1,721,250 research outputs found
Sub-millilitre Microbial Fuel Cell Power for Soft Robots
No full textConventional rigid-body robots operate using actuators which differ markedly from the compliant, muscular bodies of biological organisms that generate their energy through organic metabolism. We consider an ‘artificial stomach’ comprised of a single microbial fuel cell (MFC), converting organic detritus to electricity, used to drive an electroactive artificial muscle. This bridges the crucial gap between a bio-inspired energy source and a bio-inspired actuator. We demonstrate how a sub-mL MFC can charge two 1F capacitors, which are then controllably discharged into an ionic polymer metal composite (IPMC) artificial muscle, producing highly energetic oscillation over multiple actuation cycles. This combined bio-inspired power and actuation system demonstrates the potential to develop a soft, mobile, energetically autonomous robotic organism. In contrast to prior research, here we show energy autonomy without expensive voltage amplification
Cast and 3D printed ion exchange membranes for monolithic microbial fuel cell fabrication
Full text linkAbstractWe present novel solutions to a key challenge in microbial fuel cell (MFC) technology; greater power density through increased relative surface area of the ion exchange membrane that separates the anode and cathode electrodes. The first use of a 3D printed polymer and a cast latex membrane are compared to a conventionally used cation exchange membrane. These new techniques significantly expand the geometric versatility available to ion exchange membranes in MFCs, which may be instrumental in answering challenges in the design of MFCs including miniaturisation, cost and ease of fabrication.Under electrical load conditions selected for optimal power transfer, peak power production (mean 10 batch feeds) was 11.39 μW (CEM), 10.51 μW (latex) and 0.92 μW (Tangoplus). Change in conductivity and pH of anolyte were correlated with MFC power production. Digital and environmental scanning electron microscopy show structural changes to and biological precipitation on membrane materials following long term use in an MFC. The cost of the novel membranes was lower than the conventional CEM. The efficacy of two novel membranes for ion exchange indicates that further characterisation of these materials and their fabrication techniques, shows great potential to significantly increase the range and type of MFCs that can be produced
Biodegradation and proton exchange using natural rubber in microbial fuel cells
No full textOne of the constraints holding back microbial fuel cell (MFC) progress is the cost of reactor components. Utilising waste materials could make the technology more desirable opening up the potential for novel niche applications. A costly but vital constituent of the MFC is the IEM (ion exchange membrane), a material prone to failure over time. The current study investigated the use of natural rubber as an alternative to IEM in MFCs. Initially, the material proved impermeable to protons, but gradually a working voltage was generated that improved with time. After 6 months the latex MFC outperformed anion exchange membrane (AEM) but was inferior both in terms of power (109%) and current (16%) to cation exchange membrane (CEM). After 11 months, latex outperformed both commercially available IEMs where power (12%) and current (54%) were higher than CEM. A combination of continuous latex MFC improvement with CEM decline, possibly due to biofouling, was responsible for this superiority. SEM images revealed pores in the used latex suggesting that biodegradation was enabling proton exchange. The research demonstrates for the first time that the biodegradation of a ubiquitous waste material operating as IEM can benefit MFC performance while also improving the reactors lifetime compared to commercially available membranes
Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells
No full textThe long and short-term stability of two porous dependent ion exchange materials; starch-based compostable bags (BioBag) and ceramic, were compared to commercially available cation exchange membrane (CEM) in microbial fuel cells. Using bi-directional polarisation methods, CEM exhibited power overshoot during the forward sweep followed by significant power decline over the reverse sweep (38%). The porous membranes displayed no power overshoot with comparably smaller drops in power during the reverse sweep (ceramic 8%, BioBag 5.5%). The total internal resistance at maximum power increased by 64% for CEM compared to 4% (ceramic) and 6% (BioBag). Under fixed external resistive loads, CEM exhibited steeper pH reductions than the porous membranes. Despite its limited lifetime, the BioBag proved an efficient material for a stable microbial environment until failing after 8 months, due to natural degradation. These findings highlight porous separators as ideal candidates for advancing MFC technology in terms of cost and operation stability
An Energetically-Autonomous Robotic Tadpole with Single Membrane Stomach and Tail
No full textWe present an energetically autonomous robotic tadpole that uses a single membrane component for both electrical energy generation and propulsive actuation. The coupling of this small bio-inspired power source to a bio-inspired actuator demonstrates the first generation design for an energetically autonomous swimming robot consisting of a single membrane. An ionic polymer metal composite (IPMC) with a Nafion polymer layer is demonstrated in a novel application as the ion exchange membrane and anode and cathode electrode of a microbial fuel cell (MFC), whilst being used concurrently as an artificial muscle tail. In contrast to previous work using stacked units for increased voltage, a single MFC with novel, 0.88ml anode chamber architecture is used to generate suitable voltages for driving artificial muscle actuation, with minimal step up. This shows the potential of the small forces generated by IPMCs for propulsion of a bio-energy source. The work demonstrates great potential for reducing the mass and complexity of bio-inspired autonomous robots. The performance of the IPMC as an ion exchange membrane is compared to two conventional ion exchange membranes, Nafion and cation exchange membrane (CEM). The MFC anode and cathode show increased resistance following inclusion within the MFC environment
Row-bot::An energetically autonomous artificial water boatman
No full textWe present a design for an energetically autonomous artificial organism, combining two subsystems; a bio-inspired energy source and bio-inspired actuation. The work is the first demonstration of energetically autonomy in a microbial fuel cell (MFC)-powered, swimming robot taking energy from it's surrounding, aqueous environment. In contrast to previous work using stacked MFC power sources, the Row-bot employs a single microbial fuel cell as an artificial stomach and uses commercially available voltage step-up hardware to produce usable voltages. The energy generated exceeds the energy requirement to complete the mechanical actuation needed to refuel. Energy production and actuation are demonstrated separately with the results showing that the combination of these subsystems will produce closed-loop energetic autonomy. The work shows a crucial step in the development of autonomous robots capable of long term self-power. Bio-inspiration for the design of the Row-bot was taken from the water boatman beetle. This proof of concept study opens many avenues for the further development of the subsystems comprising the Row-bot, and the functionality of the robot itself
The Power of Glove: Soft Microbial Fuel Cell for Low-Power Electronics
Full text linkA novel, soft microbial fuel cell (MFC) has been constructed using the finger-piece of a standard laboratory natural rubber latex glove. The natural rubber serves as structural and proton exchange material whilst untreated carbon veil is used for the anode. A soft, conductive, synthetic latex cathode is developed that coats the outside of the glove. This inexpensive, lightweight reactor can without any external power supply, start up and energise a power management system (PMS), which steps-up the MFC output (0.06–0.17 V) to practical levels for operating electronic devices (>3 V). The MFC is able to operate for up to 4 days on just 2 mL of feedstock (synthetic tryptone yeast extract) without any cathode hydration. The MFC responds immediately to changes in fuel-type when the introduction of urine accelerates the cycling times (35 vs. 50 min for charge/discharge) of the MFC and PMS. Following starvation periods of up to 60 h at 0 mV the MFC is able to cold start the PMS simply with the addition of 2 mL fresh feedstock. These findings demonstrate that cheap MFCs can be developed as sole power sources and in conjunction with advancements in ultra-low power electronics, can practically operate small electrical devices
Tunable, multi-modal, and multi-directional vibration energy harvester based on three-dimensional architected metastructures
Full text linkConventional vibration energy harvesters based on two-dimensional planar layouts have limited harvesting capacities due to narrow frequency bandwidth and because their vibratory motion is mainly restricted to one plane. Three-dimensional architected structures and advanced materials with multifunctional properties are being developed in a broad range of technological fields. Structural topologies exploiting compressive buckling deformation mechanisms however provide a versatile route to transform planar structures into sophisticated three-dimensional architectures and functional devices. Designed geometries and Kirigami cut patterns defined on planar precursors contribute to the controlled formation of diverse threedimensional forms. In this work, we propose an energy harvesting system with tunable dynamic properties, where piezoelectric materials are integrated and strategically designed into three-dimensional compliant architected metastructures. This concept enables energy scavenging from vibrations not only in multiple directions but also across a broad frequency bandwidth, thus increasing the energy harvesting efficiency. The proposed system comprises a buckled ribbon with optional Kirigami cuts. This platform enables the induction of vibration modes across a wide range of resonance frequencies and in arbitrary directions, mechanically coupling with four cantilever piezoelectric beams to capture vibrations. The multi-modal and multi-directional harvesting performance of the proposed configurations has been demonstrated in comparison with planar systems. The results suggest this is a facile strategy for the realization of compliant and high-performance energy harvesting and advanced electronics systems based on mechanically assembled platforms
Toward Energetically Autonomous Foraging Soft Robots
Full text linkA significant goal of robotics is to develop autonomous machines, capable of independent and collective operation free from human assistance. To operate with complete autonomy robots must be capable of independent movement and total energy self-sufficiency. We present the design of a soft robotic mouth and artificial stomach for aquatic robots that will allow them to feed on biomatter in their surrounding environment. The robot is powered by electrical energy generated through bacterial respiration within a microbial fuel cell (MFC) stomach, and harvested using state-of-the-art voltage step-up electronics. Through innovative exploitation of compliant, biomimetic actuation, the soft robotic feeding mechanism enables the connection of multiple MFC stomachs in series configuration in an aquatic environment, previously a significant challenge. We investigate how a similar soft robotic feeding mechanism could be driven by electroactive polymer artificial muscles from the same bioenergy supply. This work demonstrates the potential for energetically autonomous soft robotic artificial organisms and sets the stage for radically different future robots
Here today, gone tomorrow:biodegradable soft robots
Full text linkOne of the greatest challenges to modern technologies is what to do with them when they go irreparably wrong or come to the end of their productive lives. The convention, since the development of modern civilisation, is to discard a broken item and then procure a new one. In the 20th century enlightened environmentalists campaigned for recycling and reuse (R and R). R and R has continued to be an important part of new technology development, but there is still a huge problem of non-recyclable materials being dumped into landfill and being discarded in the environment. The challenge is even greater for robotics, a field which will impact on all aspects of our lives, where discards include motors, rigid elements and toxic power supplies and batteries. One novel solution is the biodegradable robot, an active physical machine that is composed of biodegradable materials and which degrades to nothing when released into the environment. In this paper we examine the potential and realities of biodegradable robotics, consider novel solutions to core components such as sensors, actuators and energy scavenging, and give examples of biodegradable robotics fabricated from everyday, and not so common, biodegradable electroactive materials. The realisation of truly biodegradable robots also brings entirely new deployment, exploration and bio-remediation capabilities: why track and recover a few large non-biodegradable robots when you could speculatively release millions of biodegradable robots instead? We will consider some of these exciting developments and explore the future of this new field
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