Plastic Disc with one sided opening (one sided valve)

We are looking for a flat round hard plastic in a disc shape. Having opening (like a valve on the hard plastic disc) on one side of the disc only. This Disc will be placed between two chambers sitting on top of each other (chamber 1 bottom, chamber 2 top) within a bigger vessel/container. Upon tilting the entire vessel or container (originally, standing up vertically in 90 degrees) in clockwise direction (towards 180 degree), the liquid (water consistency) residing in chamber 1 will flow through the opening (valve) in the hard plastic disc into chamber 2 in one direction only without contaminating (zero contamination) the liquid residing in chamber 1. Once liquid reaches chamber 2 we should be able to bring back the entire vessel/container back to it's original position (Standing straight up in 90 degree) and this disc will not let any liquid in chamber 2 from flowing back into the direction where original liquid resides (chamber 1), so no cross-contamination. The thickness of the plastic disc should be as flat or should be as minimal as possible. Preferably the thickness should be 1/8 inches or less in most of the area of the disc and can be thicker (preferably up to 3/4 inch maximum) on the area where opening/valve will exist (from which liquid pours through from). Container/wrapper/vessel within which the disc is placed is non-pressurized and would be completely closed except for an opening in the top of chamber 2. Again we do not need to worry about chamber 2 openings. All we care about is this disc with some type of opening (valve) between chamber 1 and 2 must be able to have the liquid pour out from chamber 1 into chamber 2 and not let any liquid back into chamber 1. Their can be no cross contamination, once the liquid pours into chamber 2 it may be mixed with another liquid before exiting from chamber two. This hard plastic disc would function something similar to a check valve. If the entire vessel or container is shaked vigorously, none of the liquid from second chamber can enter the first chamber. Volume of liquid in chamber 1 is dynamic (It can be full or half way initially. Upon tilting it could be the case we pour out all the liquid from Chamber 1), Volume of liquid in chamber 2 is dynamic as well (it can be empty or their can be some liquid already in chamber 2), and vessel/container will always be of a cylindrical shape. Diameter of disc can be flexible. Initially, we can have the diameter of the disc to be 2.5 inches. I am looking for someone to design the prototype of this product. I prefer if you submit drawings or a brief explanation with your Bid on how this will be achieved. Especially, mentioning how a cross contamination will be completely avoided.