mm/s at 2 mm surface height with 0.326℃/mm of temperature gradient and droplet size of 6 μL.
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| 參考文獻 |
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