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Keywords:

  • biosensors;
  • electrochemistry;
  • microbes;
  • microbial electrochemical activity;
  • microfluidics

Abstract

We report a laminar flow-based microfluidic bioelectrochemical system (BES) that was fabricated by using polydimethyl siloxane (PDMS) channels and gold electrodes. The microfluidic BES was operated as a potentiostatically controlled two-electrode system. A pure culture of Geobacter sulfurreducens strain PCA, which is a model electrode-respiring bacterium, was grown in the channel and respired with the electrode under strict anaerobic conditions. We took advantage of the short hydraulic retention time (≈2 min) and response times (<21 min) to rapidly test the effect of certain chemical stimuli, such as O2 and anthraquinone disulfide (AQDS), on electric current production by G. sulfurreducens. The results showed that: i) short-term (2 min) exposure to O2-saturated solution did not cause any irreversible toxicity to G. sulfurreducens, and ii) AQDS can be used as a redox mediator by G. sulfurreducens for shuttling electrons between the microbe and the electrode. We, therefore, demonstrate that the microfluidic BES is a promising research tool for gaining insight into microbial electrochemical activity. In our two-dimensional microfluidic-based research tool, a well-defined electrochemical environment can be maintained with the help of laminar flow without a membrane to separate two electrodes.