Droplet generator, calibration

H. Ulmke, T. Wriedt, and K. Bauckhage Piezoelectric droplet generator for the calibration of particle-sizing instruments. Chemical Engineering and Technology, 24(3), 265-268 (2001). 

Electrical methods involve the detection and analysis of electronic pulses generated by droplets in a measurement volume or on a wire. The electronic signals are then converted into digital data and calibrated to produce information on droplet size distribution. A detailed review of electrical methods for droplet size measurements has been made by Jones.[657]... 

The final implant annealing process schedule developed during this research is shown in Figure 4.19. A 6-slm UHP Ar flow is first established in the reactor. When the RF generator is turned on, the susceptor is heated to the annealing temperature (typically 1,600°C) using a controlled thermal ramp. To avoid the formation of Si droplets, silane is not introduced into the reactor until a substrate temperature of 1,490°C is reached. At that time the premixed silane in Ar gas is introduced into the Ar carrier flow at a flow rate of 20 seem. All flows are controlled using calibrated... 

The airbrush needle and propellant gas pressure are adjusted to generate droplets of the appropriate size without shearing the cell or nucleus. An ink-glycerol mixture sprayed onto a pool of liquid on a glass slide, and measured, provides a convenient initial calibration. Fine tuning is done by spraying the actual sample onto a slide to make adjustments for viscosity and concentration. For isolated chicken erythrocyte nuclei, a pressure of 102 kPa produces 10-jum droplets, whereas whole cultured fibroblasts require a pressure of 81.6 kPa to provide 50-/im drops. 

The fields of applications of droplet stream generators are predominantly research and development [43—48]. They are typically used for investigations of transport phenomena with liquid drops, where the good control of the drop size provides a means to adjust initial or boundary conditions of the process. Examples are evaporation of droplets and their transport in gas flows. In the development of new sizing techniques for liquid droplets, the availability of a calibration or validation standard is essential. Drop stream generators were important experimental means for verifying... 

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