The present study aims to reveal the operational characteristics of the needle-free injector. Effects of operating parameters on the injection performance were experimentally investigated. A visualization experiment was performed to describe the dispersion pattern of water in gel. The results show that the peak stagnation pressure increases continuously with the driving pressure. The injection process comprises two distinct stages, which are characterized by the penetration and the dispersion of the drug, respectively. The nozzle diameter imposes a significant effect on the penetration ability of the needle-free injector. As the nozzle diameter increases, the stagnation pressure decreases nearly linearly and the injection duration is considerably shortened, but the jet power is increased. Among the three nozzle diameters investigated, the nozzle diameter of 0.25 mm satisfies the proposed criterion of the injection power. It is evidenced through the visualization experiment that the maximum penetration depth increases with the nozzle diameter. The width of the projection area of the water bulk is insensitive to the nozzle diameter. For a certain nozzle diameter, the projection area of the diffused water bulk increases linearly with increasing liquid volume.
Keywords: Dispersion pattern; Injection power; Jet penetration; Needle-free injection; Stagnation pressure.
Copyright © 2022. Published by Elsevier Ltd.