Stability Analysis of Printed Liquid Elbows.

In this study, a theoretical model was developed to analyze the stability of liquid elbow patterns and validated by experiments. An exemplar system of ethylene glycol continuously deposited on polyethylene terephthalate (PET) was used to study the effects of printing parameters on bulge formation near the elbow corners. In the elbow region, because of the capillary pressure differences, liquids flowed into the concave elbow corner and formed bulges easily after being printed. However, the bulge formation disappeared when the elbow angle is >90°. A simple model based on surface energy analysis was proposed to explain the bulging phenomenon and can successfully predict bulge sizes at steady state. A stability diagram was also calculated to map out the stable regimes. With the guidance of the stability diagram, stable elbow lines without any bulges can be printed with various angles by controlling the thickness of liquids. In summary, this stabilization strategy in this study is effective to maintain the fidelity of printed liquid patterns and provides useful guidelines for printed electronic applications.