Portable oxygen concentrator

Abstract

There is provided a portable oxygen concentrator. The portable oxygen concentrator comprises a sieve bed comprising an inlet and an outlet; a first region of adsorbent material adjacent the inlet; and a second region of adsorbent material adjacent the outlet. The first and second regions of adsorbent material comprise beads of adsorbent material. The first region comprises beads of a first size and the second region comprises beads of a second size which is larger than the first size.

Dependencies are inferred from the claim text.