A paper-based microbial fuel cell array for rapid and high-throughput screening of electricity-producing bacteria

Abstract

There is a large global effort to improve microbial fuel cell (MFC) techniques and advance their translational potential toward practical, real-world applications. Significant boosts in MFC performance can be achieved with the development of new techniques in synthetic biology that can regulate microbial metabolic pathways or control their gene expression. For these new directions, a high-throughput and rapid screening tool for microbial biopower production is needed. In this work, a 48-well, paper-based sensing platform was developed for the high-throughput and rapid characterization of the electricity-producing capability of microbes. 48 spatially distinct wells of a sensor array were prepared by patterning 48 hydrophilic reservoirs on paper with hydrophobic wax boundaries. This paper-based platform exploited the ability of paper to quickly wick fluid and promoted bacterial attachment to the anode pads, resulting in instant current generation upon loading of the bacterial inoculum. We validated the utility of our MFC array by studying how strategic genetic modifications impacted the electrochemical activity of various Pseudomonas aeruginosa mutant strains. Within just 20 minutes, we successfully determined the electricity generation capacity of eight isogenic mutants of P. aeruginosa. These efforts demonstrate that our MFC array displays highly comparable performance characteristics and identifies genes in P. aeruginosa that can trigger a higher power density.

Rapid Characterization of Bacterial Electrogenicity Using a Single-Sheet Paper-Based Electrofluidic Array

“…The OCVs of the 8-well MFCs generates 1.7% variation with LB medium, which is far less than that of other MFC arrays (25%) and even our previous MFC arrays (2.5%) (Choi et al, 2015). This low percent deviation is mainly because of (i) consistent cathodic reactions from device to device by accessing freely available oxygen in the air and (ii) simplified device configuration, fabrication, and operation by integrating all components in a single sheet of paper.…”

“…This hypothesis is based on our extensive experience in biosensors and our recent series of breakthroughs in microfabricating bioelectrochemical systems, all of which suggest that using paper as a device substrate inherently produces favorable conditions for ease, control, rapidity, sensitivity, and parallel analysis of bacterial electrogenicity. Recently, we found that using a paper-based anode/cathode chamber, or reservoir, instead of the usual rigid materials allows for rapid adsorption of bacteria-containing liquid (Fraiwan et al, 2013, 2016; Fraiwan and Choi, 2014, 2016; Choi and Choi, 2015; Choi et al, 2015; Lee and Choi, 2015). This adsorption immediately promotes bacterial cell attachment to the electrode (e.g., biofilm formation), where bacterial respiration can then transfer electrons from the organic substrates to the electrode directly (mediatorless) or indirectly (mediator).…”

“…MFCs using paper, therefore, require only very short start-up times relative to conventional MFCs as paper substrates substantially reduce the time traditional MFCs require to accumulate and acclimate bacteria on the anode. By exploiting paper as a unique biofilm substratum for bacteria, we introduce a paper-based microbial sensor array as a high-throughput, rapid characterization tool for bacterial electrogenic studies (Fraiwan and Choi, 2014; Choi et al, 2015). For the first time, a 48-well MFC array was fabricated on paper substrates, providing 48 high-throughput measurements and highly comparable performance characteristics in a reliable and reproducible manner (Choi et al, 2015).…”

“…By exploiting paper as a unique biofilm substratum for bacteria, we introduce a paper-based microbial sensor array as a high-throughput, rapid characterization tool for bacterial electrogenic studies (Fraiwan and Choi, 2014; Choi et al, 2015). For the first time, a 48-well MFC array was fabricated on paper substrates, providing 48 high-throughput measurements and highly comparable performance characteristics in a reliable and reproducible manner (Choi et al, 2015). Within an hour, we successfully determined the electricity generation capacity of two known bacterial exoelectrogens and another metabolically more voracious organism with eight isogenic mutants.…”

Effect of temperature on a miniaturized microbial fuel cell (MFC)

“…During the past two decades, significant improvement on MFC has been demonstrated; for instance, the power density of microbial fuel cells have improved by more than four orders of magnitude, from 0.1 mWm −2 to 7.72 Wm −2 [4][5][6]. In order to improve the power density, a number of research have been performed, such as implementing the anode with high surface area to volume ratio [5,[7][8][9], investigating the performance of different species of exoelectrogen [10,11], investigating different MFC configurations, and investigating different operation conditions, including temperature, pH, flow rate, etc. [12][13][14][15].…”