A fluid membrane, developed by mechanical engineers at the University of Pennsylvania, is well defined as "straight out of science fiction." Its peculiarity is that it allows large objects to pass through itself, blocking smaller ones.
The principle of operation of membranes is in many ways similar to filters and an ordinary colander. For example, if you fill a kitchen colander with peas and castor sugar (sugar dust), and then shake the mixture well, then it is quite expected that sugar will sprinkle through the holes, and the peas will remain inside.
Scientists from the University of Pennsylvania set themselves a seemingly unrealizable goal - to create an anti-filter that will allow larger objects to pass through, and leave smaller ones outside. As it turned out, this effect can be achieved using a liquid membrane.
In liquid membranes, everything happens a little differently: larger and heavier objects with greater weight, "pierce" it, and the "trifle" remains outside. As a result of experiments with water and various solutions of alcohols, scientists came to the conclusion that the best liquid membrane is a soap film on the surface of the water.
According to researchers, such "anti-filters" will find their application in surgery. Imagine that the part of the body on which the operation is performed is covered with a special compound, a self-healing liquid membrane, through which surgical instruments are inserted into the wound. At the same time, it reliably envelops the site of penetration into the wound, and pathogenic microbes remain outside.