US Patent 7281670 Wick-based delivery system with wick made of different composite materials

A wick-based delivery system includes a container for holding a liquid that has an opening therein. A porous wick is positioned in the container so that a lower region of the wick is in contact with the liquid in the container and an upper region of the wick is exposed to the ambient air. The porous wick has discrete inner and outer concentric cylindrical sections, the inner cylindrical section being made of a sand-based material and the outer cylindrical section being made of a plastic material.