NOVELTY - Deformational (M1) of an electrode (P1) for use in bio-fuel cell involves: forming at least one electrical connector on a substrate; forming at least one microchannel in a non-conductive casting mold comprising a material that will not passivate the electrode and can be reversibly sealed to the substrate; adhering the casting mold to the substrate; flowing an electron conductor solution through the microchannels; and curing the conduction solution to form (P1).    USE - In the production of electrode for biofuel cells (claimed) useful for generating electricity.    ADVANTAGE - The electrode prepared by the method allows use of biofuel cells in a variety of microscale applications. The electrode prepare by the method allows for the construction of complete biofuel cells on a single chip. The microfluidic fuel cells comprising the electrode exhibit increased transport efficiency that in turn increases current density as compared to previous bioanodes and biocathodes. The micromolded electrode prepared has a flow through structure that allows fuel to flow within the microelectrode thus increasing the current density of the biofuel cells. The electrode has current density greater than conventional biofuel electrodes thus increasing current density of the biofuel cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a biofuel cell (B1) for generating electricity using a fuel fluid comprising a substrate; a cathode supported by the substrate and capable of a reaction to reduce an oxidant in the presence of electrons to form water; an anode supported by the substrate and capable of a reaction to oxidize the fuel fluid, where at least one of the anode and cathode includes an enzyme for use in carrying out respective reaction. At least one of the cathode and anode is formed for flow of the fuel fluid within it for use in producing an electric current; or at least one of the anode and cathode has a width of about 200 microns and at least one surface having irregular, three dimensional topography capable of inducing convective flow of the fuel fluid and/or oxidant over the surface;    (2) an electrode (E1) for use in (B1) comprising either an electron conductor having a width less than 200 (preferably 1 - 200, more preferably 10 - 200, especially 10 - 50, particularly 10 - 20) microns and at least one surface having an irregular, three dimensional topography capable of inducing connective flow of the fuel fluid over the surface; or an electron conductor having surface area that is at least 1.5 (preferably 1.5 - 6) times greater than its geometric surface area, where one dimension of the electrode is less than 100 microns;    (3) a biocathode comprising: (E1); at least one enzyme capable of reacting with a reduced form of electron mediator and an oxidant to produce an oxidized form of the mediator and water; and an enzyme immobilization material containing electrocatalyst and optionally electron mediator, where the enzyme immobilization material is capable of immobilizing and stabilizing the enzyme. The material is permeable to the oxidant. An oxidized form of the electrocatalyst is capable of gaining electrons from the electron conductor to produce reduced form of electrocatalyst which capable of reacting with an oxidized form of electron mediator to produce a reduced form of the electron mediator and an oxidized form of the electrocatalyst; and    (4) a bioanode comprising (E1); at least one enzyme capable of reacting with an oxidized form of the electron mediator and the fuel fluid to produce an oxidized form of the fuel fluid and a reduced form of mediator, where the reduced form is capable of releasing electrons to the electron conductor; an enzyme immobilization material optionally containing the electron mediator and capable of immobilizing and stabilizing the enzyme, where the material is permeable to the fuel fluid and optionally the electron mediator; and optionally an electrocatalyst adjacent the electron conductor, where an oxidized form of the electrocatalyst is capable of reacting with the reduced form of the electron mediator to produce an oxidized form of the mediator and a reduced form of the electrocatalyst. The reduced form of the electrocatalyst is capable of releasing electrons to the electron conductor.