Question

what is back suction with diagram? ans Plzzzzzz fast

Answer 1

Dispense failure situation: (a) excessive back suction; (b) adhesion; (c) flow-stream; (d) satellite droplets; (e) sputtering. 

Source publication

































Simulation and Experiment on Droplet Formation and Separation for Needle-Type Micro-Liquid Jetting Dispenser

Article

Full-text available

Jun 2018



Shizhou Lu



Guangyu Cao



Zheng Hai

[...]



Jiahui Qi

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Context 1

... can be seen from the above analysis, the needle vibration and the pressure drive achieve the droplet formation and separation, and a successful jetting process should at least satisfy the following conditions: (1) In the backflow stage, the amount of liquid flowing back into the channel should be controlled in a suitable range, otherwise some bubbles may be mixed within the droplet, which might be broken into lots of scattered dots ( Figure 4a); (2) During the droplet growth stage, no ejected liquid remains on the nozzle tip, otherwise the created thick liquid layer will stop the flow ( Figure 4b); (3) During the extension and breakage stage, the jetting speed should also be in a suitable range, otherwise a long stream or satellite dots might appear as Figure 4c-e show. The above abnormal jetting situations are related to the system parameter settings. To effectively guide the droplet micro-jetting process and ensure stable droplet separation, the paper will further study the effects of driving and structural parameters such as air pressure, viscosity, needle stroke and nozzle diameter on the changes in morphologies of droplets. ...

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Context 2

... can be seen from the above analysis, the needle vibration and the pressure drive achieve the droplet formation and separation, and a successful jetting process should at least satisfy the following conditions: (1) In the backflow stage, the amount of liquid flowing back into the channel should be controlled in a suitable range, otherwise some bubbles may be mixed within the droplet, which might be broken into lots of scattered dots ( Figure 4a); (2) During the droplet growth stage, no ejected liquid remains on the nozzle tip, otherwise the created thick liquid layer will stop the flow ( Figure 4b); (3) During the extension and breakage stage, the jetting speed should also be in a suitable range, otherwise a long stream or satellite dots might appear as Figure 4c-e show. The above abnormal jetting situations are related to the system parameter settings. To effectively guide the droplet micro-jetting process and ensure stable droplet separation, the paper will further study the effects of driving and structural parameters such as air pressure, viscosity, needle stroke and nozzle diameter on the changes in morphologies of droplets. ...