Electricity generation from <italic>Geobacter sulfurreducens</italic> biofilm and its sensing application

Low-dimensional carbon materials, such as carbon nanotubes and graphene, can generate electrical signals through their interaction with dynamic water. This phenomenon provides a new direction for obtaining green electricity from the Earth’s water cycle. In 2014, it was discovered for the first time that moving droplets on the surface of graphene can generate “drawing potential”, which is expected to be developed as a new energy technology with negative carbon emissions. However, so far, the drawing potential is only realized on inorganic nanomaterials, mainly graphene. Biofilms are ubiquitous; however, whether they can generate drawing potential is not yet reported. In this study, a simple biofilm drawing generator was successfully assembled with Geobacter sulfurreducens biofilm as the core component. For the first time, the drawing potential on the surface of the biofilm was determined. This generator can achieve a maximum voltage of 0.43 V by moving droplets and up to 2.9 V by drawing a Chinese brush. In this study, a four-electrode sensor was constructed to realize self-driven calligraphy sensing by perceiving the motion direction of droplets. Compared with inorganic nanomaterials, biofilm is widely available in nature and can self-proliferate. Biofilm has the advantages of low production cost, zero pollution, and environmental friendliness. Moreover, biofilm is expected to be developed as a new bio-based hydrovoltaic technology. In the context of global carbon neutrality, this study proposes new directions for applying biomaterials in hydrovoltaic and self-driven sensing.