Buckling nanofiber on patterned substrate from near-field electrospinning

Near-Field Electrospinning (NFES) was utilized to research the buckling behaviors of electrospinning nanofiber on the silicon patterned substrate. Nanofiber would be deposited in spiral shape due to the bulking behaviors of jet. Buckling of jet is more obvious under the stronger electrical field and lower collector motion speed (CMS), which leads nanofiber to be deposited in spiral shape. The electrical field strength above the micro-pattern is stronger than other zone, which would enhance the buckling behaviors of charged jet and accelerate the motion speed of nanofiber. Higher CMS is needed to direct-write straight line nanofiber on the top surface of micro-pattern than that on the other zone: nanofiber would be deposited in straight line on all over the surface of the patterned substrate, when CMS is higher than 0.3 m/s; nanofiber deposited in spiral shape on the top surface of micro-pattern but in straight line on the surface of other zone, when CMS ranging from 0.1 m/s to 0.3 m/s; spiral nanofiber deposited all over the surface of patterned substrate, when CMS is lower than 0.1 m/s. Furthermore, nanofiber deposited on the top surface of micro-pattern is stretched more and have smaller diameter. Due to the edge effect of electrical field and elastic force of nanofibers, more nanofibers would be collected on the edge or corner of micro-pattern on the substrate. There is an interesting phenomena, multi-layer coiled nanofiber would be collected nearby the edge of micro-pattern, when CMS is lower than 0.08 m/s. The work would improve the integration of NFES with other micro/nano-fabrication technology.