NOVELTY - A fuel cell (100) comprises an anode (102) and a cathode (104) which is spaced apart from the anode. Anode and cathode enzymes are disposed on anode and cathode, respectively. The anode is configured and arranged for electroxidizing an anode reductant in the presence of the anode enzyme.    USE - Used in electrically-operated devices for implantation in human or animal (claimed). The fuel cell is configured for implantation into human or animal (human, mammal, bird or fish) to operate electrical devices such as a pacemaker, a nerve growth stimulator, a nerve stimulator for relief of chronic pain, a stimulator for regrowth of bone or other tissue, a drug-release valve, a microvalve and a fluid-flow control valve e.g. a valve in duct or urinary track.    ADVANTAGE - The electrochemical fuel cell comprising electrocatalyst is resistant to fouling, and thus is operated using compounds found in biological systems. The fuel cell used with biological system, provides electricity from plant, tree and plant residue. The fuel cell operates by passing biological fluids such as blood or sap. The fuel for operation of the fuel cell is provided by compounds in the blood, sap or other biological fluids or solids.    DETAILED DESCRIPTION - A fuel cell (100) comprises an anode (102) and a cathode (104) which is spaced apart from the anode. Anode and cathode enzymes are disposed on anode and cathode, respectively. The anode is configured and arranged for electroxidizing an anode reductant in the presence of the anode enzyme. The cathode is configured and arranged for electroreducing a cathode oxidant in the presence of the cathode enzymes. INDEPENDENT CLAIMS are also included for the following:    (a) generation of electric power which involves electroxidizing the anode reductant on the anode and electroreducing cathode oxidant on the cathode using respective enzymes;    (b) electrically-operated device which has electrically operated components coupled to anode and cathode of the fuel cell.    DESCRIPTION OF DRAWING(S) - The figure shows the cross-sectional view of the fuel cell.    Fuel cell (100)    Anode (102)    Spacers (103)    Cathode (104)    Anode electrolysis layer (106)    Anode electrolysis layer (108)    Non-fouling coating (109)