Enzymatic biofuel cells have emerged as an interesting candidate as power source for implantable biomedical applications (Figure 1-a). A key step for the function of such cells is the electron transfer, from the active site of the enzyme to the electrode surface, which in our case is aided by a mediator for shuttling the electrons. The mediator gel we use is a copolymer consisting of N,N-dimethyl acrylamide (DMAA) with hydrophilic backbone, methacryloyloxy benzophenone (MABP) as crosslinking agent and a ferrocene based electron transfer agent. This gel immobilizes the enzyme within the redox polymer network by a mixture of covalent links and entrapment within the hydrogel. The redox hydrogel swells in water and is capable of charge transport. One of the main challenges for enzymatic biofuel cell systems is to increase the output power. Integration of multi-walled carbon nanotubes (MWCNT) into the mediator gel enhances the conductivity of the gel, increases the surface area of the electrode and fastens the electron transfer rate of the redox reaction. This results in 12 times faster diffusion of charges to the electrode surface and thus a higher output current. The presence of CNTs also improves the stability of the enzyme and allows for higher loading of the enzyme in the film, again leading to an enhanced output current up to a factor of 20 compared to a non-modified mediator gel (Figure 1-b).

CNT loaded mediator gels for enzymatic biofuel cells

248th National Meeting (2014)

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