Surface microstructuring to modify wettability for 3D printing of nano-filled inks

This paper investigates the effect of surface wettability on the cross-sectional profiles of printed nanofluid inks which can have a significant role on conductivity of printed lines that are used in the production of printed electronics. Glass substrates were coated with heptadecafluorodecyltrichlorosilane, nonafluorohexyltrimethoxysilane and methyltrimethoxysilane using a dipping method to enhance the wettability of the nanofluid silver ink. Inkjet printing techniques were also applied to develop micro-structural textures on the surface of the glass substrate and thereby modify the wettability of the substrate. The glass substrate, coated with heptadecafluorodecyltrichlorosilane was micro-structured using a UV curable ink to enhance the wettability for the silver nanoparticle ink. Using inkjet printing techniques to micro-structure the substrate allows modification of the wettability of the substrate whilst simultaneously printing on to the substrate. This enables the potential of increasing the performance of such printed lines, essentially permitting additional particulate material to be deposited thus increasing conductivity. The cross-sectional profile of the printed line was predicted numerically and analytically and compared to experimental data where agreement was observed. In addition, three analytical expressions for printed lines on the substrate were developed by writing the force balance equations in the x, y and z directions on a slice of printed line between z and z + dz.