The Generation And Experimental Study Of Microscale Droplets In Drop-On-Demand Inkjet Printing

Abstract

The thesis mainly contains following 3 parts. In the first part, a PET/PTFE-based piezoelectric drop-on-demand inkjet printhead with an interchangeable nozzle design was proposed and fabricated in this thesis. The ejecting capacity of this novel printhead was compared with commercial printheads, and found to have superior performance and versatility. The interchangeable nozzle design largely alleviates the difficulty in cleaning of clogged nozzles and greatly reduces the occurrence of printhead damage. The new printhead shows excellent repeatability. In the second part, the formation of fine jets during the piezoelectric drop-on-demand inkjet printing was investigated using ultra-high-speed video imaging. The speed of the jet could exceed 90 m/s. The diameters of the thinnest jets were of the order of a few microns. Two types of jet were identified during the printing. The study provides a possible way to improve inkjet printing resolution without reducing nozzle diameter. In the last part, the in-house-developed printhead was used for cell printing. L929 rat fibroblast cells have been successfully delivered through nozzles as small as 36 ?m. Cell survival rates were found to be strongly affected by the higher mean shear rates. For pattern printing, cells dispensed onto collagen gel were found to successfully maintain their viability, adhere to the gel, spread and proliferate, forming a denser pattern.