Antimicrobial Coatings using Ultrasonic Spray Nozzles
Ultrasonic spray technology is used to apply antimicrobial spray coatings for a variety of industries from medical, food, textiles, electronic devices to construction materials. Ultrasonic spray technology is ideally suited for applications that require low dosages of antimicrobial formulations to be uniformly applied to a surface. Good examples are silver, copper and zinc oxide, zirconium, Zinc Omadine® (zinc pyrithione), gold nanoparticles and titanium dioxide based antimicrobial materials used as colony inhibitors in textiles, medical catheters and other surfaces.
Silver nanoparticles for example is an expensive material and manufacturers require precision dosing with little or no waste. The spray plume from an ultrasonic spray nozzle can easily be shaped and the velocity of spray precisely controlled. If coating a catheter, an ultrasonic nozzle typically with a narrow spray pattern with low velocity will be utilized. In contrast, an array of ultrasonic nozzles with a vortex configuration running at higher velocities will be used for coating textiles. Both configurations maximize the transfer efficiency of coating material, keeping waste to a minimum while maintaining manufacturing throughput requirements.
Antimicrobial Spray Coatings in the Food Industry
Unlike medical, textiles and construction materials that largely use silver based antimicrobial coatings formulations, the food industry utilizes a variety of FDA approved formulations for treating a wide variety of food products. For example, in the meat industry, Lauric Arginate (LAE) is widely used in ready to eat meats (RTE) as an antimicrobial in low dosages during the manufacturing process. When LAE is used in very low dosages, the FDA considers the antimicrobial as a “Processing Aid,” thus exempting it from final consumer product labeling. Ultrasonics spray nozzles can precisely dose RTEs with micron level accuracy and high uniformity, maintaining FDA requirements and labeling exemptions. In the baking industry ultrasonic spray technology is used to spray potassium sorbate to inhibit mold formation. Ultrasonics minimizes waste of potassium sorbate, but also the amount of material released to the environment as emissions.
The FDA lists several dozen approved antimicrobial coatings materials and formulations currently applied as sprays, such as the family of sodiums (benzoate, diacetate, propionate, hypoclorite, octanoate). A number of acids such as propionic, acetic, sorbic, citric and lactic. Also listed are numerous blends such as lactic, citric acids with potassium hydroxide. Finally bacteriophage preparations, carnobacterium and lactoferrin are sprayed onto food products as an antimicrobial. It is not known at this time if any of these materials have been sprayed with ultrasonic nozzles, but the robust construction of our ultrasonic technology and the fact that live microbes have been atomized, lends us to think many of these chemistries are sprayable with ultrasonic spray technology.