The Behaviors of Direct-Written Nanofibers on Patterned Substrate

The Direct-Write (DW) technology based on Near-Field Electrospinning (NFES) is utilized to study the deposition behaviors of nanofibers on silicon substrate patterned with thin film of silicon dioxide (SiO₂). The deposition behaviors of nanofibers on patterned substrate, such as width of distribution area and deposition morphology of direct-written nanofibers on patterned substrate are investigated in this article to accelerate the industrial application of DW technology based on NFES. Due to the repulsion force of charges on nanofibers and the elastic force of nanofibers stem from surface tension force and viscous force, the width of nanofibers distribution area on is bigger than that on Si surface. There is more spacing among nanofibers that deposited on SiO₂ surface, while nanofibers prefer to aggregate together on Si surface. Nanofibers may aggregate to form cluster like twisted structure periodically on the Si surface and two adjacent nanofiber clusters are connected by one single nanofiber. Under the repulsion force and elastic force of charged nanofibers, denser nanofibers would be collected at the junction of Si and SiO₂ surface or on the middle Si area between SiO₂ teeth in comb structure. The effect of CMS on deposition morphology of nanofibers was also investigated. When CMS ranges from 8 to 20 cm/s, wave-shaped nanofibers would be direct-written on both Si and SiO₂ surface. When CMS is in the range of 20~35 cm/s, straight-line nanofibers would be drawn on Si layer but nanofibers on SiO₂ surface of wave-shape. Straight nanofibers can be direct-written on both Si and SiO₂ surface, when CMS is higher than 35 cm/s. These results show that higher CMS is needed to direct-write straight nanofibers on SiO₂ surface than that needed on Si surface.