| abstract |
A non-mechanical valve and/or filter device (37) which is suitable for use in an apparatus for aspirating body fluids (14) and which comprises a water insoluble, water-absorbent material which, upon contact with water, becomes substantially impervious to flow through it of gas and liquid in the wetted regions thereof, the preferred form of said device being a porous rigid structure of sintered particles of polyethylene and said water-absorbent material. |