Abstract: An osmometer for use in the measurement of gases, liquids and solids is disclosed. The osmometer includes a semipermeable hollow fiber, capable of passing liquids but not dissolved solids. The hollow fiber contains a media component with a predetermined osmolarity compatible with the sample to be measured. A gas volume is also contained within the hollow fiber and a sensor is present and located adjacent to the gas volume. The sensor is responsive to changes in the gas or media volume due to changes in the media component caused by the influx or efflux of water to the hollow fiber.

Abstract: A hollow fiber formed of hydrophilic material and having permeable walls is treated to enhance the permeability. Reactions used to treat the fiber have a gas inside and gas outside, a gas inside and liquid outside, a liquid inside and gas outside, and a liquid inside and a liquid outside. The treatments generally involve the plasticizing of the fiber material while having the inside of the fiber at a higher pressure than the outside. These treatments produce a structural change in the fiber from a flexible tube having strong walls to expanded, rigid and somewhat fragile walls. Where more than a short length of the treated fiber is to be used, an open mesh cage is used to confine the fiber to a desired volume during treatment and to protect it subsequently. A technique for joining flexible tubing to the treated fiber is presented. The treated fiber may be used in apparatus and methods involving osmosis and reverse osmosis.