This article presents a study on the development of hybrid nanotube wires for high-power biofuel cells. The researchers engineered porous microwires composed of assembled and oriented carbon nanotubes (CNTs) to overcome the limitations of traditional carbon fibers in electrochemical systems. These CNT-based wires demonstrated significantly improved performance in oxygen reduction to water in saline buffer compared to conventional carbon fibers. Under physiological conditions, the maximum power density of a miniature membraneless glucose/oxygen CNT biofuel cell exceeded that of current state-of-the-art carbon fiber biofuel cells by far. The study highlights the challenges in engineering bioelectrochemical materials for sensors and miniature biofuel cells, particularly in physiological solutions where substrate concentrations and diffusion coefficients are low. The use of CNTs as electrode materials is promising due to their high specific surface area, which enhances current densities. However, the coating of macroelectrodes with CNTs does not always improve mass transport. Microelectrodes with diameters smaller than the diffusion length of their reactants allow for faster mass transport. The researchers developed a novel approach using biofunctionalized CNTs to create hybrid microwires that offer high current densities and low overpotential. These electrodes were optimized for oxygen reduction and biofuel cell applications, using glucose oxidase (GOx) as the anodic bioelectrocatalyst and bilirubin oxidase (BOD) as the cathodic one. The study demonstrated that the CNT-based biofuel cell achieved a power density of 740 μW cm⁻² at +0.57 V in physiological conditions, which is one to two orders of magnitude higher than previous glucose/oxygen biofuel cells. The study also showed that the CNT-based electrodes are more stable and efficient than conventional carbon fiber electrodes. The CNT-based biofuel cell exhibited a fourfold higher power density than the carbon fiber-based one and a significantly lower overpotential. The results indicate that the engineering of new porous and hybrid microfibres made of oriented and biofunctionalized CNTs is an ideal solution for achieving large surface area and fast mass transport. The study concludes that the adequate engineering of CNTs into microwires can open up new synthetic routes for novel electrodes that overcome mass transport limitations and provide high specific areas. The CNT-based biofuel cell demonstrated superior performance in terms of power density, current density, and stability compared to conventional carbon fiber-based biofuel cells.This article presents a study on the development of hybrid nanotube wires for high-power biofuel cells. The researchers engineered porous microwires composed of assembled and oriented carbon nanotubes (CNTs) to overcome the limitations of traditional carbon fibers in electrochemical systems. These CNT-based wires demonstrated significantly improved performance in oxygen reduction to water in saline buffer compared to conventional carbon fibers. Under physiological conditions, the maximum power density of a miniature membraneless glucose/oxygen CNT biofuel cell exceeded that of current state-of-the-art carbon fiber biofuel cells by far. The study highlights the challenges in engineering bioelectrochemical materials for sensors and miniature biofuel cells, particularly in physiological solutions where substrate concentrations and diffusion coefficients are low. The use of CNTs as electrode materials is promising due to their high specific surface area, which enhances current densities. However, the coating of macroelectrodes with CNTs does not always improve mass transport. Microelectrodes with diameters smaller than the diffusion length of their reactants allow for faster mass transport. The researchers developed a novel approach using biofunctionalized CNTs to create hybrid microwires that offer high current densities and low overpotential. These electrodes were optimized for oxygen reduction and biofuel cell applications, using glucose oxidase (GOx) as the anodic bioelectrocatalyst and bilirubin oxidase (BOD) as the cathodic one. The study demonstrated that the CNT-based biofuel cell achieved a power density of 740 μW cm⁻² at +0.57 V in physiological conditions, which is one to two orders of magnitude higher than previous glucose/oxygen biofuel cells. The study also showed that the CNT-based electrodes are more stable and efficient than conventional carbon fiber electrodes. The CNT-based biofuel cell exhibited a fourfold higher power density than the carbon fiber-based one and a significantly lower overpotential. The results indicate that the engineering of new porous and hybrid microfibres made of oriented and biofunctionalized CNTs is an ideal solution for achieving large surface area and fast mass transport. The study concludes that the adequate engineering of CNTs into microwires can open up new synthetic routes for novel electrodes that overcome mass transport limitations and provide high specific areas. The CNT-based biofuel cell demonstrated superior performance in terms of power density, current density, and stability compared to conventional carbon fiber-based biofuel cells.