Paper-based Microbial Fuel Cell Research Articles

A wearable, disposable paper-based self-charging power system integrating sweat-driven microbial energy harvesting and energy storage devices

Microbial fuel cell (MFC) technology is constantly pushing its boundaries and advancing in unexpected ways. Integrating non-toxic, storable, spore-forming bacterial cells into a flexible, disposable paper-based MFC platform provides a new route for powering single-use, sweat-based, wearable devices. Even for one-time or short-term operations, however, the MFC performance remains insufficient as an integrated wearable power source that is reliable and practical. This work demonstrates the first example of wearable, sweat-based, disposable self-charging power paper integrating three MFCs as an energy harvester and a solid-state supercapacitor (SC) as an energy storage device. By printing energy harvesting and storing functionalizes on the same piece of paper, the design and fabrication of the system can be revolutionarily simplified while its flexible, wearable, all-in-one papertronic platform will conform to the skin. Horizontal MFC and planar interdigitated SC devices are easily integrated into a single sheet of paper. This hybrid self-powered system generates an outstanding 4 µW/cm2 and 37 µA/cm2 from sweat, stores an excellent 9.81 mF of energy, demonstrates stable capacitive behavior for more than 100 cycles, and possesses superior self-charging characteristics as it can produce a constant discharge of 5.53 µAh. As a proof of concept, the system successfully powered an on-chip light-emitting diode (LED).

A sweat-activated, wearable microbial fuel cell for long-term, on-demand power generation

In this work, we enabled on-demand, long-functioning, sweat-based power generation through a wearable paper-based microbial fuel cell (MFC) using a novel spore-forming biocatalyst, Bacillus subtilis. The MFC is sustainable and survivable even in the extreme environmental conditions of human skin. B. subtilis, usually found on the skin, was able to form endospores that endure extreme dryness or nutrient limitation when sweat access was limited or unpredictable for humans at rest, offering long-term operation and stable storage. When human sweat was introduced, spore germination and gradual power generation were observed without adding nutrient germinants. Through repeated sporulation and germination depending on the sweat availability, B. subtilis provided a sustainable solution for an innovative sweat-activated power source that can result in the long-lasting vision of self-sustaining wearable electronics. Even after the 48-h operation, the device generated a maximum power density of 24 μW/cm2 and a maximum current density of 175 μA/cm2, which is comparable to or even higher than the previously reported paper-based MFCs using well-known strong exoelectrogens in an optimized bacterial medium. Furthermore, B. subtilis in sweat was shown to be commensal with other skin microorganisms while producing antibiotic substances that were effective against potential pathogens, exhibiting a great potential for seamless and intimate integration with skin-mountable applications.

Sorting the main bottlenecks to use paper-based microbial fuel cells as convenient and practical analytical devices for environmental toxicity testing

Three of the primary bottlenecks, which should be consider for practical, point-of-need use of microbial fuel cell (MFC) analytical devices were surpassed in this work: i) the use of a diffusive barrier, hence, an electrogenic biofilm; ii) longer enrichment/stabilization times to produce a biofilm, made in a laboratory environment, over the electrode; and iii) difficulty comparing results obtained from MFCs based on electrogenic biofilms with standardized bioassays, a setback to be adopted as a new method. Here we show an easy way to determine water toxicity employing planktonic bacteria as biorecognition agents. The paper-based MFC contain an electron carrier (or mediator) to facilitate charge transfer from bacteria to the anode. In this way, there is no need to use biofilms. As far as we know this is the first paper-based MFC containing P. putida KT2440, a well characterized non-pathogenic bacteria previously used in standardized water toxicity bioassays. Results were obtained in 80 min and an effective concentration 50 of 9.02 mg L−1, calculated for Zn2+ (a reference toxic agent), was successfully compared with previously published and ISO standardized bioassays, showing a promising future for this technology. The practical design and cost (less than one U.S. dollar) of the paper-based MFC toxicity test presented will open new market possibilities for rapid and easy-to-use MFC analytical devices.

Origami Microfluidic Microbial Fuel Cell for Powering Iot Node with Iot Cloud Platform

Microbial fuel cells (MFCs) are bio-electrochemical devices that produce electrical current from the electrochemically active bacteria (EABs). These bacteria generate the electrons from the degraded organic matter and harness renewable and pollution-free energy in a self-sustaining manner. Due to its user-friendly architecture, neutral pH, simple operating conditions and amenability to integrate with the on-chip technology, MFCs are the economical and convenient alternative to conventional power sources. Since the first development of MFC, an ample amount of studies have been reported especially to harness new bacteria types, inoculation protocols, and cell and bioelectrode fabrication methodologies. As a result, several MFCs have been successfully developed as a biosensor and power hub by utilizing various fluid resources, such as domestic and industrial wastewater, urine, and soiled water from sewage. However, in order to be commercially viable, the device architecture and size of the MFCs become the essential parameter for power generation, which decides the potential application. In this context, several micro-scale MFC architectures have been proposed. Among these, the paper-based microfluidic fuel cell technology has drawn remarkable attention due to its inexpensive and inherent fluid flow capillary action properties. In addition, wide array (series/parallel) configurations have been incorporated to further enhance the power output.With these MFCs, a extensive range of applications, such as powering LEDs, digital thermometer, wireless, sensors, radio nodes etc., have been successfully demonstrated. With this flexibility and unique features, paper-based MFCs have the ability to monitor the on-field parameter (temperature, humidity, hazardous gas etc.) using the Internet of Things (IoT) cloud network. Currently, The Internet of Things (IoT) technology is the most popular technology in the field of wireless data transmission with IoT cloud. It connects various devices and their protocols over internet infrastructure which can be monitored, analyzed, and controlled remotely over the internet. It has an immense application in the field of healthcare, agriculture, automotive, and remote sensing sectors.In this study, as a proof of concept, the Shewanella putrefaciens powered stacked origami MFCs have been demonstrated to drive an ultra-low-power (ULP) IoT node to measure the on-field ambient temperature and transmit corresponding data to a mobile phone. The IoT node requires 2.5–3.3 volt for proper operation, therefore a DC-DC booster was used just after the fuel cell to step-up the low voltage. This step-up voltage was further stored in the supercapacitor to supply power to the IoT node in case of a high current requirement. Finally, after powering the IoT node, it sends the temperature data over low-power Bluetooth low energy (BLE) that can be observed by any smartphone supporting Bluetooth 4.0 and nRF connect android app. The detailed stepwise integrated block diagram from MFC to a mobile phone has been displayed in Figure 1. The proposed approach offers autonomous environmental monitoring using paper-based MFC as a viable substitute for conventional power sources. Figure 1: Block diagram of complete setup MFCs powering IoT node which communicates to smartphone and IoT cloud servers Figure 1

Microfluidic paper microbial fuel cell powered by Shewanella putrefaciens in IoT cloud framework

The present work demonstrates a miniaturized, easily fabricated, environment-friendly, and cost-effective Microfluidic Paper-based Microbial Fuel Cell (MPMFC) as a potential Energy Harvesting Device. The device consists of a microchannel with a reductant (Shewanella putrefaciens exoelectrogen bacterium with L.B Broth) and oxidant (aerated tap water) flowing over Carbon electrode (anode) and Silver electrode (cathode) using co-laminar flow with the self-capillary phenomenon. The electrochemical analysis like Polarization, Open Circuit Voltage (OCV) was evaluated using a potentiostat, and conductivity and sheet resistance were evaluated using a four-point probe instrument. Various bacterial studies, like growth curve study (Optical Density), volumetric concentrations, and incubation time, were carried out to find out the best suitable optimal bacterial conditions. Lastly, detailed element composition study and morphology of the surface of the electrode with biofouling was carried out using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) techniques, respectively. The portable MPMFC yields a maximum power density of 15.4 μW/cm2 (1340 nA/cm2) at 390 mV over 90 μL of culture. Also, An Internet of Things (IoT)/cloud-based hardware has been developed and integrated with MPMFC platform to observe the real-time device performance leading to its long-lasting potential to operate miniaturized microelectronics sensors and portable devices.

A Portable, Single-Use, Paper-Based Microbial Fuel Cell Sensor for Rapid, On-Site Water Quality Monitoring.

Human access to safe water has become a major problem in many parts of the world as increasing human activities continue to spill contaminants into our water systems. To guarantee the protection of the public as well as the environment, a rapid and sensitive way to detect contaminants is required. In this work, a paper-based microbial fuel cell was developed to act as a portable, single-use, on-site water quality sensor. The sensor was fabricated by combining two layers of paper for a simple, low-cost, and disposable design. To facilitate the use of the sensor for on-site applications, the bacterial cells were pre-inoculated onto the device by air-drying. To eliminate any variations, the voltage generated by the microorganism before and after the air-drying process was measured and calculated as an inhibition ratio. Upon the addition of different formaldehyde concentrations (0%, 0.001%, 0.005%, and 0.02%), the inhibition ratios obtained were 5.9 ± 0.7%, 6.9 ± 0.7%, 8.2 ± 0.6%, and 10.6 ± 0.2%, respectively. The inhibition ratio showed a good linearity with the formaldehyde concentrations at R2 = 0.931. Our new sensor holds great promise in monitoring water quality as a portable, low-cost, and on-site sensor.

A fully disposable 64-well papertronic sensing array for screening electroactive microorganisms

A papertronic 64-well sensing array for rapid and sensitive screening of electroactive microorganisms was developed. This device offers a simple and facile approach to accurately characterize and simultaneously monitor bacterial electrogenicity without complicated fluidic feeding systems and electrical wires. After use, the entirely paper-based device platform can be disposed of safely by incineration without posing a risk of bacterial infection. Paper-based printed circuit boards integrated into the array effectively measured bioelectricity generated from spatially distinct 64 microbial fuel cells (MFCs) without cumbersome electrical connections. The flexible array performed stably through repeated folding cycles. Within 30 min, we successfully determined electrogenicity of 15 bacteria including two known wild-type electroactive microorganisms and thirteen isogenic mutants of P. aeruginosa. The paper-based MFC array could help transform electromicrobial technology from bench-top settings to practical applications that would demand proof of high performance.

Internet of Things temperature sensor powered by bacterial fuel cells on paper

The present work deals with a frugal paper-based microbial fuel cell (PMFC) that generates an average power of 25 μW per device using Shewanella putrefaciens. Bacteria colonized on the paper matrix can be activated by readily available nutrient sources leading to instant power generation. Current study translates this technology to energize a wireless Internet of Things (IoT) sensor. A well-designed stacking of multiple cells is adopted to boost the power output. The power profile characteristics of three 10-unit PMFC configurations namely series (C1), parallel (C2), and combination of both (C3) are investigated. Attempts to directly charge a supercapacitor using serially-connected PMFC stack results in voltage reversal (VR). Hence, to harvest this microbial energy prudently, a customized power management system consisting of integrated Maximum Power Point Tracking (MPPT) feature is deployed. This helps in interfacing the PMFCs to capture charge, boost the harvested voltage and to prevent voltage reversal (VR). Power harvested from PMFCs is stored into a supercapacitor in order to drive the wireless IoT sensor module, which in turn measures temperature and communicates the data to a smart phone. The current endeavours can pave the way for “bacteria powered IoT devices” by unlocking the potential of microbes through PMFCs.

A disposable water-activated paper-based MFC using dry E. coli biofilm

A novel, portable, and disposable paper-based microbial fuel cells (MFC) generating electricity from harmless strain of Escherichia coli (E. coli) has been developed. This MFC is on-demand electricity generation activated by a drop of tap water in a dry anode containing the biofilm of E. coli. A low-cost, simple-structure MFC case was created by a single layer of paper filter with high order of folding, which could support interchangeable dry bacteria-loaded anodes. The paper filter was innovatively engineered to make an integrated air-cathode proton exchange membrane (ACPEM) by coating carbon nanotube mixed with potassium ferricyanide on one surface and spraying hydrophobic solution on the other surface, respectively. The E. coli biofilm pre-inoculated in the anodes made of activated carbon sheet was simply dried in the air for the sake of long-term storage and usage. The dry anodes can be simply set in the MFC case with the readily prepared ACPEM, which can be used for on-demand power generation within seconds after adding water with maximum power density of 8.8μW/cm2.

Passive Feeding in Paper-Based Microbial Fuel Cells

Microbial fuel cells (MFCs) are often constructed using materials such as plastic that can be hazardous to the environment. Building MFCs from paper is a sustainable option, making the fuel cells lightweight and easy to carry. Transported in the bottom of luggage until needed they could be used as backup power supplies in remote locations. Ideally, they would extract nutrients from the environment without needing input from the operator, particular if the user was injured. The current study looked at different paper MFC designs to observe whether they could produce useful power after simply being dropped onto liquid puddles containing organic matter. The results showed that both flat and 3D MFCs could generate current when dropped onto liquid without any need for physical feeding. The 3D tetrahedron MFCs generated power for over 2 weeks with the output sufficient for useful applications such as broadcasting via a transceiver.

Passive Feeding in Paper-Based Microbial Fuel Cells

The versatility of Microbial fuel cells (MFCs) has meant that the technology can now branch towards a growing variety of applications. One of the big challenges however, has not been the microbial community but the identification of materials that allow the organisms to thrive and ultimately produce power. Paper has recently been adopted as a viable material that functions both structurally and as the medium for proton exchange. To date; the most reported use for paper-based MFCs has been as a diagnostics tool, however it is highly desirable to develop paper MFCs as lightweight, portable power supplies. In a diagnostic role, the paper MFCs reported have been low-power and short-lived (lasting just minutes) which is not suitable if the role were as power supply. There have been reports of longer-term electrical outputs using paper-based MFCs (with air-cathodes) such as origami stacks1 and 3D-tetrahedron MFCs2. However, in both cases the method for feeding was via careful liquid injection. This is all very well in a lab-based environment but in a real-world scenario MFCs might need activating quickly and without delicate feeding requirements. Here it would be advantageous to simply distribute onto pools of liquid and have them passively intake the fuel. The goal of the current study therefore was to look at paper-based MFCs and investigate whether they might be able to passively intake nutrients from the surrounding environment. Two MFC designs were looked at; the first being flat 2D-MFCs with the anode on the underside of the paper, directly in contact with the liquid and the cathode on top, open to air. The second design was 3D-tetrahedron MFCs constructed from standard copier paper but with an absorbent cellulose material incorporated into the base. For all MFCs, air-cathodes were used without platinum or ferricyanide. For the 2D-flat MFCs, two methodologies were tested; the first was to print electrodes on either side of the paper and the second were hand-made, three-layered structures with conductive latex cathodes painted on one side and a sheet of carbon fibre adhered to the other. Each MFC was approximately 2cm x 4cm. In all experiments, there was no inoculation prior to the MFC being placed on puddles of enriched wastewater. The MFCs with printed electrodes reached peak OCV of 300mV which quickly dropped. In closed circuit the current peaked at 2.4 µA before rapidly declining which is clearly unsuitable for real-world use. The reason for the poor performance was the dissolution of the electrode as the liquid displaced the conductive elements as verified by the significant increase in resistance after use. Further work with printed MFCs will investigate incorporating a stabilising material to prevent the electrodes dissolving. The flat hand-made MFCs fared much better. Interestingly the conductive-latex cathodes were more resistive than the printed ones yet the MFCs were superior and more stable over time. These MFCs climbed and stabilised for 4 days at 11 µW (185mV). Different types of paper were trialled including baking, greaseproof and copier and all performed comparably. Further work will investigate stacking multiple flat-MFCs on single sheets of paper. The simple flat-MFCs are promising but for MFCs operating outside and tapping into nutrients in puddles they should ideally have enclosed chambers housing the anode. To trial this, 3D-tetrahedron MFCs with 15mL volume were set up to sit on pools of liquid with the only method of feeding via capillary motion of the absorbent base. The 3D-MFCs with absorbent bases were compared to MFCs with a waterproof coating over their base. Those with the absorbent bottoms immediately generated a current and continued increasing in power for over 2 weeks peaking and stabilising at 40µW (2.7 W/m3). In addition, when fresh nutrient was added to the reservoir (not directly to the MFCs), they responded almost immediately, a factor that could be advantageous if the role were biosensor. The MFCs with plastic coated bases showed no working voltage throughout the period. The output generated by the MFCs relying on a passive feeding mechanism is comparable to that produced by the same MFCs with sealed bases from a previous study (where injection feeding took place2). This output is sufficient to initiate a power management system and broadcast radio signals. These findings are an exciting development because lightweight paper-MFCs could potentially be dropped onto puddles of organic liquid, passively sucking up nutrients from the environment and subsequently broadcasting distress signals. References 1Fraiwan et al., (2016) Biosens Bioelectron 85: 190-197 2Winfield et al., (2015) J Mater Chem A 13: 7058-7065

On-Demand Micro-Power Generation from an Origami-Inspired Paper Biobattery Stack

We use origami to create a compact, scalable three-dimensional (3-D) biobattery stack that delivers on-demand energy to the portable biosensors. Folding allows a two-dimensional (2-D) paper sheet possessing predefined functional components to form nine 3-D microbial fuel cells (MFCs), and connect them serially within a small and single unit (5.6 cm × 5.6 cm). We load the biocatalyst Pseudomonas aeruginosa PAO1 in predefined areas that form the MFCs, and freeze-dry them for long-term storage. The biobattery stack generates a maximum power and current of 20 μW and 25 μA, respectively, via microbial metabolism when the freeze-dried cells are rehydrated with readily available wastewater. This work establishes an innovative strategy to revolutionize the fabrication, storage, operation, and application of paper-based MFCs, which could potentially make energy available even in resource-limited settings.

A solvent-free microbial-activated air cathode battery paper platform made with pencil-traced graphite electrodes

We present the fabrication of an ultra-low cost, disposable, solvent-free air cathode all-paper microbial fuel cell (MFC) that does not utilize any chemical treatments. The anode and cathode were fabricated by depositing graphite particles by drawing them on paper with a pencil (four strokes). Hydrophobic parchment paper was used as a proton exchange membrane (PEM) to allow only H+ to pass. Air cathode MFC technology, where O2 was used as an electron acceptor, was implemented on the paper platform. The bioelectric current was generated by an electrochemical process involving the redox couple of microbial-activated extracellular electron transferred electrons, PEM-passed H+, and O2 in the cathode. A fully micro-integrated pencil-traced MFC showed a fast start-time, producing current within 10 s after injection of bacterial cells. A single miniaturized all-paper air cathode MFC generated a maximum potential of 300 mV and a maximum current of 11 μA during 100 min after a single injection of Shewanella oneidensis. The micro-fabricated solvent-free air cathode all-paper MFC generated a power of 2,270 nW (5.68 mW/m2). The proposed solvent-free air cathode paper-based MFC device could be used for environmentally-friendly energy storage as well as in single-use medical power supplies that use organic matter.

A stackable, two-chambered, paper-based microbial fuel cell

We developed a stackable and integrable paper-based microbial fuel cell (MFC) for potentially powering on-chip paper-based devices. Four MFCs were prepared on a T-shaped filter paper which was eventually folded three times to connect these MFCs in series. Each MFC was fabricated by sandwiching multifunctional paper layers for two-chambered fuel cell configuration. One drop of bacteria-containing anolyte into the anodic inlet and another drop of potassium ferricyanide for cathodic reaction flowed through patterned fluidic pathways within the paper matrix, both vertically and horizontally, reaching each of the four MFCs and filling the reservoir of each device. Bacterial respiration then transferred electrons to the anode, which traveled across an external load to the cathode where they combined with protons. The MFC stack connected in series generated a high power density (1.2μW/cm2), which is two orders of magnitude higher than the previous report on the paper-based MFC stack. This work will represent the fusion of the art of origami and paper-based MFC technology, which could provide a paradigm shift for the architecture and design of paper-based batteries.

A Multianode Paper-Based Microbial Fuel Cell: A Potential Power Source for Disposable Biosensors

In this paper, we report a multianode paper-based microbial fuel cell (MFC) capable of generating a power density of 28.4 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . This MFC features: 1) flexible multilayered carbon cloth anodes for bacterial attachment and 2) paper reservoirs for holding the anolyte and catholyte for an extended period of time. The hydrophobic barriers in the anodes and paper-based reservoirs were patterned by impregnating and selectively polymerizing photoresist through UV lithography. Upon inoculum/catholyte introduction, a current of 211 μA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was immediately generated. By using the multianode MFC, the power and current densities increased by 5× and 3×, respectively, compared with a single anode one. The paper-based MFC is expected to be a simple and easy-to-use power source for single-use diagnostic biosensors because even sewage or soiled water in a puddle can become an excellent source for operating MFCs and harvesting electricity through bacterial metabolism.

A paper-based microbial fuel cell: Instant battery for disposable diagnostic devices

We present a microfabricated paper-based microbial fuel cell (MFC) generating a maximum power of 5.5μW/cm2. The MFC features (1) a paper-based proton exchange membrane by infiltrating sulfonated sodium polystyrene sulfonate and (2) micro-fabricated paper chambers by patterning hydrophobic barriers of photoresist. Once inoculum and catholyte were added to the MFC, a current of 74μA was generated immediately. This paper-based MFC has the advantages of ease of use, low production cost, and high portability. The voltage produced was increased by 1.9× when two MFC devices were stacked in series, while operating lifetime was significantly enhanced in parallel.