NOVELTY - A fuel storage and delivery device for transferring a first liquid into a second liquid of different substance(s), comprises a wick wetted by first liquid and positioned in siphon fashion with a first portion contacting the first liquid and a second portion contacting the second liquid. The penetration rate of the first liquid in the wick is faster than that of the second liquid in the wick, thus a net amount of the first liquid is transferred into the second liquid.    USE - The fuel storage and delivery device is used for transferring a first liquid into a second liquid of different substance(s) at small flow rate, liquid-feed fuel cell system (claimed).    ADVANTAGE - The permeability of a wick generally depends on the external force that is applied to the wick, and can be adjusted through adjusting the compression force upon the wick. The control of the fluid flow through the wick is easily achieved through a flow control pinch valve that is mounted on the wick. The fuel storage and delivery assembly directly utilizes a liquid fuel without an intermediate reforming process, such as a direct methanol fuel cell (DMFC). In this case, a methanol fuel and an aqueous methanol solution are stored separately in two containers and a wick is disposed between the two containers in a siphon fashion, with the container of the aqueous methanol solution communicating with the anode of the fuel cell. Methanol is siphoned from the methanol container to the aqueous methanol solution container in-situ when the methanol in the solution is consumed during the operation of the fuel cell. Through a proper design of the wick and the containers, the methanol concentration near the anode of the fuel cell is maintained within a preferable range. After the fuel in the fuel container is consumed, the fuel storage and delivery assembly can be easily removed from the fuel cell system.    DETAILED DESCRIPTION - A fuel storage and delivery device for transferring first liquid into second liquid of different substance(s) at small flow rate, comprises a first vessel containing the first liquid; a second vessel containing the second liquid; and a wick (100) wetted by the first liquid and positioned in a siphon fashion with the first portion contacting the first liquid and the second portion contacting the second liquid. The penetration rate of the first liquid in the wick is faster than that of the second liquid in the wick, thus a net amount of the first liquid is transferred into the second liquid.    An INDEPENDENT CLAIM is also included for a liquid-feed fuel cell system, comprising a membrane electrode assembly (MEA) (200) comprising an anode (130), a membrane electrolyte (140), and a cathode (150); and a fuel storage and delivery assembly comprising a fuel container (95) filled with a carbonaceous fuel, a fuel reservoir filled with an aqueous solution of the carbonaceous fuel and communicating with the MEA for supplying a fuel-bearing fluid to the MEA, and at least a wick wetted by the carbonaceous fuel and being positioned in a siphon fashion with the first portion contacting the carbonaceous fuel and the second portion contacting the aqueous solution of the carbonaceous fuel. The penetration rate of the carbonaceous fuel in the wick is faster than that of the aqueous solution of the carbonaceous fuel in the wick, thus the carbonaceous fuel is transferred into the aqueous solution of the carbonaceous fuel in-situ when the carbonaceous fuel in the fuel reservoir is consumed by the reactions at the MEA of the fuel cell system.    DESCRIPTION OF DRAWING(S) - The figure is a schematic sectional view in which fuel storage and delivery assembly is employed for a direct methanol fuel cell.    Sleeve tube (20)    Flow control pinch valve (60)    Fuel container (95)    Wick (100)    Anode (130)    Membrane electrolyte (140)    Cathode (150)    MEA (200)