Design and optimization of a nozzle for a needle-free injection system

Abstract

The purpose of this thesis was to develop an optimized nozzle for the needle-free injection device currently under construction in MIT's Bio-Instrumentation Laboratory. Initial predictions from ANSYS, a finite element modeling program, indicated that the injection performance could be noticeably improved with a new nozzle design. After running several flow simulations, a final nozzle design was selected, and a strategy was developed to manufacture the new nozzle. The new nozzle was placed in the injection device and measurements of the jet velocity were recorded via a high speed camera. A 2mm long nozzle with a contoured profile consisting of a linear segment tangent to an arc segment at the nozzle exit produced an exit velocity of 45.5m/s at the end of the injection stroke. This showed almost a 19 percent increase in velocity compared to the older nozzle which produced 38. lm/s upon termination of the injection cycle. However, the results of the new nozzle vary from injection to injection. Thus there is a need for continued testing in the future, and possibly more refined measuring techniques such as depth of penetration into the gel or developing improvements with the current video setup.