A glucose/oxygen enzymatic fuel cell exceeding 1.5 V based on glucose dehydrogenase immobilized onto polyMethylene blue-carbon nanotubes modified double-sided screen printed electrodes: Proof-of-concept in human serum and saliva

Herein we report on a new hybrid enzymatic fuel cell (EFC) based on mediated/direct electron transfer, which is assembled by considering two different configurations: i) two normal screen printed electrodes (SPEs) in one electrochemical cell and ii) two double-sided SPEs each one comprising both bioanode and biocathode, connected in series. After a deep electrodes characterization, they are assembled according to the first configuration obtaining a maximal power output of 25.8 ± 0.7 μW cm−2 at a cell voltage of 0.57 V and an open circuit voltage (OCV) of 0.78 V. Moreover, the EFC performance are substantially improved by using the second configuration (EFCs connected in series) obtaining a maximal power output of 59.6 ± 1.9 μW cm−2 at a cell voltage of 1.16 V and an open circuit voltage (OCV) of 1.58 V. Finally, the last EFC configuration is tested in human saliva and serum showing good performance in terms of OCV and maximal power output as proof-of-concept to power implantable bioelectronics (e.g., pacemaker) or develop self-powered glucose biosensors.