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By stephan d
This idea is a spillproof bottle cap for young children. It replaces the existing cap on off-the-shelf beverages. The bottle with this cap in place will not release its contents unless a vacuume is present in the nossle (by sucking), so the bottle will not leak from being squeezed. A valve opens with the action of this vacuume.

Reward: impress my mother-in-law
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By FlatTop808
Why not just buy a sippy cup?
By stephan d
It's cheaper and more convenient, I still buy sippy cups. :~(
By just me
They actually sell bottles which have this type of device in them. I believe they are Gatorade or some other sport drink. (And maybe it's just up here in Canada?). Basically the opening has a clear rubber valve which has an x cut in it. When you drink from it, it opens, but when you tilt the bottle upside down, no spill! Very similar to the valve in sippy cups (I have a toddler), but without the secondary air hole.

p.s. very funny, I tried to put, "when you s.u.c.k. on it, it opens" but the computer thinks I was trying to say "hey you, you s.u.c.k." so it wrote *bleep*. Very funny...
By Rishi
There is a catch in what Stephan wants. Sippy cup works when there is a suction applied on the nozzle but does not leak if the bottle just tips over. When there is suction there is a good pressure differential across the nozzle and the juice flows out. There is very little pressure differential when the bottle tips over. So no spill occurs. But what is now demanded is that if the bottle is squeezeed it shall not leak. Under this condition there is a pressure differential across the nozzle. It would leak. What maay have to be designed is some way of using the positive pressure created by squeezing to close the cap.

An interesting puzzle.

By just me
or, just make the bottle ridgid (like a sippy cup) and it won't be squeezeable! Just a thought!
By Rishi
just me is right.

But one can consider an alternative. There are some intravenous drug infusion sets, which have an interesting valve. Polyethylene is slightly less denser than water and so floats on water. It is quite inert and so food and drug compatible. The infusion set has a ball or disc(depending on maker) floating in a sort of cage on the outlet at the bottom. So long as there is fluid flowing out, the valve remains open. The moment the liquid is dained fully and the chamber is nearly empty(except for a few drops), the valve closes preventing air from getting into the veins, which can be fatal.

It should be possible to use this concept suitably adapted for a bottle cap. It should not add much to the cost.

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