Acoustic drop ejection

Noncontact Acoustic Drop Ejection of 2.5-500 nL compound DMSO solutions from source to destination plates for cherry-picking or dose-response series... 

Acoustic droplet ejection Acoustic levitation of droplets Acoustic particle concentration Drop on demand Droplet manipulation Droplet transport by surface acoustic waves Radiation pressure Surface acoustic waves... 

Acoustic waves in liquids can give rise to so-called radiation pressure forces that can in turn drive acoustic streaming flows, deform fluid-fluid interfaces to generate droplets, or exert levitation forces on suspended drops or particles. This contribution reviews three technologically relevant examples of these effects acoustic droplet ejection, droplet transport along a solid surface using surface acoustic waves, and acoustic levitation of droplets. 

Figure 6.9 Pressure required to form and eject an ink drop in inkjet printing. The acoustic pressure generated by an actuator must overcome the viscous pressure drop required to force liquid through the nozzle (frictional energy loss), the surface tension pressure rise to form the drop (surface energy), and the dynamic pressure (kinetic energy) of the liquid.

The acoustic pressure that is required to eject an ink droplet is shown schematically in Figure 6.9. To eject an ink drop, the acoustic pressure that is generated by the electrostatic actuator must overcome the viscous pressure drop required to push the ink through the nozzle ( 0.5-1 atm), the capillary pressure drop due to surface tension ( 0.1 atm), and the dynamic pressure of the liquid associated with its kinetic energy ( 0.5 atm). The total acoustic pressure required to eject a drop will be on the order of 1-2 atm of pressure. 

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