Design And Simulation Of A Novel Compliant Mechanism For Microneedle Array Driving

Microelectromechanical systems(MEMS)are emerging disciplines developed by the combination of microelectronics and mechanical engineering.With the rapid development of MEMS technology,its application has penetrated into more and more fields,and the microneedle-based transdermal drug delivery system is one of the more active application fields.This new mode of administration can be applied to the administration of macromolecular protein drugs,potentially enabling minimally invasive,painless and timed,precise and continuous administration.However,in the research and development of transdermal delivery technology based on microneedles,how to effectively drive microneedles or microneedle arrays to penetrate the skin is a key issue for the commercialization of microneedle arrays.At present,the transdermal drug delivery technology based on microneedles mainly focuses on how to research and manufacture the effective structure of microneedles themselves,so as to better penetrate the skin without breaking,and better achieve drug delivery.Previous studies have rarely demonstrated microneedles with drive devices,let alone to demonstrate a monolithic chip with both microneedles and drive structures.Compliant mechanism based on MEMS has many advantages,such as in-plane manufacturing,easy integration,simple structure,no friction and wear,no need of lubrication and so on.Therefore,it is a good choice as the driving device of micro-needle in MEMS.Firstly,the background and significance of this research are described,the research status at home and abroad is introduced,and the future development trend of this field is discussed.Based on the model of the straight flexible cantilever,the methods to change the flexibility and to obtain large deformation are discussed.Then three important parameters in the pseudo rigid body model are deduced.An elliptical beam applied to micro-electromechanical system is proposed and analyzed theoretically based on the analysis of compliant mechanism.Equivalent stiffness and deflection of out-of-plane direction of rotation around in-plane axis under moment and force load are derived.Following that,the simulation is carried out by the large-scale finite element analysis software(ANSYS).Then,the theoretical analysis results are compared with the simulation results to verify the validity and accuracy of the finite element analysis method used in this paper.Based on the analysis above,the compliant mechanism with elliptical beam is designed,which can be applied to the driving of microneedle array.The driving displacement and structural strength are simulated by ANSYS finite element simulation software.It is found that there is a functional relationship between the maximum stress and the ratio of the short half-axis b to the minimum width d of the elliptical beam,and parameter optimization is performed by the function relationship.After that,a driving device with four elliptical beam compliant mechanisms in symmetrically distribution is proposed.The driving device in the microsystem is four elliptical beam compliant mechanisms in symmetrically distribution,which are used to drive microneedle arrays,and can be integrated on a chip through microfabrication with microneedle arrays.The strength and displacement of the beams are analyzed and discussed.The influences of the parameters of the elliptical beam on the displacement and stress of the members are analyzed.In addition,as a comparative reference,the micro-systems with the straight-beam driving device distributed symmetrically with the four straight-beam compliant mechanisms of the same size parameters were compared and analyzed,and their advantages and disadvantages were analyzed and discussed.The results show that the new driving mechanism proposed in this paper has obvious advantages in the simulation of driving the microneedle array,and the driving displacement generated is about 1.8 times that of the straight rod driving device.Finally,the micro-processing technology of the transdermal drug delivery system with micro-needle driving device was studied,and the fabrication process are arranged,and the key technologies of process are analyzed and discussed.