Research On Micromanipulation Method And System Based On Capillary Action And Liquid-filled Micropipette Spitting And Swallowing

Contemporary techniques for micromanipulation can be roughly classified into the robotic pick-and-place and the self-assembly.However,the pick-and-place strategy is intrinsically a serial process,resulting in the low manipulation efficiency.And the self-assembly is somewhat inflexible owing to the fact that it relies on the fixed templates.Thus,to meet the requirements of the micromanipulation in many fields,such as MEMS,optical imaging,it is critical to present a micromanipulation method with both operational efficiency and flexibility.Combining the traditional pick-and-place and self-assembly approaches,a method for micromanipulation based on capillary force termed liquid-filled micropipette spitting and swallowing has been presented.And the corresponding micromanipulation system has been built on which could manipulation micron-sized objects(ten to several tens of microns)with high efficiency as well as flexibility.Firstly,the micromanipulation method has been divided into three parts: the alignment of micro-objects,reliable release and flexible pick up.The three processes has been respectively analyzed theoretically,including the influence of parameters on the efficiency of micro-objects alignment,mechanical analysis of release and pick up process.In addition,based on the Young-Laplace equation,established the release and pick up model of capillary action,obtained the surface profile of the liquid bridge during release and picking and analyzed the influence of capillary force via static simulation analysis.Secondly,the micromanipulation system based on capillary action and micropipette has been built,which includes a motion module and an optical microscopic visual module and a micro-manipulator.And the micro-manipulator is consists of a funnel shaped micropipette,a pressure regulating equipment and a vibration unit.The micromanipulation control strategy based on microscopic visual feedback is studied,including the control strategies for automatic release and pick up,the image recognition and positioning of the manipulator and the micro-objects,extraction of critical information in release and pick up process,which provides a theoretical basis for improving the degree of automation of the system.Finally,the experimental studies on the three parts of the micromanipulation method have been carried out on the basis of the micromanipulation system.Experimental results showed that the efficiency of micro-objects alignment is greatly influenced by the concentration of micro-objects suspension and the rate of liquid volatilization.The vibration unit can effectively solve the clog problem caused by adhesion.Regulating the pressure difference and the substrate contact angle can be applied to ensure the success of release and pick up.The release manipulation can reach a relatively high positioning accuracy about 2.1±0.41 ?m when coordinating the pressure difference,micropipette inner diameter and the contact angle.The self-calibration experiment showed that under certain conditions,the method can pick up the misaligned micro-object.In addition,microscopic visual inspection experiments were performed to obtain critical information during release and pick up,providing the basis for automated micromanipulation.The feasibility of method and the effectiveness of the system were verified by some micromanipulation examples.