Like blooming flowers: this is how the air bubbles formed during the production and transport of viscoelastic substances such as vaccines and oil explode, causing a loss in product quality. To reveal this mechanism, invisible to the human eye but problematic for the industry, are the images captured by the high-speed cameras of the researchers of Stanford University, who together with those of the Federico II University of Naples have developed computational models that will help counteract the phenomenon in the real world. The results are published in the journal of the American Academy of Sciences (PNAS).
Air bubbles can explode in different ways based on their chemical and physical properties: one of these is viscoelasticity. "Many materials around us are not perfectly liquid like water or oil, and they are not even perfectly elastic like rubber: they are somewhere in between," says Gerald Fuller, coordinator of the study together with Pier Luca Maffettone, of 'University of Naples.
The bubbles that form in these viscoelastic materials deform and burst in a different way from classic soap bubbles, but "with our eyes we can't see how the hole opens when the bubble bursts, we simply see it vanish", explains Daniele Tammaro, PhD student of the Neapolitan university at Stanford.
To better study the phenomenon, the researchers examined the bubbles that form in a protein solution (typical in the pharmaceutical industry and in cell culture bioreactors) and popped them with a needle, shooting the scene with cameras 300 times. faster than the human eye, capable of capturing 20,000 images per second. In this way they found that bubbles in viscoelastic materials open like buds, with the outer surface splitting into many petals. The completely unexpected result was translated thanks to mathematics into computational models that could be useful in various sectors, such as the production of drugs and vaccines and the transport of oil.