Research On Mechanical Behavior During Microneedle Puncturing Skin

Pricking in skin insertion process of needle has been a problem in the process of diagnosis and treatment of disease, but the stimulus on nerve endings can be reduced with lower inserting force. Therefore, painless is possible if the insertion force is very small. For this purpose, in this paper we propose a new method regarding force reduction using rectilinear vibration device, and study the force reduction effect in combination with experiment regarding puncturing silicon membrane and numerical simulation regarding puncturing pig’s kin.Experimental results show that the inserting force can be significantly reduced if applying vibration to the needle, reaching a maximum reduction of～80%. It is found that the force reduction is affected by the insertion velocity, vibration range, vibration frequency, and needle surface features. Decreasing the insertion velocity and increasing the vibration range and frequency could enhance that force reduction effect. If microstructure exists on the needle surface, the force reduction effect would be enhanced.After conducting uniaxial tension and compression experiments for pig’s kin and subcutaneous fat layer respectively, we found that the corneum and dermis could be regarded as five-parameter viscoelastic material, the subcutaneous fat layer could be looked on as hyperelastic material. A finite element numerical simulation on microneedle inserting into pig’s kin was carried out using the determined material parameters. The force reduction effect of vibration obtained by the simulation is consistent with experimental result. Puncturing force is also influenced by the friction coefficient between needle and pig’s kin. Both simulation and experiment prove that force reduction induced by vibration is a feasible and effective method. This study has an important reference value for the development of new painless injection technology.