15 January 2016

Aktive Arc Ultrasonics Group delivers key technical solutions enabling uniform nanoparticle surface coating of medical materials.

Our client, a medical devices manufacturer, presented two challenges: 1) make uniform dispersion of nanoparticle in a liquid and eliminate agglomerates; 2) improve spray coating of the nanoparticle loaded liquid.

Problem 1)

Conventional stir mixing of nanoparticles into the carrier fluid did not provide sufficient dispersion. Even with rigorous and long mixing cycles agglomerations of nanoparticles remained.

Solution 1)

Ultrasonic mixing is a well-known and proven technology for dispersion of nanoparticles in a liquid. We designed a custom and proprietary ultrasonic mixing flow cell as a final mix stage that allowed continuous processing and delivery to the atomizing assembly. In this application a high intensity sonotrode with a diameter of 30 mm was used. Such sonotrodes can provide a combination of strong cavitation on the end tip and along the side surface.

Problem 2)

Conventional air pressure spray nozzles do not offer sufficiently small droplets for this application and the air pressure spray system creates a wide spray pattern resulting in significant overspray and wasted material.

Solution 2)

Ultrasonic atomizing is a very efficient technique for making an extremely low pressure spray with a focused pattern and the particle size can be targeted by using an appropriate ultrasonic frequency. When sufficient vibration amplitude on the end tip of the sonotrode is achieved a liquid applied to the tip will atomize on contact. The resulting atomized cloud of droplets has extremely low pressure and the cloud pattern can be customized by shaping the sonotrode tip. Depending on the ultrasonic system frequency the atomized liquid can have a target particle sizes in the range of 15 micrometers to 100 micrometers.

The delivered system met the client’s requirement for nanoparticle dispersion and target spray particle size in a spray pattern that significantly reduced material waste.

© Aktive Arc Sarl 2015