Enhanced stability of highly porous nanostructured gold anodes via polyaniline coating for abiotic glucose fuel cell

In recent years, advances in micro- and nano-electronics have enabled implantable and wearable ultra-low power bioelectronics to become a viable therapeutic option for the effective management of non-communicable diseases. Glucose fuel cells (GFCs) have significant potential as power sources for these devices, facilitating miniaturisation and, consequently, widening the application opportunities. For GFC technology to be deployable, the stability of the electrodes in physiological conditions is a major requirement. Accordingly, in this study, the use of a conductive polymeric coating was investigated to enhance the stability of nanostructured highly porous gold (hPG) films deposited onto gold electrodes on a printed circuit board to be used as the anode of an abiotic glucose fuel cell. Polyaniline (PANI) was electro-polymerised onto hPG, with the optimal polymerisation conditions identified as: 0.1 M monomer (aniline), 0.3 M dopant (HClO₄), and a three-minute deposition time. Subsequently, the optimised PANI/hPG/Au nanocomposite electrode was tested in a GFC. Although halving the electrochemical activity, in terms of power output, the PANI coating significantly stabilises the hPG electrode, with an overall activity loss, after 7 days of operation, of only 6 %, compared to a 97 % activity loss observed in the absence of PANI. The stabilisation effect of PANI is also maintained in the presence of Cl⁻¹ ions (concentration 10 mM), present in physiological fluids and known to negatively impact on the electroactivity of hPG towards glucose. Overall, this study demonstrates an effective route for electrode stabilisation in abiotic GFCs, paving the way for their practical application in bioelectronics.