Research On Microparts Transfer Methods And Experiments Based On Single Probe And Auxiliary Droplet

The parts of microelectromechanical systems are becoming smaller, and the system structures are becoming more complex and precise. Subsequently, the conventional transfer tools based on mechanical gripping and vacuum adsorbing tend to deform or even destroy the surfaces of microparts. Therefore it is critical to explore a harmless method to transfer microparts.In order to transfer microparts below 100μm scale, a novel microparts transfer method with the function of microforce sensing has been proposed in this paper. The feasibility of the method has been analyzed based on the capillary interaction mechanism, and been verified by the static and dynamic simulation of microparts transfer process. Microparts can be transferred effectively on the corresponding experiment system.Firstly, the microparts transfer method based on a single probe and auxiliary droplet has been proposed. The relationship between the wetting property and the contact angle has been investigated. The feasibility of microparts transfer based on capillary force has been analyzed. The principle of self-alignment and the restoring force has been discussed. Comparing to the capillary tube, the single probe has been chosen as the tool of microparts transfer. The method dipping in droplet has been chosen as the way of micro liquid obtaining at the end of single probe. Based on auxiliary droplet, the microparts releasing scheme of double liquid bridges has been set up. The basic operation strategies of the processes, such as the droplet formation, the micropart picking and releasing have been analyzed.Secondly, the static and dynamic simulation models of mircoparts transfer have been established. Based on the accurate method of liquid bridge meniscus, the static simulation models under the system configurations of a power-law particle and a plane, a power-law particle-sphere, a sphere and a plane have been built. According to the JKR adhesion theory, the adhesive contact model between the sphere and the plane has been studied. Influences of related parameters on the performance of liquid transfer have been analyzed. The feasibility of microparts transfer has been verified with above analysis. Based on the VOF model of multiphase flow, the microdroplet obtaining and the microparts releasing dynamic models have been established. According to the dynamic simulations of micro liquid obtaining, a certain quantity of microdroplet can be obtained by adjusting the related factors including the initial liquid volume, the separation velocity, the contact angles etc. According to the dynamic simulations of microparts releasing, the microparts can be released by controlling the volume of the liquid bridge, the contact angles and other related factors reasonably.Finally, the micropart transfer experiments platform based on the single probe and the auxiliary droplet has been built. The dynamic capillary force during microparts transfer can be obtained through the microforce sensor. The ability of obtaining microdroplet can be adjusted through changing values of the separation velocity of the probe, the substrate material and the initial liquid volume. The performance of microparts picking operation is determined by the feature sizes of microparts, the substrate material and the liquid bridge volume. The accuracy of microparts releasing can be enhanced through decreasing the volume of auxiliary liquid. The feasibility and effectiveness of the method based on the single probe and auxiliary droplet have been verified through the transfer experiments of microspheres with diameters of 20μm, 40μm and 75μm.