Automated fluid dropper

Hi,

I want to release droplets of water one-by-one on command, and have been doing some research on how to do that, but I'm wondering if anyone has some other ideas or has heard of a ready-made solution.

So far I have come across:


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-peristaltic pumps with really low flow rates, like the one here

http://aptinstruments.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=AI&Product_Code=SP100VO&Category_Code=

It goes down to 0.09 ml/minute, which should be small enough. I can selectively turn the pump on and off, feeding water to a small tube or dropper end, producing the water drops. These are pretty expensive, the cheapest one I've seen is around $60.


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-DIY systems like the one pictured here
with a solenoid opening and closing a safety pin on a tube.

http://www.maggiecarsonromano.com/index.php?/projects/what-made-the-wound-wound-the-thread/

Maybe I could tune the distance of the solenoid so it just opens the pin a tiny amount, and a drop or so is allowed through.


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-or I could use a more typical water pump, attach it to something with a really small aperture. I could turn the pump on and off. I have a hard time picturing drop-by-drop control with this, I might be able to release very small amounts, and maybe some 2nd reservoir between the motor and dropper could be designed to aid this.


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Is there a ready-made solution to what I'm trying to do? If I just get a regular water pump what should I look for? Ideally I'd like to get a pump that's as quiet as possible, too.

Thanks bros.
Josh
 

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CameronSS6 years ago
Simplest thing I can think of is a syringe with a worm screw pushing down on the plunger, rather like a c-clamp. A gearmotor or servo might run slow enough that you could just let it run, or with a very simple DC motor controller. Something like this.
Could one use a screw type mechanism to "move" the water (the screw being on the inside of a tube like enclosure) where it would lift only a drop or so of fluid in each "turn"?
Archimedes' screw! I don't know how scalable that is, since they're generally used to transfer large volumes of water, but I like the idea. Something like a length of all-thread in a close-fitting copper tube might work.
Archimedes_screw.JPG
yes, I was thinking of a less angled screw for moving maybe smaller amounts (if the tube was also small.
And an Archimedes' screw typically has very broad threads compared to the central shaft size, because they're trying to move as much water as possible. Threaded rod has very narrow threads relative to the shaft, so it would be much slower by nature.
Pncgs6 years ago
You might consider using a syringe pump and a controller. Google "syringe pump" for ideas.
The peristaltic is probably the most sensible method. I've seen small pumps for much less than 60 USD on Ebay.

Steve
a peristaltic pump should be pretty easy to make DIY like anyway. all you need is a motor, an oblong (or at least a circle with a bump) piece of material, and a housing. they work by turning the oblong piece within a circular housing. as the oblong piece comes around to the part of the housing that's closer to the tube, it pinches the tube and pushes the liquid through the tube which in turn sucks more fluid up to fill in the gap.
djdune (author) 6 years ago
i think what i'm looking for is one of these
http://en.wikipedia.org/wiki/Solenoid_valve
in conjunction with gravity or a pump that's always on.

here's a cool artwork: http://www.zehao.com/works/2005aqueous/?show=details
Jayefuu6 years ago
At what rate?
Does the rate vary? And if so...
What's the minimum rate?
What's the maximum rate?
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