Abstract: Taken the microstructure of mosquitoes and cicada mouthparts as the prototypes, one groove shape bionic needle is design. The conclusion that the groove shape bionic needle has obvious resistance reduction effect is proved through contact dynamic analysis using the method of orthogonal design of experiment. The highest resistance reduction rate can amount to 40.94%; the influence law between the non smooth geometry parameters and the friction on the needle external wall getting in the injecting process is found out. The greatest impact factor of the friction is the groove depth, the minimum width. The relationship between the groove depth, width, and friction is a parabola. The relationship between groove number and friction is linear. The groove number increases, friction decreases. The influence order of factors and optimal levels are determined. The existence of the needle groove structure can reduce the contact area of the needle outer wall and soft tissue and this gap can produce a film of air, reducing the friction coefficient. On the other hand, the liquid can make the skin easy to escape, increasing lubricating effect. According to GB, the puncture tests of nine groove shape bionic needles are taken and the test result has been consistent with the numerical analysis result.

Key words: Drag reduction, Contact analysis, Display dynamics, Engineering bionics, Needle, Orthogonal test, Painless injector, Drawing, Solid granules medium forming, Strain, Stress, Theoretical models