TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The channel comprises a first input adjacent to the first electrode and a second input adjacent to the second electrode. The first and second liquids are introduced through the respective inputs using corresponding pumps at similar flow rates. The channel further comprises a first outlet adjacent to the first electrode and a second outlet adjacent to the second electrode. The first and second inputs are configured such that the introduced liquids will be in physical contact along an interface in parallel laminar flow. A proton gradient is established along at least a portion of an interface between the first and second liquids. A diffusion of protons from the first electrode to the second electrode occurs primarily downstream of the second electrode. The channel has a straight flow channel geometry. A support has a surface with first and second recessed portions. The first and second electrodes occupy the first and second recessed portions, respectively, such that an upper surface of the first electrode and an upper surface of the second electrode are planar with the surface of the support. The first and second liquids are optionally miscible. The first electrode and the second electrode are spray-coated on a support. The first liquid comprises a fuel whose concentration is controlled by fuel sensor coupled to a fuel injector, flow rate monitor, fuel recycler, and/or gas exchanger. The second liquid comprises an oxidant. It is mechanically coupled to a gas exchanger, oxidant injector and/or oxidant reservoir. The first electrode comprises an anode. The second electrode comprises a cathode.    TECHNOLOGY FOCUS - POLYMERS - Preferred Materials: The support may comprise polycarbonate.    TECHNOLOGY FOCUS - CERAMICS AND GLASS - Preferred Materials: The support may comprise a glass slide.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Materials: The first liquid comprises methanol. The second liquid comprises oxygen or hydrogen peroxide.    TECHNOLOGY FOCUS - METALLURGY - Preferred Materials: The first and second electrodes comprise platinum. At least one of the electrodes comprises ruthenium.