Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida, USA.
CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, Florida, USA.
Sci Rep. 2017 Jul 11;7(1):5144. doi: 10.1038/s41598-017-05175-6.
Electrosprays operate in several modes depending on the flow rate and electric potential. This allows the deposition of droplets containing nanoparticles into discrete nanodot arrays to fabricate various electronic devices. In this study, seven different suspensions with varying properties were investigated. In the dripping mode, the normalized dropsize decreases linearly with electric capillary number, Ca , (ratio of electric to surface tension forces) up to Ca ≈ 1.0. The effect of viscous forces is found to be negligible in the dripping mode since the capillary number is small. For flow rates with low Reynolds number, the mode changes to microdripping mode, and then to a planar oscillating microdripping mode as Ca increases. The normalized dropsize remains nearly constant at 0.07 for Ca > 3.3. The microdripping mode which is important for depositing discrete array of nanodots is found to occur in the range, 2 ≤ Ca ≤ 2.5. The droplet frequency increases steadily from dripping to microdripping mode, but stays roughly constant in the oscillating microdripping mode. This work provides a physical basis by which the flow rate and the voltage can be chosen for any nanosuspension to precisely operate in the microdripping mode at a predetermined dropsize and droplet frequency.
电喷雾在几种模式下运行，具体取决于流速和电势。这允许将含有纳米颗粒的液滴沉积到离散的纳米点阵列中，以制造各种电子设备。在本研究中，研究了具有不同性质的七种不同悬浮液。在滴落模式下，归一化液滴尺寸随电毛细数 Ca（电场力与表面张力之比）线性减小，直至 Ca≈1.0。由于毛细数较小，发现在滴落模式下粘性力的影响可以忽略不计。对于低雷诺数的流速，模式会变为微滴落模式，然后随着 Ca 的增加变为平面振荡微滴落模式。归一化液滴尺寸在 Ca>3.3 时保持在 0.07 左右几乎不变。对于沉积离散纳米点阵列很重要的微滴落模式，发现其发生在 2≤Ca≤2.5 的范围内。液滴频率从滴落模式稳定增加到微滴落模式，但在振荡微滴落模式中大致保持不变。这项工作提供了一个物理基础，可以根据流速和电压选择任何纳米悬浮液，以便在预定的液滴尺寸和液滴频率下精确地在微滴落模式下运行。
