How do ultrasonic waves kill microorganisms?

Answer 1

Yes, they can. But they're not that good at it. There are basically three variables in ultrasonic sterilization: frequency of the ultrasonic signal, untrasonic field intensity and exposure time. A frequency of about 25 kiloHertz works pretty well. Higher is not better. Lower and people can hear it. The other two variables are pretty much self-explanatory. Let's be clear about the fact that ultrasonic energy is not ionizing energy. It will not "break" chemical bonds in the normal sense. In sonochemistry, we see that ultrasonics have interesting effects on the rate of chemical reactions, but there are limits on what can be done. Let's look at mocroorganisms. Little critters have membranes around their "bodies" as such, and the ultrasonic cavitation acts on this. Actually the inner membrane (the cytoplasmic membrane) is usually the target. The miroorganism's lipoprotein bilayer is disrupted and the little critter dies. (The layer is torn, shredded or something like that - the exact nature of the disruption isn't clear.) Note that the cavitation damage to the vulnerable structures must be "extensive" enough to be fatal. A "little bit" of damage won't kill the microorganism. That's where the field intensity and the time of exposure come in. Make sense? It's not rocket science. Ultrasonic cavitation causes heat. That is a separate issue with ultrasonics as applied to "sterilization" (which cannot be achieved). Why use ultrasonics to heat something? Just autoclave it. Yes, ultrasonics can heat things really hot if field intensities and exposure times are long enough, but it isn't very cost effective. The use of ultrasonics to destroy microorganisms is usually considered out of a desire to avoid heating something. Ultrasonics won't kill a virus. The non-life forms have a "purely chemical" structure, and are unaffected by the direct application of ultrasonics. (Again, the heat issue is set aside. Focus on the ultrasonics.) Mold spores cannot be deactivated by ultrasonics. There are a lot of drawbacks to using ultrasonics to "clean" and to "sterilize" areas. It isn't all that good. But research is continuing. And Europe leads the league in the medical investigation of ultrasonics at last word.

Answer 2

I believe ultrasonic (and basic sonic) characterisitic which can and does work (not FDA officially approved and doubtfully clinically trialed) is resonance. You know, Cartoons, Disney movies when Opera singer hits a note and the glass breaks... that's the resonant frequency, happens to be the one given off when you tap the object (glass in this case). Played back at the optimal time when a previous waves excess energy is starting an echo cycle, AND the input signal is delivering its next wave, a surplus is created... at 75Ghz that surplus happens 75Billion times in a second, that objects calamity is greatly altered, if scope is on target avoiding collateral error, increase intensity ineffective virus (if you couldn't kill it that much shaking would make docking to a cell receptors less successful if even possible while in that state... More complex than this but, it's physics, system tolerances especially those characterized with complexity that only by debatable definition falls short of being "living", can't ignore a distraction (ideally a fatal incapacitating one) due to the physical vibration 75 billion times stacked energy of the echo wouldn't make evolutionary sense. If your answer is still "probably still a safe enough shaking" then mine is "NO you can't babysit my newborn" :-O. Targeting is likely the hardest part, overall resonance, constituent resonance, molecular resonance etc... Probably a neural network away from some hard to fathom breakthrough, that plus the inhibiting FDA's 1Billion Dollar clinical trial requirement... Putting up that amount to fund a tech that could fix most known viruses, not smart for the medical treatment industry, not a conspiracy but kinda better to not bring up in a board meeting, unless you like the basement, a missing red stapler and don't need paychecks in a timely manner.

Answer 3

to squeeze a gas ito a smaller space