Injection Characteristics of Liquid Jet from a Needle Free Injection Device in the Tissue Simulant

This study aims to investigate the dynamics characteristics of liquid jet injected from a needle-free injection device by analyzing the the flow visualization from the high-speed video camera and the CFD calculation. This is to investigate the jet flow phenomena (e.g. penetration, dispersion, velocity) in the quiescent air and in the tissue simulant (20% polyacrylamide gel) as the further information to apply in the real tissues. The jet injection parameters, which are jet velocity, piston movement, and jet penetration in the tissue simulant, for the needle-free jet injection, are thoroughly investigated by using the high-speed video camera and CFD simulation. In the experimental visualization, a high-speed video camera was used to capture the jet flow phenomena in the medium which are the quiescent air and the 20% polyacrylamide gel used as tissue simulant. Jet injection into the air, both in an experimental and numerical visualization, it is found that when the liquid volume ejected is decreased, the jet velocity slightly increases, and the average velocity of piston movement during jet injection process is found to be steadily decay over remaining 0.15 – 0. 2 m/s after the high velocity pulse during the first 1-10 ms. The CFD results show good agreement to results from experiments both quantitatively and qualitatively. Injecting into 20% polyacrylamide, the jet can be captured by the high speed video camera. The penetration process which consists of three stages which are the threshold stage, the penetrative stage, and the dispersion stage can be revealed.