Bacteria in nature predominantly grow as biofilms on living and non-living surfaces. The development of biofilms on non-living surfaces is significantly affected by the surface micro/nano topography. The main goal of this dissertation is to study the interaction between microorganisms and nanopatterned surfaces. In order to engineer the surface with well-defined and repeatable nanoscale structures, a new, versatile and scalable nanofabrication method, termed Spun-Wrapped Aligned Nanofiber lithography (SWAN lithography) was developed. This technique enables high throughput fabrication of micro/nano-scale structures on planar and highly non-planar 3D objects with lateral feature size ranging from sub-50 nm to a few microns, which is difficult to achieve by any other method at present. This nanolithography technique was then utilized to fabricate nanostructured electrode surfaces to investigate the role of surface nanostructure size (i.e. 115 nm and 300 nm high) in current production of microbial fuel cells (MFCs). Through comparing the S. oneidensis attachment density and current density (normalized by surface area), we demonstrated the effect of the surface feature size which is independent of the effect on the surface area. In order to better understand the mechanism of microorganism adhesion on nanostructured surfaces, we developed a biophysical model that calculates the total energy of adhered cells as a function of nanostructure size and spacing. Using this model, we predict the attachment density trend for Candida albicans on nanofiber-textured surfaces. The model can be applied at the population level to design surface nanostructures that reduce cell attachment on medical catheters. The biophysical model was also utilized to study the motion of a single Candida albicans yeast cell and to identify the optimal attachment location on nanofiber coated surfaces, thus leading to a better understanding of the cell-substrate interaction upon attachment. / Ph. D. / Formation of surface associated multicellular communities of microorganisms known as biofilms is of concern in medical settings as well as in industries such as oil refineries and marine engineering. It has been shown that micro/nanoscale surface features can highly regulate the process of biofilm formation and the attached cell activities. In this dissertation, we study the interaction between surface nanoscale structures and bacterial adhesion by experiments and biophysical modelling. We develop the Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and high throughput technique for masterless nanopatterning of hard materials. Using this technique, we demonstrate high fidelity whole surface single step nanopatterning of bulk and thin film surfaces of regularly and irregularly shaped 3D objects. SWAN lithography is used to texturize the electrode surface of microbial fuel cells (MFCs), which are envisioned as an alternative sustainable energy source. Compared to the non-patterned electrodes, the electrodes with 115 nm surface patterns facilitate larger biofilm coverage and 40% higher current production. We also develop a biophysical model to optimally texturize the surface of central venous and uretic medical catheters to prevent biofilm formation by fungal pathogen, Candida albicans. We show that the surface structures that result the highest cell total energy retained the least C. albicans. Furthermore, the adhesion behaviour of a single yeast cell is also experimentally studied in conjunction with the developed model.

O nitrato nas águas subterrâneas é considerado um dos principais problemas com relação aos padrões de potabilidade estabelecidos pela Portaria MS nº 2914/2011, o limite é de 10 mg NNO3-/L, tendo em vista que a ingestão de altas concentrações de nitrato está associada a doenças como câncer e a metahemoglobinemia. As preocupações com o nitrato devem-se as concentrações insidiosas e persistentes deste íon registradas pela CETESB desde o início do monitoramento das águas subterrâneas em 1990. O presente trabalho propôs a avaliação de um processo alternativo para remoção de nitrato, trata-se de um sistema bioeletroquímico, também conhecido como MFC (Microbial Fuel Cells), que utiliza microrganismos para desnitrificação. Esse tratamento consiste no uso de processos biológicos potencializados pelo processo de eletrólise, aproveitando desta forma, os principais pontos característicos de cada processo de maneira combinada. O sistema foi testado em escala de bancada, e consiste basicamente em uma câmara anódica onde ocorre a oxidação da matéria orgânica e uma câmara catódica onde ocorre o processo de redução do nitrato a N2. Entre as câmaras é utilizada uma membrana de troca iônica de forma a permitir somente a passagem de prótons da câmara anódica para a catódica, além de impedir a difusão de oxigênio para a câmara catódica. O experimento realizou 8 testes variando a taxa de aplicação total de 2,88 a 11,52 L/dia com uma concentração 15 mg N-NO3-/L. Nos últimos dois testes ainda foi aplicada uma tensão externa. O sistema atingiu uma eficiência média de remoção de nitrato de 80,84 ± 16,73 %. As concentrações finais de nitrato permaneceram dentro dos padrões de potabilidade, com valor médio de 1,88 ± 2,03 mg N-NO3-/L, obtendo-se uma taxa de desnitrificação de 0,0498 ± 0,03 kg/m³.dia. O acúmulo de nitrito no sistema teve valor médio de 0,36 ± 0,37 mg N-NO2-/L. / Nitrate in groundwater is considered to be one of the main problems with regard to the potability standards established by Ordinance MS nº 2914/2011, the limit is 10 mg N-NO3-/L, considering that the intake of high concentrations of nitrate Is associated with diseases such as cancer and methemoglobinemia. Concerns with nitrate are due to the insidious and persistent concentrations of this ion recorded by CETESB since the beginning of groundwater monitoring in 1990. The present work proposed the evaluation of an alternative process for nitrate removal. This is a bioelectrochemical system, also known as MFC (Microbial Fuel Cells), which uses microorganisms for denitrification. This treatment consists in the use of biological processes potentiated by the electrolysis process, thus taking advantage of the main characteristic points of each process in a combined manner. The system was tested on a bench scale, and basically consists of an anodic chamber where the oxidation of organic matter occurs and a cathodic chamber where the process of nitrate reduction to N2 occurs. Between the chambers an ion exchange membrane is used in order to allow only the passage of protons from the anode chamber to the cathodic, in addition to preventing the diffusion of oxygen to the cathodic chamber. The experiment performed 8 tests varying the total application rate from 2.88 to 11.52 L/d with a concentration of 15 mg N-NO3-/L. In the last two tests an external voltage was still applied. The system achieved an average nitrate removal efficiency of 80.84 ± 16.73%. The final concentrations of nitrate remained within the potability standards, with an average value of 1.88 ± 2.03 mg N-NO3-/L, obtaining a denitrification rate of 0.0498 ± 0.03 kg/m³.d. The accumulation of nitrite in the system had an average value of 0.36 ± 0.37 mg N-NO2-/L.

O nitrato nas águas subterrâneas é considerado um dos principais problemas com relação aos padrões de potabilidade estabelecidos pela Portaria MS nº 2914/2011, o limite é de 10 mg NNO3-/L, tendo em vista que a ingestão de altas concentrações de nitrato está associada a doenças como câncer e a metahemoglobinemia. As preocupações com o nitrato devem-se as concentrações insidiosas e persistentes deste íon registradas pela CETESB desde o início do monitoramento das águas subterrâneas em 1990. O presente trabalho propôs a avaliação de um processo alternativo para remoção de nitrato, trata-se de um sistema bioeletroquímico, também conhecido como MFC (Microbial Fuel Cells), que utiliza microrganismos para desnitrificação. Esse tratamento consiste no uso de processos biológicos potencializados pelo processo de eletrólise, aproveitando desta forma, os principais pontos característicos de cada processo de maneira combinada. O sistema foi testado em escala de bancada, e consiste basicamente em uma câmara anódica onde ocorre a oxidação da matéria orgânica e uma câmara catódica onde ocorre o processo de redução do nitrato a N2. Entre as câmaras é utilizada uma membrana de troca iônica de forma a permitir somente a passagem de prótons da câmara anódica para a catódica, além de impedir a difusão de oxigênio para a câmara catódica. O experimento realizou 8 testes variando a taxa de aplicação total de 2,88 a 11,52 L/dia com uma concentração 15 mg N-NO3-/L. Nos últimos dois testes ainda foi aplicada uma tensão externa. O sistema atingiu uma eficiência média de remoção de nitrato de 80,84 ± 16,73 %. As concentrações finais de nitrato permaneceram dentro dos padrões de potabilidade, com valor médio de 1,88 ± 2,03 mg N-NO3-/L, obtendo-se uma taxa de desnitrificação de 0,0498 ± 0,03 kg/m³.dia. O acúmulo de nitrito no sistema teve valor médio de 0,36 ± 0,37 mg N-NO2-/L. / Nitrate in groundwater is considered to be one of the main problems with regard to the potability standards established by Ordinance MS nº 2914/2011, the limit is 10 mg N-NO3-/L, considering that the intake of high concentrations of nitrate Is associated with diseases such as cancer and methemoglobinemia. Concerns with nitrate are due to the insidious and persistent concentrations of this ion recorded by CETESB since the beginning of groundwater monitoring in 1990. The present work proposed the evaluation of an alternative process for nitrate removal. This is a bioelectrochemical system, also known as MFC (Microbial Fuel Cells), which uses microorganisms for denitrification. This treatment consists in the use of biological processes potentiated by the electrolysis process, thus taking advantage of the main characteristic points of each process in a combined manner. The system was tested on a bench scale, and basically consists of an anodic chamber where the oxidation of organic matter occurs and a cathodic chamber where the process of nitrate reduction to N2 occurs. Between the chambers an ion exchange membrane is used in order to allow only the passage of protons from the anode chamber to the cathodic, in addition to preventing the diffusion of oxygen to the cathodic chamber. The experiment performed 8 tests varying the total application rate from 2.88 to 11.52 L/d with a concentration of 15 mg N-NO3-/L. In the last two tests an external voltage was still applied. The system achieved an average nitrate removal efficiency of 80.84 ± 16.73%. The final concentrations of nitrate remained within the potability standards, with an average value of 1.88 ± 2.03 mg N-NO3-/L, obtaining a denitrification rate of 0.0498 ± 0.03 kg/m³.d. The accumulation of nitrite in the system had an average value of 0.36 ± 0.37 mg N-NO2-/L.

Microbial fuel cells (MFC) are an emerging renewable technology which converts complex organic matter to electrical power using microorganisms as the biocatalyst. A variety of biological relevant organic matters such as glucose, acetate and ethanol have been utilized for the successful operation of a MFC. In this regard, the investigation of a MFC inoculated with ethanol oxidizing bacteria is of particular interest for this research due to its ability to simultaneously produce electricity while reducing ethanol pollution (a type of volatile organic carbon (VOC) pollutant) with potential use in modified biological air pollution control technology such as biofiltration. In this research, ethanol-oxidizing microbial species isolated from soil and compost samples were identified, with Acinetobacter calcoaceticus being the dominant strain. In order to understand the metabolism of the anode microbial cells, which is considered to be the key dictating the performance of a MFC, a systematic analysis/optimization of the growth rate and biomass production for A. calcoaceticus were carried out. A maximum specific growth rate with a final biomass concentration of 1.68 g/l was derived when aerated at a rate of 0.68 vvm. It has been recognized that one of the principle constraints in increasing the current density of MFCs is the electron transfer from the bacteria to the anode. In this sense, the addition of a redox mediator, which facilitates the process of the electron transfer, is desired for the efficient operation of a MFC. Thionine, methylene blue (MB), resorufin and potassium ferricyanide that have been profusely utilized as effective mediator compounds in many MFC studies, however, specific information on the biomass sorption of these compounds was lacking and therefore were selected for this research. All mediators tested were reduced biologically in A. calcoaceticus inoculated samples as indicated by the color transition from the pigmented oxidized form to the colorless reduced form. Subsequent tests on mediator color removal revealed that physical adsorption by the biomass, aggregation as well as precipitation accounted for a significant portion of the color loss for thionine and MB. It was speculated that the fraction of the initial mediator concentration sequestered, aggregated and/or precipitated no longer contributed to the electron transfer process, resulting in a current production which was proportional to the measurable mediator concentration remained in anode solution. To verify this hypothesis, chronoamperometric measurements were conducted for various mediator systems at known initial and measurable concentrations. The data obtained on the current produced were in good agreement with the theoretical predictions calculated from the actual mediator concentration, suggesting that the current produced depended on the concentration of mediator remaining in solution. Finally, the microbial reduction kinetics and the cytotoxicity of potassium ferricyanide were analyzed. The reduction of potassium ferricyanide followed zero order kinetics with the specific reduction rate increased as the initial mediator concentration increased from 1 mM to 200 mM. Inhibitory effects on cell growth were observed at initial potassium ferricyanide concentration of 50 mM.

The modification of anode materials is important to enhance the power generation of MFCs (microbial fuel cells). A novel and cost-effective modified anode that is fabricated by dispersing manganese dioxide (MnO2) and HNTs (Halloysite nanotubes) on carbon cloth to improve the MFCs' power production was reported. The results show that the MnO2/HNT anodes acquire more bacteria and provide greater kinetic activity and power density compared to the unmodified anode. Among all modified anodes, 75 wt% MnO2/HNT exhibits the highest electrochemical performance. The maximum power density is 767.3 mWm(-2), which 21.6 higher than the unmodified anode (631 mW/m(2)). Besides, CE (Coulombic efficiency) was improved 20.7, indicating that more chemical energy transformed to electricity. XRD (X-Ray powder diffraction) and FTIR (Fourier transform infrared spectroscopy) are used to characterize the structure and functional groups of the anode. CV (cyclic voltammetry) scans and SEM (scanning electron microscope) images demonstrate that the measured power density is associated with the attachment of bacteria, the microorganism morphology differed between the modified and the original anode. These findings demonstrate that MnO2/FINT nanocomposites can alter the characteristics of carbon cloth anodes to effectively modify the anode for practical MFC applications. (C) 2016 Elsevier Ltd. All rights reserved.

Microbial electrochemical systems (MESs) have attracted much research attention in recent years due to their promising applications in renewable energy generation, bioremediation, and wastewater treatment. In a MES, microorganisms interact with electrodes via electrons, catalyzing oxidation and reduction reactions at the anode and the cathode. The bacterial community of a high power mixed consortium MESs (maximum power density is 6.5W/m��) was analyzed by using denature gradient gel electrophoresis (DGGE) and 16S DNA clone library methods. The bacterial DGGE profiles were relatively complex (more than 10 bands) but only three brightly dominant bands in DGGE results. These results indicated there are three dominant bacterial species in mixed consortium MFCs. The 16S DNA clone library method results revealed that the predominant bacterial species in mixed culture is Geobacter sp (66%), Arcobacter sp and Citrobacter sp. These three bacterial species reached to 88% of total bacterial species. This result is consistent with the DGGE result which showed that three bright bands represented three dominant bacterial species. Exoelectrogenic bacterial strain SX-1 was isolated from a mediator-less microbial fuel cell by conventional plating techniques with ferric citrate as electron acceptor under anaerobic conditions. Phylogenetic analysis of the 16S rDNA sequence revealed that it was related to the members of Citrobacter genus with Citrobacter sp. sdy-48 being the most closely related species. The bacterial strain SX-1 produced electricity from citrate, acetate, glucose, sucrose, glycerol, and lactose in MFCs with the highest current density of 205 mA/m�� generated from citrate. Cyclic voltammetry analysis indicated that membrane associated proteins may play an important role in facilitating electron transfer from the bacteria to the electrode. This is the first study that demonstrates that Citrobacter species can transfer electrons to extracellular electron acceptors. Citrobacter strain SX-1 is capable of generating electricity from a wide range of substrates in MFCs. This finding increases the known diversity of power generating exoelectrogens and provids a new strain to explore the mechanisms of extracellular electron transfer from bacteria to electrode. The wide range of substrate utilization by SX-1 increases the application potential of MFCs in renewable energy generation and waste treatment. Anode properties are critical for the performance of microbial electrolysis cells (MECs). Inexpensive Fe nanoparticle modified graphite disks were used as anodes to preliminarily investigate the effects of nanoparticles on the performance of Shewanella oneidensis MR-1 in MECs. Results demonstrated that average current densities produced with Fe nanoparticle decorated anodes were up to 5.9-fold higher than plain graphite anodes. Whole genome microarray analysis of the gene expression showed that genes encoding biofilm formation were significantly up-regulated as a response to nanoparticle decorated anodes. Increased expression of genes related to nanowires, flavins and c-type cytochromes indicate that enhanced mechanisms of electron transfer to the anode may also have contributed to the observed increases in current density. The majority of the remaining differentially expressed genes were associated with electron transport and anaerobic metabolism demonstrating a systemic response to increased power loads. The carbon nanotube (CNT) is another form of nano materials. Carbon nanotube (CNT) modified graphite disks were used as anodes to investigate the effects of nanostructures on the performance S. oneidensis MR-1 in microbial electrolysis cells (MECs). The current densities produced with CNT decorated anodes were up to 5.6-fold higher than plain graphite anodes. Global transcriptome analysis showed that cytochrome c genes associated with extracellular electron transfer are up-expressed by CNT decorated anodes, which is the leading factor to contribute current increase in CNT decorated anode MECs. The up regulated genes encoded to flavin also contribute to current enhancement in CNT decorated anode MECs. / Graduation date: 2013

Microbial fuel cells were designed and operated using waste activated sludge as a substrate and as a source of microorganisms for the anodic chamber. Waste activated sludge provided a bacterial consortium predisposed to the solubilization of particulate matter and utilization of substrates commonly found in wastewater. Dissolved oxygen and ferricyanide were used as the electron acceptors in the catholytes. Microbial fuel cell comparisons were made while operating under identical conditions but using the two different electron acceptors. Comparisons were based on the electricity production observed during MFC operation, wastewater quality of the waste activated sludge anolytes and the community level physiological profiling of the microbial communities in the anolytes. Electrons liberated during substrate utilization in the anodic chamber traveled to the cathodic chamber where they reduced the electron acceptors. The anode and cathode chambers were connected by a Nafion ® proton exchange membrane to allow for cation migration. Various soluble carbon sources were dosed to the microbial fuel cells at measured intervals during operation via direct injection to the anolyte. During bovine serum albumin dosing, average power production levels reached 0.062 mW and 0.122 mW for the dissolved oxygen microbial fuel cell and the ferricyanide microbial fuel cell, respectively. These were 100% and 25% greater than the power production levels observed throughout the rest of the study. Increases in current production were observed following the dosing of sodium acetate, glucose and bovine serum albumin. No increase in current was observed following glycerol dosing. Sodium acetate dosing triggered an immediate response, while glucose and bovine serum albumin responded in approximately 2 minutes. A chemical oxygen demand mass balance was calculated for both microbial fuel cells. The lack of balance closure was attributed to unmeasured methane production. An accumulation of particulate waste activated sludge components was observed for both microbial fuel cells. The anolyte pH during operation was typically less than waste activated sludge pH, which was attributed to volatile fatty acid accumulation in the anolytes during fermentation processes. Community level physiological profiling was accomplished through the analysis of ecological data obtained with BIOLOG ® ECOplates. Samples were plated and analyzed under anaerobic conditions, mimicking the environment in the anode chamber of the MFCs. ECOplate data were transformed by a logarithmic function prior to principle component analysis. The community level physiological profiling indicated that shifts in the microbial community profile, as measured through the carbon source utilization patterns, occurred throughout acclimation and following the dosing of various carbon source substrates. Shifts due to glycerol dosing differed from shifts due to the dosing of sodium acetate, glucose and bovine serum albumin.

Microbial fuel cells were designed and operated using waste activated sludge as a substrate and as a source of microorganisms for the anodic chamber. Waste activated sludge provided a bacterial consortium predisposed to the solubilization of particulate matter and utilization of substrates commonly found in wastewater. Dissolved oxygen and ferricyanide were used as the electron acceptors in the catholytes. Microbial fuel cell comparisons were made while operating under identical conditions but using the two different electron acceptors. Comparisons were based on the electricity production observed during MFC operation, wastewater quality of the waste activated sludge anolytes and the community level physiological profiling of the microbial communities in the anolytes. Electrons liberated during substrate utilization in the anodic chamber traveled to the cathodic chamber where they reduced the electron acceptors. The anode and cathode chambers were connected by a Nafion ® proton exchange membrane to allow for cation migration. Various soluble carbon sources were dosed to the microbial fuel cells at measured intervals during operation via direct injection to the anolyte. During bovine serum albumin dosing, average power production levels reached 0.062 mW and 0.122 mW for the dissolved oxygen microbial fuel cell and the ferricyanide microbial fuel cell, respectively. These were 100% and 25% greater than the power production levels observed throughout the rest of the study. Increases in current production were observed following the dosing of sodium acetate, glucose and bovine serum albumin. No increase in current was observed following glycerol dosing. Sodium acetate dosing triggered an immediate response, while glucose and bovine serum albumin responded in approximately 2 minutes. A chemical oxygen demand mass balance was calculated for both microbial fuel cells. The lack of balance closure was attributed to unmeasured methane production. An accumulation of particulate waste activated sludge components was observed for both microbial fuel cells. The anolyte pH during operation was typically less than waste activated sludge pH, which was attributed to volatile fatty acid accumulation in the anolytes during fermentation processes. Community level physiological profiling was accomplished through the analysis of ecological data obtained with BIOLOG ® ECOplates. Samples were plated and analyzed under anaerobic conditions, mimicking the environment in the anode chamber of the MFCs. ECOplate data were transformed by a logarithmic function prior to principle component analysis. The community level physiological profiling indicated that shifts in the microbial community profile, as measured through the carbon source utilization patterns, occurred throughout acclimation and following the dosing of various carbon source substrates. Shifts due to glycerol dosing differed from shifts due to the dosing of sodium acetate, glucose and bovine serum albumin.

Today’s information-centered world leads the ever-increasing consumer demand for more powerful, multifunctional portable devices. Additionally, recent developments on long-lasting energy sources and compliant, flexible systems, have introduced new required features to the portable devices industry. For example, wireless sensor networks are in urgent need of self-sustainable, easy-to-deploy, mobile platforms, wirelessly interconnected and accessible through a cloud computing system. The objective of my doctoral work is to develop integration strategies to effectively fabricate mechanically flexible, energy-independent systems, which could empower sensor networks for a great variety of new exciting applications. The first module, flexible electronics, can be achieved through several techniques and materials. Our main focus is to bring mechanical flexibility to the state-of-the-art high performing silicon-based electronics, with billions of ultra-low power, nano-sized transistors. Therefore, we have developed a low-cost batch fabrication process to transform standard, rigid, mono-crystalline silicon (100) wafer with devices, into a thin (5-20 m), mechanically flexible, optically semi-transparent silicon fabric. Recycling of the remaining wafer is possible, enabling generation of multiple fabrics to ensure lowcost and optimal utilization of the whole substrate. We have shown mono, amorphous and poly-crystalline silicon and silicon dioxide fabrics, featuring industry’s most advanced high-/metal-gate based capacitors and transistors. The second module consists on the development of efficient energy scavenging systems. First, we have identified an innovative and relatively young technology, which can address at the same time two of the main concerns of human kind: water and energy. Microbial fuel cells (MFC) are capable of producing energy out the metabolism of bacteria while treating wastewater. We have developed two micro-liter MFC designs, one with carbon nanotubes (CNT)-based anode and the second with a more sustainable design and easy to implement. Power production ranges from 392 to 100 mW/m3 depending on design. Additionally we have explored a flexible thermoelectric generator (0.139 μW/cm2) and a lithium-ion battery (~800 μAh/m2) for back-up energy generation and storage. Future work includes the implementation of a self-powered System-on-Package which gathers together energy generation, storage and consumption. Additionally we are working to demonstrate Complementary Metal-Oxide-Semiconductor (CMOS) circuitry on our flexible platform, as well as memory systems.

Microbial fuel cells (MFCs) are novel green technologies that convert chemical energy stored in biomass into electricity through microbial metabolisms. Both fossil fuel depletion and environmental concern have fostered significant interest in MFCs for both wastewater treatment and electricity generation. However, MFCs have not yet been used for practical applications due to their low power outputs and challenges associated with scale-up. High throughput screening devices for parallel studies are highly necessary to significantly improve and optimize MFC working conditions for future practical applications. Here in this research, microfabricated platforms of microbial fuel cell array as high throughput screening devices for MFC parallel studies have been developed. Their utilities were described with environmental sample screening to uncover electricigens with higher electrochemical activities. The first version of the MFC arrays is a batch-mode miniaturized 24-well MFC array using ferricyanide as catholyte. Several environmental species that showed higher electricity generation capabilities than Shewanella oneidensis MR-1 (SO) were uncovered using the developed MFC array, with one environmental electricigen, Shewanella sp. Hac353 (dq307734.1)(7Ca), showing 2.3-fold higher power output than SO. The second MFC array platform developed is an air-cathode MFC array using oxygen in air as electron acceptor, which is sustainable compared to ferricyanide that depletes over time. Environmental electricigen screenings were also conducted, showing parallel comparison capabilities of the developed array. The third MFC array platform is a microfluidic-cathode MFC array that enables long-term operations of miniature MFC arrays with improved power generation abilities. The capability of the microfluidic-cathode MFC array to support long-term parallel analysis was demonstrated by characterizing power generation of SO and 7Ca, proving extended operation time and improved power outputs compared to batch-mode MFC array. The fourth MFC array platform enables both catholyte and anolyte replenishments for long-term characterization of various carbon substrate performances. Finally, the 24-well microfluidic MFC array was further scaled up to 96 wells, which greatly increased the throughput of MFC parallel studies. The developed MFC arrays as high throughput screening platforms are expected to greatly impact how current MFC studies are conducted and ultimately lead to significant improvement in MFC power output.