Biological fuel cells (BFCs) are a type of fuel cell in which enzymes, pure or inside whole cells, are used as catalysts. BFCs presents several advantages over abiotic fuel cells, such as low operational temperature and pressure and cost-effectiveness. On the other hand, key challenges of BFCs are mainly associated to low power densities and, in the case of pure enzymes, limited half-life.

Widely explored as a technology for wastewater treatment and simultaneous electricity generation, BFCs have enormous potential as self-powered sensors, which is currently gathering increasing attention.

This talk will provide an overview of our current research into miniature BFCs for sensing applications for either environmental monitoring or healthcare. To improve the sensing potential of BFCs we focus on: device design, electrode morphology and low-cost materials. Miniaturisation can lead to highly sensitive devices. The large electrode surface area to volume ratio in small-scale BFCs, in fact, increases the active surface area for reaction, thus leading to high fuel consumption efficiency, while the short electron spacing minimises the internal Ohmic losses. Micro-structured electrodes have demonstrated to lead to high current densities, and therefore greater baseline signal and detection limits of the sensor. Finally, with the aim of generating cost-effective devices, we explore the use of low cost materials, such as paper and biomass-derived oxygen reduction catalysts as a green and cheap alternative to platinum at the cathode.