Budhwani Karim I, Pekmezi Gerald M, Selim Mohamed M
CerFlux, Inc., Birmingham, AL 35205, USA.
School of Medicine and School of Engineering, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA.
Micromachines (Basel). 2020 Jul 16;11(7):687. doi: 10.3390/mi11070687.
Walking on water is made possible, at least for tiny insects, by molecular interaction at the interfaces of dissimilar materials. Impact of these interactions-surface tension (SFT) and, more broadly, interfacial tension (IFT)-is particularly evident at micro and nano sizescales. Thus, implications of walking on water can be significant for SFT or IFT (S/IFT)-driven nanofabrication technologies, such as electrohydrodynamic atomization (EHDA), in developing next generation biomimetic microphysiological systems (MPS) and drug delivery systems (DDS). However, current methods for estimating S/IFT, based on sessile drops or new surface formation on a ring or plate, are unsuitable for integration with EHDA assemblies used in electrospinning and electrospraying. Here, we show an method for estimating S/IFT specifically devised for EHDA applications using signal processing algorithms that correlate the frequency and periodicity of liquid dispensed in EHDA microdripping mode with numerical solutions from computational fluid dynamics (CFD). Estimated S/IFT was generally in agreement with published ranges for water-air, 70% ethanol-air, chloroform-air, and chloroform-water. SFT for solutions with surfactants decreased with increasing concentrations of surfactant, but at relatively higher than published values. This was anticipated, considering that established methods measure SFT at boundaries with asymmetrically high concentrations of surfactants which lower SFT.
至少对于微小昆虫来说，在水面上行走是通过不同材料界面处的分子相互作用实现的。这些相互作用的影响——表面张力（SFT），更广泛地说，界面张力（IFT）——在微米和纳米尺度上尤为明显。因此，对于基于SFT或IFT（S/IFT）驱动的纳米制造技术，如电流体动力学雾化（EHDA），在开发下一代仿生微生理系统（MPS）和药物递送系统（DDS）方面，在水面上行走的意义可能重大。然而，目前基于静滴或在环或板上形成新表面来估计S/IFT的方法，不适用于与静电纺丝和电喷雾中使用的EHDA组件集成。在这里，我们展示了一种专门为EHDA应用设计的估计S/IFT的方法，该方法使用信号处理算法，将EHDA微滴模式下 dispensed液体的频率和周期性与计算流体动力学（CFD）的数值解相关联。估计的S/IFT通常与水-空气、70%乙醇-空气、氯仿-空气和氯仿-水的已发表范围一致。含有表面活性剂的溶液的SFT随着表面活性剂浓度的增加而降低，但相对高于已发表的值。考虑到既定方法在具有不对称高浓度表面活性剂（会降低SFT）的边界处测量SFT，这是可以预料的。
