Design And Verification Of A Needle-free Injection System For Large Animals

Needle-free injection system, as an alternative approach of drug delivery, has two main advantages compared with the traditional needle injectors:less pain and no cross infection. For intensive feeding livestock, the advantages of needle-free injector such as less stress reaction, safer injection, etc., are more prominent.The current thesis is aiming at designing a novel split-type needle-free injection system for the application of livestock. The system parameters which affect the fluid jet were investigated, and the efficacy and safety of the needle-free injection system were evaluated, in order to make the needle-free injection technology applicable to the vaccination of livestock.A mathematical model of the split-type needle-free injection was established based on the theoretical model of the common needle-free injection system. The system design specifications were determined based on the simulation analysis of the mathematical model for the liquid jet.An apparatus which could adjust the impact distance and the driving spring was designed and built. A liquid jet pressure test system was established after carefully studying the current liquid jet of the needle-free injection system. The relationship between the impact distance and jet pressure was studied.A split-type needle-free injector for intensive feeding animals was designed based on the above researches, and the important mechanism was carried on the feasibility analysis.Finally, the needle-free injection system was tested and evaluated from three different perspectives:(1) The colorant was Injected into the muscle of the neck and buttocks sites of the piglet. after that, the depth and diffusion areas of the colorant in the subcutaneous tissue and musculature was checked after dissecting the piglet.(2) The live mycoplasma hyopneumoniae vaccine was jetted by the needle-free injection system, the activity of the vaccine under the high-pressure jet was showed by using the method of CCU(color change unit).(3) The silica gel was used to take the place of human skin, and the safe distance between the nozzle and the human skin was studied by the experiment. The results provide a reference to the design of the safety device for the needle-free injection system.