Imagine, in place of a screen door, a thin membrane that would keep mosquitoes out--but would allow human beings to pass through it. Imagine a membrane stretched across your toilet that would allow poop to drop through it, but would prevent gaseous odor from traveling upwards. To create either of these things you'd need a filter that allows large things to pass through it while blocking out smaller ones. That is impossible to achieve by solid, mechanical means--but not impossible if one were to use a self-healing, liquid-based membrane.

That's precisely what a team of researchers at Penn State have accomplished. While the screen door example above is still impossible, the toilet thing is actually within reach, because they have developed a membrane that does what you see below:

Thus far the potential applications they're listing are:

- Insect and particle barrier
- Self-cleaning, nonfouling membrane for continuous particle separation
- Surgical film
- Gas/odor barrier

Readers: Any ideas for additional applications?