Robust composite nanostructured anodes for the construction of innovative and highly performing glucose fuel cells

: (Alternative Format Thesis)

Abstract

Chronic diseases remain one of the leading causes of death and disability worldwide. Wearable and implantable bioelectronic devices offer valuable solutions for continuous health monitoring and disease management, yet their wider use is still limited by the dependence on bulky and short-lived batteries. Glucose fuel cells (GFCs), which directly convert glucose from body fluids into electrical energy, represent a promising approach to achieve compact, continuous, and biocompatible power generation. Among different systems, abiotic GFCs stand out due to their superior durability, tunable catalytic performance, and ease of fabrication.

This PhD project focused on developing an abiotic GFC capable of generating stable and reliable power to meet the needs of low-power bioelectronics. The research began with an overview of GFC technology, identifying abiotic catalysis as the most suitable strategy for long-term, implantable applications. The study then concentrated on the design and optimisation of the anode electrode, which is responsible for glucose oxidation and largely determines device performance and stability.

Initial work investigated highly porous gold (hPG) as a nanostructured electrode material, which provided a large surface area but suffered from instability in physiological environments. To overcome this limitation, a conductive polymer coating of polyaniline (PANI) was applied. The resulting PANI/hPG electrode showed outstanding mechanical and electrochemical stability, maintaining almost full activity after seven days compared with a 97% loss in uncoated electrodes. This stabilising effect persisted even in chloride-rich solutions mimicking physiological fluids, representing an important step towards practical application, although the electrochemical performance decreased by approximately 50% due to the lower conductivity of PANI compared with hPG.

Building on these results, a new one-step electrochemical method was developed to simultaneously form a nanocomposite of PANI and platinum nanoparticles (PtNPs) on hPG. This approach aimed to address the limited conductivity of PANI, as the incorporation of PtNPs significantly enhanced the electrode’s performance. The rapid and straightforward process produced an electrode combining high conductivity, stability, and catalytic activity. When tested in a GFC, the PANI-Pt/hPG/Au anode delivered a maximum power density of 61.7 ± 1.3 μW cm⁻² at 37 °C in phosphate buffer (pH 7.4) (PB) containing a physiological glucose concentration (6 mM) and sustained this performance for over three months, representing one of the most stable abiotic GFCs reported to date.

The electrocatalytic properties of the optimised PANI-Pt/hPG/Au electrode were then evaluated across clinically relevant glucose concentrations and compared with less complex structures. The nanocomposite electrode exhibited the highest sensitivity, 95.12 ± 2.54 µA mM⁻¹ cm⁻² in PB and 28.23 ± 2.39 µA mM⁻¹ cm⁻² in synthetic interstitial fluid (SIF) containing 6 mM glucose, while retaining more than 90% of its initial activity over prolonged operation in SIF. These results confirmed its strong potential for use in self-powered electrochemical glucose biosensors.

Finally, the developed electrode was integrated into a compact, coil-shaped GFC architecture designed for miniaturisation and implantable applications. The three-dimensional coil geometry maximised surface area while reducing its footprint, allowing for higher catalytic rates and improved power generation. The fuel cell delivered power densities of 149 ± 6.69 μW cm⁻² in PB and 56 ± 3.55 μW cm⁻² in SIF at 37 °C and 6 mM glucose. When connected to a power management system and a pulse generator circuit, the device successfully stimulated neuronal activity in an earthworm model, demonstrating its capability to provide stable and sufficient power for small-scale biomedical systems.

Overall, this research demonstrates a successful strategy for developing durable, efficient, and miniaturised abiotic GFCs. The results provide a solid foundation for advancing self-powered wearable and implantable bioelectronic devices, paving the way for practical applications in personalised and long-term healthcare.

Date of Award	24 Jun 2026
Original language	English
Awarding Institution	University of Bath
Sponsors	University Research Studentship Award (URSA)
Supervisor	Mirella Di Lorenzo (Supervisor), Benjamin Metcalfe (Supervisor) & Hannah Leese (Supervisor)