Capillary instability in screen-printed micropatterns

Screen printing (SP) has been extensively studied owing to its widespread industrial applications; however, only a few studies have focused on the substrate effect. Herein, we demonstrate that a screen-printed line can undergo a broadening effect or lateral undulation, which is determined by the substrate and printed dimensions. The degree of spreading was systematically investigated by employing 1D and 2D geometrical parameters. Based on the liquidity of the ink, we developed a simple inviscid theory with imposed perturbation to analyze the instability of screen-printed lines. The dispersion relation was derived to estimate the geometry of the laterally undulated lines and compared with the experimental results. The proposed argument is particularly applicable to a regime in which SP inks have greater liquidity. The screen-printed patterns exhibited unique undulated shapes and were utilized as photomasks for the facile fabrication of raccoon-type microchannels.

Automated summary

Screen printing (SP) has been widely studied for industrial applications, but there have been few studies on the effect of substrate. In this study, it is demonstrated that the screen-printed lines can undergo broadening or lateral undulation, which depends on the substrate and printed dimensions. The spreading degree was systematically investigated using 1D and 2D geometrical parameters. Based on the ink's liquidity, a simple inviscid theory with imposed perturbation was developed to analyze the instability of screen-printed lines. The derived dispersion relation was compared with experimental results to estimate the geometry of the undulated lines, particularly in cases where SP inks have higher liquidity. The screen-printed patterns with unique undulated shapes were used as photomasks for the easy fabrication of raccoon-type microchannels.