Had a crazy thought. I'm sure you're all aware of the static/running water experiment. I'm envisioning a positively charged screen to repel aerosol/droplets from passing through the grid powered by a battery. Obvious application as a mask against pathogens such as the one we're presently up against. Is this possible? It doesn't need to be any more powerful than stopping anything getting past the grid.
Since I have no idea of the strength of such a repellent force, I cant comment on whether this would work only in a still-air case, or when subjected to the force/flow of someone's breath. Off hand I'd guess that such an electrostatic force would be no match, but I really dont know. Somebody else?
Well, the simple experiment I referenced exhibits a relatively strong pull. So could this not be reversed with a positive charge instead of a negative one?
If you don't know the polarity of the droplets it's just as likely I would think that you would attract them.
I hope this thread remains civil and on topic.
I hope this thread remains civil and on topic.
Right, but from my understanding, and I stand to be corrected, droplets will always be positively charged?
Not according to the paper in post #2.
"Specifically, when two droplets coalesce, they can spontaneously jump away from a superhydrophobic
surface due to the release of excess surface energy. Here we show that jumping droplets gain a
net positive charge that causes them to repel each other mid-flight."
"Specifically, when two droplets coalesce, they can spontaneously jump away from a superhydrophobic
surface due to the release of excess surface energy. Here we show that jumping droplets gain a
net positive charge that causes them to repel each other mid-flight."
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So the respiratory track of a human being is super hydrophobic and the momentum imparted on those droplets by a cough or sneeze can be overcome by a comparatively weak electrostatic field at the target?
Is the test case discussed applicable to particles that still have significant energy from their launch into the environment.
This might work well at a greater distance?
It's an interesting idea and I assume if it worked reliably would have already been implemented in PPE?
Is the test case discussed applicable to particles that still have significant energy from their launch into the environment.
This might work well at a greater distance?
It's an interesting idea and I assume if it worked reliably would have already been implemented in PPE?
Pete, I can't find any evidence to support your hypothesis that a cough contains aerosol drops which are electrically charged, whether that be positive or negative.
Unless your initial assumption can be substantiated, I'm afraid there is little point in continuing to pursue your idea.
Natural electrification occurs when a droplet separates from a disimilar material like glass, but is unlikely to happen when separating from moistened lung tissue.
If I am wrong, I will be happy to receive any evidence to the contrary.
Unless your initial assumption can be substantiated, I'm afraid there is little point in continuing to pursue your idea.
Natural electrification occurs when a droplet separates from a disimilar material like glass, but is unlikely to happen when separating from moistened lung tissue.
If I am wrong, I will be happy to receive any evidence to the contrary.
A superhydrophobic surface is one that is very difficult to wet. That is surely not a property of the respiratory tract.
I'm assuming naturally positively charged. Did you see my reference to the well known experiment in the op? Without presumption I will describe it here for anyone not aware.
If you hold a statically charged object, say a balloon you've rubbed on the carpet or a comb, styrofoam cup etc. close to a slow stream of water coming out your kitchen tap, you will observe it drawn/pulled towards the object which is negatively charged. Conversely, the opposite would happen if the charge in the object were reversed. It is this phenomenon I was contemplating.
The respiratory tract as pointed out elsewhere (by me and Galu) does not match the described conditions. It's doubtful in my mind (noting that I am not an expert) that the aerosol launched by a cough or sneeze has a charge or perhaps non-arbitrary charge on it. The human respiratory tract is very wet, and presumably any charge present on the aerosol would have to be that of the launching human being?
Given the widespread use of electrostatic filters and precipitators I'm assuming this would already be in use in PPE if it worked..
I used to own an electrostatic filter and it's my recollection that it was designed to in such a way to impart a charge to particulate matter using charged screens so that it could be attracted to the charged plates. (It had a large fan and post filtration in addition to the electrostatic filter - worked well until the HV supply died. I always had the suspicion it was making a bit more ozone than the amount claimed which is a respiratory irritant)
Given the widespread use of electrostatic filters and precipitators I'm assuming this would already be in use in PPE if it worked..
I used to own an electrostatic filter and it's my recollection that it was designed to in such a way to impart a charge to particulate matter using charged screens so that it could be attracted to the charged plates. (It had a large fan and post filtration in addition to the electrostatic filter - worked well until the HV supply died. I always had the suspicion it was making a bit more ozone than the amount claimed which is a respiratory irritant)
That was my whole point - on what do you base that assumption, Pete?
The experiment illustrates 'charging by induction' or 'charging by being near'.
Electrons are either attracted to the emerging stream of water from earth (via the plumbing) or repelled from the stream of water into the earth, depending on whether the plastic comb (the inducing object) is positively charged or negatively charged.
When the water breaks free from the tap and is collected in a container it will retain its surplus or deficit of electrons and will hence be negatively or positively charged.
Electrically charged water. Who'd a thunk it! Tastes just the same! 😎
P.S. The opposite that you mention doesn't happen when the charge on the inducing object is reversed - opposites always attract!
P.P.S. Such a process won't occur during the production of cough aerosols.
See, here is an example of my level of knowledge.
I did a bit of research. No, the water does not have a charge, it's neutral. But the negatively charged object, when brought near attracts the electrons in the water thus bending the stream towards the negatively charged object. This happens regardless of the source of water...it can be dispensed out of one container into another without a reference to ground. So aerosol particles I'm assuming(hopefully not as Benny Hill does), would be repelled away from a positively charged grid in the same way as well?
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That's not the physics of my universe Pete!
I suggest you actually read my explanation, which is scientifically correct.
I'm outta here!
I suggest you actually read my explanation, which is scientifically correct.
I'm outta here!
I'll just pop back in to include this vital information which I omitted. As long-standing sparring partners, I simply can't abandon you to false physics Pete!
A positive object will induce a net negative charge in the stream of water (by attracting electrons from earth). Since opposites attract, the negative stream is attracted towards the positive object.
A negative object will induce a net positive charge on the stream of water (by repelling electrons to earth). Again, since opposites attract, the positive stream is attracted towards the negative object.
Usually, the water is neutral as you said, but shifting electrons about in this way alters the neutrality in the direction of net negative or net positive.
As Benny said, "Learning all the time."! 😉
A positive object will induce a net negative charge in the stream of water (by attracting electrons from earth). Since opposites attract, the negative stream is attracted towards the positive object.
A negative object will induce a net positive charge on the stream of water (by repelling electrons to earth). Again, since opposites attract, the positive stream is attracted towards the negative object.
Usually, the water is neutral as you said, but shifting electrons about in this way alters the neutrality in the direction of net negative or net positive.
As Benny said, "Learning all the time."! 😉
So apparently there's lots of research going on in the inactivation/capture of virus using ion emitting instruments. In the op I focused on droplets since that is how transmission takes place, however the type of virus we're plagued with presently does appear to have a positive charge. Just having a negative ion generator seems to be an advantage.Ionizing air affects influenza virus infectivity and prevents airborne-transmission | Scientific Reports
Lots of articles if you google..charge of airborne particles.
Lots of articles if you google..charge of airborne particles.
Hope I can contribute: The other night I turned on the hot water before having a shower, went to get undressed, came back to the faucet to check the temperature at the faucet by sticking my finger into the water stream, and ZAP, got the most wicked static shock ever!
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