Design And Experimental Study Of Striker-type Droplet Ejection System

Micro droplet injection technology is a kind of technology that uses external force to make liquid eject from the nozzle in the form of micro droplets.This technology has the advantages of high resolution,wide frequency range,high control accuracy and wide range of spraying materials.At present,the technology has been widely used in biomedical,mechanical manufacturing,microelectronic engineering and other fields.In this paper,based on the impact pin structure,the electromagnet is selected as the driver,and a micro droplet injection system with simple structure,flexible and controllable parameters and stable injection is designedThis paper analyzes the working principle and the process of droplet generation of the impact pin micro droplet injection system,analyzes the cause and process of satellite droplet generation during the injection process,and calculates the flow,jet formation and substrate deposition of the fluid in the micro nozzle.The system is composed of five parts: micro droplet spraying device,electromagnet and driving control circuit,bracket,movable platform and micro observation module.Among them,the micro droplet spray device is the core device to realize the spray forming of droplets.The structure of the micro droplet spray device is designed,the glass micro nozzle is made,and the electromagnet driving control circuit is designed.The dynamic model of the micro droplet ejection device is established,and the impact process of electromagnet and striker descending and the stress analysis of the crossbeam are completed.In this paper,the process of droplet injection and satellite droplet generation is simulated by using Comsol multiphysics software,and the effects of solution viscosity and nozzle diameter on droplet generation are studied.In this paper,the micro jet system is developed,in which glycerin water solution with different volume fraction is used as micro jet liquid.The system parameters mainly include driving voltage,driving frequency,micro nozzle diameter,electromagnet stroke and viscosity of the jet solution,which affect the micro jet quantity and stability.The experimental results show that the stable injection and volume control of droplets can be realized by reasonably controlling the parameters of the system,and the viscosity of the injected droplet can reach up to 1410 mpas,fhe minimum volume can reach 0.1 μl.