温度梯度诱导的液滴热毛细迁移特性

Characteristics of Droplet Thermocapillary Migration Induced by Temperature Gradient

以硅片为基底,以不同体积比的乙醇和丙酮混合物为介质,对温度梯度激励下液滴的热毛细迁移特性进行了研究。分析了液滴在迁移过程中的高度、湿接触直径、接触角以及迁移速度的变化特征,并通过改变温度梯度、液滴体积和表面张力等参数探讨了这些因素对液滴迁移速度的影响。结果表明:在一定的温度梯度下,一定体积的液滴会发生由高温区域向低温区域的定向迁移,当温度梯度达到1.23时,乙醇液滴的最大迁移速度达到35 mm/s,且迁移速度随时间呈逐渐减小的趋势。随着温度梯度和液滴体积的增大,液滴的迁移速度逐渐增大,但是当液滴体积超过10μL时,继续增大液滴体积,液滴的迁移速度变化不再明显。此外,随着表面张力增大,液滴的迁移速度减小,表面张力每增大0.1 mN/m,液滴的迁移速度降低约12%。在考虑了液滴迁移过程中体积变化的基础上,采用力学分析方法建立了液滴迁移的理论模型。

Using silicon wafer as the substrate and ethanol and acetone mixture with different volume ratios as the medium,the thermocapillary migration characteristics of the droplets induced by the temperature gradient were studied.The variation characteristics of droplet height,wet contact diameter,contact angle and migration velocity during migration were analyzed,and the effects of these factors on the droplet migration velocity were discussed by changing the temperature gradient,droplet volume and surface tension.The results show that under a certain temperature gradient,a certain volume of droplets can migrate from the high temperature region to the low temperature region in a directional way.When the temperature gradient reaches 1.23,the maximum migration velocity of the ethanol droplets reaches 35 mm/s,and the migration velocity of the droplets gradually decreases with time.The migration velocity of the droplets gra-dually rises with the increases of temperature gradient and droplet volume.However,when the droplet volume is more than 10μL,the migration velocity of the droplets will not change significantly with the increase of droplet volume.Moreover,the droplet migration velocity decreases with the increase of surface tension.The droplet migration velocity decreases by about 12%when the surface tension increases by 0.1 mN/m.On the basis of considering the volume change during the droplet migration,a theoretical model of droplet migration was established by mechanical analysis method.