Soil Microbial Fuel Cell Based Self-Powered Cathodic Biosensor for Sensitive Detection of Heavy Metals

Area of Science:

• Environmental Science
• Electrochemistry
• Biosensors

Background:

• Soil microbial fuel cells (SMFCs) are promising for soil-powered biosensing.
• Traditional anodic SMFCs face challenges in long-term, continuous monitoring of toxic pollutants due to instability.

Purpose of the Study:

• To develop a stable, self-powered biosensor for long-term heavy metal ion detection in soil.
• To investigate the performance of a carbon-felt-based cathodic SMFC biosensor.

Main Methods:

• A carbon-felt cathode was utilized in an SMFC configuration.
• The SMFC biosensor's performance was evaluated for heavy metal ion (Cd²⁺, Zn²⁺, Pb²⁺, Hg²⁺) detection.
• Long-term stability was assessed over four months of repeated detection cycles.

Main Results:

• The developed SMFC biosensor achieved an output voltage of approximately 400 mV with a 1000 Ω load.
• A sharp and rapid voltage increase was observed upon metal ion injection, stabilizing within 2-5 minutes.
• Quantification of Cd²⁺, Zn²⁺, Pb²⁺, and Hg²⁺ was possible in the range of 0.5–30 mg/L.
• The biosensor demonstrated efficient monitoring for four months with consistent output voltage under repeated metal ion detection.

Conclusions:

• The cathodic SMFC biosensor offers a stable and reliable platform for soil-powered, long-term heavy metal ion sensing.
• This technology presents a low-cost, self-powered solution for environmental monitoring applications.
• The findings highlight the potential for cathodic SMFCs in continuous pollutant detection.