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The application of microbial fuel cell (MFC)-based sensors has attracted considerable interest in the last decade because of their advantages in terms of low cost, self-sustainability without power sources, and environmentally friendly nature. Detecting and monitoring toxicities, especially heavy metals, in wastewater is critical to ensuring a safe environment for human health. This study introduces a low-cost, membrane-less, compact, and easy-to-use soil MFC (SMFC)-based sensor to detect copper (Cu2+) and ferricyanide ([Fe(CN)6]3−) ions. A series of five concentrations of toxic ions from 100 mg/L to 500 mg/L were used to evaluate the sensing capability of the proposed SMFC. An immediate increase in voltage was observed when SMFC was exposed to the toxic agents, with the maximum peak reached in about 30–60 min (depending on the concentrations). The highest IR% (inhibition ratio) was 100.8% for 500 mg/L of Cu2+. The IR% of ferricyanide was lower, reaching a maximum of 49.2%. A linear relationship between IR% and toxic agent concentration was observed for both Cu2+ and ferricyanide detection in both rounds of exposure. The employment of the designed SMFC enabled the detection of Cu2+ and ferricyanide in a simple method. [ABSTRACT FROM AUTHOR]

Soil microbial fuel cells (SMFCs) are attractive for low-cost bioelectricity generation. In this study, a multiwalled carbon nanotube paper (MCNTP) was fabricated by a simple method for use as the anode and cathode electrodes in a stab-type membrane-less SMFC (SSMFC). Activated carbon powder, carbon fibers, and cellulose fibers were bound by multiwalled carbon nanotube paint to form the MCNTP. As a result, the MCNTP exhibited high conductivity, flexibility, and durability. In addition, the SSMFC was designed as a module mounted with three anodes in series and a floating air cathode. The SSMFC could be activated on demand by simply stabbing in the wet soil. Experimental results showed that the floating cathode outperformed the non-floating one. The SSMFC generated the output shortly after being plugged into the wet soil. The maximum power density was at the level of 60–70 mW/m2 for three separate experiment cycles. Additionally, a single SSMFC was used to power a clock as an example to demonstrate its practical use. [ABSTRACT FROM AUTHOR]

Soil microbial fuel cells (SMFCs) are a promising cost-effective power source for on-demand electricity generation applications. So far, reported SMFC configurations are usually bulky and hard to setup. In this study, a low-cost portable plugged-type SMFC (PSMFC) was designed and fabricated for on-demand micropower generation. The PSMFC can be activated just by plugging into natural wet soil, which is easy to access in the natural condition. The PSMFC uses carbon-based electrodes for cost-effectiveness. After setting the PSMFC into the soil to activate, it started to produce electricity after 1 h and reached the power density of 7.3 mW/m2 after 48 h. The proposed PSMFC can potentially generate electricity for remote sensors or soil sensing systems. [ABSTRACT FROM AUTHOR]