Manufactures can customize electrochemical gas detectors by changing the porous barrier to allow for the detection of a certain gas concentration range.

In general, smaller molecules have higher diffusivity, and therefore would move through a porous barrier (like a balloon) faster than larger molecules.

This simpler version dispensed with the porous barrier.

From there it reaches the brain by passing through a porous barrier called the cribriform plate.

A porous disk or other porous barrier between the two half-cells may be used instead of a salt bridge; however, they basically serve the same purpose.

In the laboratory, a Büchner funnel is often used, with a filter paper serving as the porous barrier.

The use of a porous barrier allows ions to pass through but keeps the solutions from mixing.

A porous barrier or ceramic disk may be used to separate the two solutions while allowing ion flow.

But walking through this porous barrier prepares the senses to be stunned by what lies beyond.

If, however, the porous barrier is selective to which ions are let through, then diffusion alone will not determine the resulting solution.