微液滴/超疏水界面作用力在电压下的响应行为研究

Research on the Response Behaviors of Microdroplet/Superhydrophobic Interface Forces under Voltage

固液界面行为的实时调节在微流体控制,芯片实验室等领域具有极强的应用前景。通过固液界面行为测量装置系统研究了微液滴/超疏水表面的相互作用力和黏附行为在电压作用下的响应行为。结果表明,电压作用下微液滴/超疏水表面的相互作用力由润湿力、最大作用力和分离力构成。润湿力、最大作用力和分离力均随着电压的变化经历三个阶段,即静态区的缓慢增加、过渡区的急剧增加和饱和区的保持不变。三种力的变化与电压作用下固液界面黏附能的变化密切相关。理论分析表明,微液滴/超疏水界面的黏附能与超疏水表面的电学性质和电压的平方呈正比。进一步分析发现,实验获得的固液界面黏附能大于理论值,这与电压作用下微液滴在超疏水表面的润湿状态转变密切相关,并通过电润湿滞后实验验证了固液界面黏附能的变化与微液滴润湿状态的关系。结果表明,微液滴/超疏水界面相互作用力和黏附行为可通过外加电压进行实时有效调节,研究结果有望为超疏水表面微液滴的实时控制提供理论和技术指导,为电控微流体技术的发展提供理论基础。

Adjusting the solid/liquid interfacial behaviors has strong application prospects in the fields of microfluidic and lab-on-a-chip et al.The interaction forces and adhesion behaviors at microdroplet/superhydrophobic interface under voltage are systematically studied using a solid/liquid interface behavior measuring device.Results showed that the interaction forces are composed of a wetting force,a maximum force and a separation force under voltage.The wetting force,the maximum force and the separation force varied with voltage.In the static region,the forces increased slowly.In the transition region,the forces increased sharply,however,the forces remained unchanged in the saturation region.The variation of the forces is depended on the adhesion energy between droplet and solid under voltage.Theoretical analysis indicated that the adhesion energy is proportional to the electrical properties of the superhydrophobic surface and the square of the voltage.Further analysis found that the experimental adhesion energy is greater than the theoretical value,which might relate to the transition of the wetting state of droplets under voltage.An electrowetting hysteresis experiment verified that the variation of adhesion energy was related to the wetting state of droplet under voltage.The results show that the interaction forces and adhesion behaviors of the microdroplet/superhydrophobic interface can be effectively adjusted by voltage.The founding is expected to provide a guidance for controlling liquid/solid interfacial behaviors and to enrich the microfluidics theory.