Method for detecting EHD injection instability caused by pulse liquid supply of injection pump

Abstract

The invention discloses a method for detecting EHD injection instability caused by pulse liquid supply of an injection pump. A device for realizing the method comprises the injection pump, a controller, a nozzle, a collector, a scattered light collection and detection module and a data acquisition end, a laser of the scattered light collection and detection module emits light beams, and if it is observed that micro-droplets penetrate through the light beams, scattered light is generated at the moment. According to the detection method, data are collected through a photomultiplier tube, the amplitude ratio of frequency components of the data is calculated, and the EHD injection instability caused by pulse liquid supply of an injection pump is studied. Compared with a traditional high-speed camera shooting and image processing method, the method does not need a high-speed camera, so that the corresponding equipment cost is reduced, processing of a large number of images is avoided, the data processing time is shortened, and real-time detection is easier to achieve. Every time micro-droplets are sprayed out, the micro-droplets can penetrate through the laser beams, so that scattered light is generated, and detection and collection of the micro-droplets are more accurate.

Description

technical field [0001] The present invention aims at the problem of jetting instability caused by the pulsating characteristics of the supply liquid flow rate in an electrohydrodynamic (EHD) microdroplet jetting system. This pulsating liquid supply is caused by the stepper motor drive of the syringe pump. The invention proposes a detection and evaluation method of EHD ejection instability based on scattered light measurement, and belongs to the field of droplet generation technology and detection technology. Background technique [0002] Droplet jetting technology is a non-contact micro liquid material application technology, which has the advantages of wide application range of materials, sample saving, non-contact, etc. It is not only used in traditional inkjet printing, but also widely used in medicine and bioengineering, 3D manufacturing. , integrated circuit board printing and other important fields. Common droplet generation technologies are based on thermal actuatio...

AI Technical Summary

Problems solved by technology

[0007] The most direct way to detect the state of micro-droplet ejection is through high-speed camera and image processing, but this method has disadvantages

On the one hand, high-speed cameras are very expensive; on the other hand, processing a large number of images is very time-consuming, which is far from achieving the purpose of real-time monitoring of injection status

While the EHD droplet jetting method can produce droplets with a diameter of tens of microns or even smaller, imaging requires a considerable magnification, and the field of view will be small, so clear and stable imaging is not easy, because some droplets may deviate from the vertical drop trajectory

In addition, imaging is done with a backlight configuration, placing the nozzle between the camera and the light source, and for very small droplets, the contrast between the droplet and the background is poor, making it difficult to extract the edge of the droplet

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