State Key Laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
J Colloid Interface Sci. 2012 Jan 1;365(1):254-9. doi: 10.1016/j.jcis.2011.09.007. Epub 2011 Sep 10.
Experiments of sessile water droplet evaporation on both polydimethylsiloxane (PDMS) and Teflon surfaces were conducted. All experiments begin with constant contact area mode (the initial contact angle is greater than 90°), switch to constant contact angle mode and end with mixed mode. Based on the assumptions of spherical droplet and uniform concentration gradient, theoretical analyses for both constant contact area and constant contact angle modes are made and theoretical solutions are derived accordingly, especially a theoretical solution of contact angle is presented first for CCR stage with any value of the initial contact angle. Moreover, comparisons between the theoretical solutions and experimental data of contact angle in CCR stage demonstrate the validity of the theoretical solution and it would help for a better understanding and application of water droplet on solid surfaces, which is quite often encountered in lab-on-a-chip, polymerase chain reaction (PCR) and other micro-fluidics devices.
在聚二甲基硅氧烷（PDMS）和特氟龙表面上进行了固着液滴蒸发的实验。所有实验均从恒接触面积模式（初始接触角大于 90°）开始，切换到恒接触角模式，并以混合模式结束。基于球形液滴和均匀浓度梯度的假设，对恒接触面积和恒接触角两种模式进行了理论分析，并推导出了相应的理论解，特别是针对初始接触角任意值的 CCR 阶段提出了接触角的理论解。此外，CCR 阶段接触角的理论解与实验数据的比较验证了理论解的有效性，这有助于更好地理解和应用固着在固体表面的液滴，这在微流控芯片、聚合酶链式反应（PCR）和其他微流控设备中经常遇到。
