Modification of glass screen printed electrodes with graphene quantum dots for enhanced power output in miniaturized microbial fuel cells

This paper demonstrates screen-printing technique, Glass Screen printed (GSP) on glass layer with Graphene Quantum Dots (GQDs) via drop casting approach to manufacture electrodes for Miniaturized Microbial Fuel Cells (MMFCs). MMFCs are viable options to sustainably operate low-power devices such as sensors, implantable medical devices, etc. However, the technology is still not fully mature for practical applications due to limitations of output power. Materials and design improvements are required for decreasing internal resistance for better electron transfer and improving overall performance. In this work the electrodes manufactured by GSP technique, and anode modified by GQD was tested in MMFC using RO wastewater. It was found that the GQDs increased the surface area to improve electron transfer kinetics at the anode. As a result, GQDs-based GSPEs showed 7.4 times higher power output 332 nW/cm2 compared to its unaltered electrode which displayed a power output of 44.8 nW/cm2. Electrodes made by GSP technique are more durable and less susceptible to biofouling and corrosion compared to conventional methods. The modified anodes further showed sustained output for long term operation.

Benchmarking Power Generation From Multiple Wastewater Electrolytes in Microbial Fuel Cells With 3D Printed Disk-Electrodes

Microbial Fuel Cells (MFCs) have recently gained attention, as they are inexpensive, green in nature, and sustainable. As per the report, by Allied Market Research the global market size of MFCs will increase from $ 264.8 million in 2021 to $ 452.2 million in 2030, growing at a CAGR of 4.5%. The present work is a comparative study of various types of electrolytes that can be used in MFCs. The working electrodes were printed using conducting graphene-based Polylactic Acid (PLA) filaments with the help of a 3D printer under the principle of the fused deposition method. Simulated electrolytes and natural environmental microbial electrolytes were used here. Also, electrolytes of pure E. coli culture were studied. Lake water reported the highest power density of 8.259 mW/cm2 while Stale E. Coli reported the lowest around 0.184 mW/cm2. The study comprehensively lists potential wastewaters that can fuel the MFCs. With the pioneering of various comparative studies of electrolytes, one can insight into the recruitment of electrolytes with high-performance benchmarks for miniaturized energy storage and other microelectronics applications.

Sustainable circular biorefinery approach for novel building blocks and bioenergy production from algae using microbial fuel cell

The imminent need for transition to a circular biorefinery using microbial fuel cells (MFC), based on the valorization of renewable resources, will ameliorate the carbon footprint induced by industrialization. MFC catalyzed by bioelectrochemical process drew significant attention initially for its exceptional potential for integrated production of biochemicals and bioenergy. Nonetheless, the associated costly bioproduct production and slow microbial kinetics have constrained its commercialization. This review encompasses the potential and development of macroalgal biomass as a substrate in the MFC system for L-lactic acid (L-LA) and bioelectricity generation. Besides, an insight into the state-of-the-art technological advancement in the MFC system is also deliberated in detail. Investigations in recent years have shown that MFC developed with different anolyte enhances power density from several µW/m2 up to 8160 mW/m2. Further, this review provides a plausible picture of macroalgal-based L-LA and bioelectricity circular biorefinery in the MFC system for future research directions.

Recent Advances in Microfluidics-Based Electrochemical Sensors for Foodborne Pathogen Detection

Using pathogen-infected food that can be unhygienic can result in severe diseases and an increase in mortality rate among humans. This may arise as a serious emergency problem if not appropriately restricted at this point of time. Thus, food science researchers are concerned with precaution, prevention, perception, and immunity to pathogenic bacteria. Expensive, elongated assessment time and the need for skilled personnel are some of the shortcomings of the existing conventional methods. Developing and investigating a rapid, low-cost, handy, miniature, and effective detection technology for pathogens is indispensable. In recent times, there has been a significant scope of interest for microfluidics-based three-electrode potentiostat sensing platforms, which have been extensively used for sustainable food safety exploration because of their progressively high selectivity and sensitivity. Meticulously, scholars have made noteworthy revolutions in signal enrichment tactics, measurable devices, and portable tools, which can be used as an allusion to food safety investigation. Additionally, a device for this purpose must incorporate simplistic working conditions, automation, and miniaturization. In order to meet the critical needs of food safety for on-site detection of pathogens, point-of-care testing (POCT) has to be introduced and integrated with microfluidic technology and electrochemical biosensors. This review critically discusses the recent literature, classification, difficulties, applications, and future directions of microfluidics-based electrochemical sensors for screening and detecting foodborne pathogens.

Shewanella putrefaciens powered microfluidic microbial fuel cell with printed circuit board electrodes and soft-lithographic microchannel

Microfluidic microbial fuel cells (μ-MFCs) have received considerable attention due to their ability to generate green and qualitative self-sustainable energy. Several electrodes and device fabrication methodologies, and various electrochemically active bacteria (EABs), along with their effect on MFC performance with various operating parameters, have been well reported. However, shorter life, lower throughput, and high operating and maintenance overheads are major impediments to their development towards commercialization. In this context, simple and cost-effective bioelectrodes using printed circuit board (PCB) and a polymer based microchannel have been fabricated using modern photolithography and soft-lithography techniques respectively. Furthermore, the etched PCB electrodes were patterned with multi-walled carbon nanotubes (MWCNT). Subsequently, these bioelectrodes were assembled over a Y-shaped microchannel and tested under a co-laminar microfluidic flow environment powered by Shewanella putrefaciens. Various volumetric bacterial experiments and flow rate studies have also been conducted to find the most appropriate optimum bacterial volume and power efficiency. Subsequently, extensive potentiometric electrochemical studies, such as Open Circuit Potential (OCP) and polarization analysis, were accomplished using electrochemical workstation. This well-developed handheld μ-MFCs yields a maximum open circuit potential 395 mV with maximum power density of 239.2 μW/cm² (3.271 mA/cm²) at optimized parameters.

Paper-based platforms for microbial electrochemical cell-based biosensors: A review

The development of low-cost analytical devices for on-site water quality monitoring is a critical need, especially for developing countries and remote communities in developed countries with limited resources. Microbial electrochemical cell-based (MXC) biosensors have been quite promising for quantitative and semi-quantitative (often qualitative) measurements of various water quality parameters due to their low cost and simplicity compared to traditional analytical methods. However, conventional MXC biosensors often encounter challenges, such as the slow establishment of biofilms, low sensitivity, and poor recoverability, making them unable to be applied for practical cases. In response, MXC biosensors assembled with paper-based materials demonstrated tremendous potentials to enhance sensitivity and field applicability. Furthermore, the paper-based platforms offer many prominent features, including autonomous liquid transport, rapid bacterial adhesion, lowered resistance, low fabrication cost (<$1 in USD), and eco-friendliness. Therefore, this review aims to summarize the current trend and applications of paper-based MXC biosensors, along with critical discussions on their field applicability. Moreover, future advancements of paper-based MXC biosensors, such as developing a novel paper-based biobatteries, increasing the system performance using an unique biocatalyst, such as yeast, and integrating the biosensor system with other advanced tools, such as machine learning and 3D printing, are highlighted.

Microfluidic Microbial Bioelectrochemical Systems: An Integrated Investigation Platform for a More Fundamental Understanding of Electroactive Bacterial Biofilms

It is the ambition of many researchers to finally be able to close in on the fundamental, coupled phenomena that occur during the formation and expression of electrocatalytic activity in electroactive biofilms. It is because of this desire to understand that bioelectrochemical systems (BESs) have been miniaturized into microBES by taking advantage of the worldwide development of microfluidics. Microfluidics tools applied to bioelectrochemistry permit even more fundamental studies of interactions and coupled phenomena occurring at the microscale, thanks, in particular, to the concomitant combination of electroanalysis, spectroscopic analytical techniques and real-time microscopy that is now possible. The analytical microsystem is therefore much better suited to the monitoring, not only of electroactive biofilm formation but also of the expression and disentangling of extracellular electron transfer (EET) catalytic mechanisms. This article reviews the details of the configurations of microfluidic BESs designed for selected objectives and their microfabrication techniques. Because the aim is to manipulate microvolumes and due to the high modularity of the experimental systems, the interfacial conditions between electrodes and electrolytes are perfectly controlled in terms of physicochemistry (pH, nutrients, chemical effectors, etc.) and hydrodynamics (shear, material transport, etc.). Most of the theoretical advances have been obtained thanks to work carried out using models of electroactive bacteria monocultures, mainly to simplify biological investigation systems. However, a huge virgin field of investigation still remains to be explored by taking advantage of the capacities of microfluidic BESs regarding the complexity and interactions of mixed electroactive biofilms.