Ultrasonic nozzle

Ultrasonic nozzles are a type of spray nozzle that uses high (20 kHz to 180 kHz) frequency vibration to produce very narrow drop size distribution and low velocity spray from a low viscosity liquid (such as water). The vibration of a piezoelectric crystal causes capillary waves on the nozzle surface liquid film. The primary factors influencing the drop size produced are frequency of vibration, surface tension, and density of the liquid. Ultrasonic nozzles are powered by a generator. A white board showing how basic principles of how ultrasonic nozzles work can be found here: How Ultrasonic Spray Nozzles Work and here: Ultrasonic Atomization.

Ultrasonic nozzle applications

Electronics manufacturing

From applying flux to very precise areas on a circuit board to the application of carbon nanotubes on to touch-screens.

Medical industry

Pharmaceuticals such as Sirolimus (Rapamycin) and Paclitaxel used with or without a polymer is coated on the surface of drug eluting stents (DES) and drug eluting balloons (DEB). These devices benefit greatly from ultrasonic spray nozzles for their ability to apply coatings with little to no loss. Medical devices such as DES and DEB because of their small size, require very narrow spray patterns, a low-velocity atomized spray and low-pressure air^[1] . A variety of nozzle configurations are utilized from direct liquid delivery through the center of the ultrasonic nozzle to external liquid delivery by use of an external hypotube to the nozzle's atomizing surface. Spray width can be as low as 0.015" (0.4 mm) are possible. Soft, low-velocity atomized spray can be targeted with unmatched precision with minimal overspray (minimal waste). Ultra-low flow rates can be achieved over a wide range (from 0.3 - 9 ml/hour). Self-cleaning ultrasonic nozzle can prevent clogging.

Renewable energy

Photovoltaic and dye-sensitized solar technology both need the application of liquids and coatings during the manufacturing process. With most of these substances being very expensive, any losses due to over-spray or quality control are minimized with the use of ultrasonic nozzles.

Nanotechnology

As manufacturing techniques get closer and closer to the atomic level, dipping parts and components in a bath is no longer viable. Extremely accurate spray will be needed more and more as technology shrinks to the point where processes can no longer be seen with the naked eye.

References

Berger, Harvey L. Ultrasonic Liquid Atomization: Theory and Application. 2nd ed. Hyde Park: Partrige Hill, 2006. 1-177.

Lefebvre, Arthur, Atomization and Sprays, Hemisphere, 1989, ISBN 0-89116-603-3