breaking the surface tension of a droplet within a tube

Farnet

Hi,

I wasn't actually sure where I should post this.

I am trying am experiment where I need to briefly break the surface tension of a droplet to then allow another droplet to form in it's place.

I don't want to use any chemicals as that would effect the test further down the line.

Is there an element that will naturally break the surface tension of water when it is briefly in contact with it?

Basically I can get the water to form a droplet just inside the tube (which is 0.8mm ID) with a concave surface at the end of the tube, but due to its size it will then just sit there (so to speak), and I need it to drain from the tube without using any increased pressure or chemicals....

I have thought of wicking, but that is way too slow (tested it and it does work), although I have been informed that silica strands are far better.

Any help is appreciated.

Cheers

Farnet

Farnet

Just to make it a bit clearer.

I am using capillary action to draw the water horizontally to the end of the tube and even with the tube pointing slightly down there isn't enough force for the water to drip out.

I had a light bulb moment and thought that if I can somehow break the surface tension at the end of the tube, then it might act like a dripping tap.

I don't want to contaminate the water, so I am looking at any way that I can achieve this with no chemical, electrical or mechanical intervention, I have been searching the net for various ideas but I am getting nowhere.

Apologies to those of you who are thoroughbred scientists, this is my pet project and as such not a professional, just budding enthusiast :-)

Farnet

I have to say i'm quite surprised no one here has a clue, I was advised to post here as you guys should know the answer, I'll try the physicists...

chemisttree

I would use a product used to treat bathroom mirrors an render them "fog free". Rain-X makes one.

Farnet

Ahh, now thats a good idea.

Thanks Chemistree :-)

chemisttree

I don't know if it will work but it is a cheap way to see if you are on the right track. The use of silica whiskers is a good idea and it actually might be those that you want to treat rather than the tip of the capillary.

Alkim

Or just use a drop of alcohol.

chemisttree

And not contaminate the water? If you are one of those that believes that alcohol should never be classified a 'contaminant', welcome to my club.

VACUUMIST

Hello

Did you mind of electrocapillarity?
May be that a wire at high potential will modify the surface tension doing what you need.

Roberto