A dual-photoelectrode fuel cell-driven self-powered aptasensor based on the 1D/2D In2S3/MoS2@Fe-CNTs heterojunction for the ultrasensitive detection of Staphylococcus aureus

A novel dual-electrode photo-fuel cell (PFC)-driven self-powered aptasensor was manufactured for the sensitive and selective detection of Staphylococcus aureus (S. aureus) using the one-dimensional (1D)/2D Schottky heterojunction comprising bimetallic indium/molybdenum sulfide nanosheets and iron-doped carbon nanotube (Fe-CNT) (denoted as In₂S₃/MoS₂@Fe-CNTs) as the photocathode. Given the generation of a robust interface at In₂S₃/MoS₂ and Fe-CNTs, the charge separation and transfer ability of photoexcited electron-hole pairs were enforced, thus improving the output voltage of the assembled PFC. In addition, the numerous active sites of the 1D/2D In₂S₃/MoS₂@Fe-CNTs Schottky heterojunction enabled the immobilization of large amounts of aptamer. Accordingly, the proposed PFC-driven self-powered aptasensor exhibited a wide linear range in 10-1 × 10⁷ CFU mL^-1 with a detection limit of 1.2 CFU mL^-1 toward S. aureus. High selectivity, excellent reproducibility, good stability, and acceptable regenerability, as well as great potential practicality, were also achieved for the detection of S. aureus using the developed PFC-driven self-powered aptasensor. This work not only provides a new photoactive material based on a robust 1D/2D Schottky heterojunction, but also constructs a novel PFC-based self-powered aptasensing strategy based on dual-photoelectrodes and with satisfactory performance for the detection of foodborne pathogens in diverse environments.

Photocatalytic Fuel Cell-Assisted Molecularly Imprinted Self-Powered Sensor: A Flexible and Sensitive Tool for Detecting Aflatoxin B1

The self-powered electrochemical sensor has gained big achievements in energy and devices, but it is challenging in analytical application owing to its low energy conversion efficiency and limited selectivity caused by the plentiful interference in actual samples. Herein, a new self-powered biosensor was constructed by the integration of a photocatalytic fuel cell (PFC) with a molecular imprinting polymer (MIP) to achieve sensitive and specific detection of aflatoxin B1 (AFB₁). Compared with other fuel cells, the PFC owns the advantages of low cost, high energy, good stability, and friendly environment by using light as the excitation source. MoS₂-Ti₃C₂T_x MXene (MoS₂-MX) served as the photoanode material for the first time by forming a heterojunction structure, which can enhance the photocurrent by about 3-fold and greatly improve the photoelectric conversion efficiency. Aiming at the poor selectivity of the self-powered sensor, the MIP was introduced to achieve the specific capture and separation of targets without sample pretreatment. Using the MIP and PFC as recognition and signal conversion elements, respectively, the proposed self-powered biosensor showed a wide dynamic range of 0.01-1000 ng/mL with a detection limit of 0.73 pg/mL, which opened opportunities to design more novel self-powered biosensors and promoted its application in food safety and environmental monitoring.

A dual-photoelectrode photofuel cell based self-powered aptasensor using a multimeter as a direct visual readout strategy

A self-powered aptasensor based on a dual-photoelectrode photofuel cell, whose maximum power density and open circuit potential respectively reached 10.77 μW cm-2 and 0.664 V, was proposed combined with a digital multimeter as a direct visual readout strategy, providing a meaningful perspective for miniaturized, implantable, and on-site sensors.

Self-Powered Detection of Glucose by Enzymatic Glucose/Oxygen Fuel Cells on Printed Circuit Boards

Monitoring glucose levels in physiological fluids can help prevent severe complications associated with hypo- and hyper-glycemic events. Current glucose-monitoring systems require a three-electrode setup and a power source to function, which can hamper the system miniaturization to the patient discomfort. Enzymatic fuel cells (EFCs) offer the opportunity to develop self-powered and minimally invasive glucose sensors by eliminating the need for an external power source. Nevertheless, practical applications demand for cost-effective and mass-manufacturable EFCs compatible with integration strategies. In this study, we explore for the first time the use of gold electrodes on a printed circuit board (PCB) for the development of an EFC and demonstrate its application in saliva. To increase the specific surface area, the PCB gold-plated electrodes were modified with porous gold films. At the anode, glucose oxidase is immobilized with an osmium redox polymer that serves as an electron-transfer mediator. At the cathode, bilirubin oxidase is adsorbed onto the porous gold surface with a blocking agent that prevents parasitic reactions while maintaining the enzyme catalytic activity. The resulting EFC showed a linear response to glucose in phosphate buffer within the range 50 μM to 1 mM, with a sensitivity of 14.13 μA cm-2 mM-1. The sensor was further characterized in saliva, showing the linear range of detection of 0.75 to 2 mM, which is within the physiological range, and sensitivity of 21.5 μA cm-2 mM-1. Overall, this work demonstrates that PCBs are suitable platforms for EFCs, paving the way for the development of fully integrated systems in a seamless and miniaturized device.

Carbon-Encapsulated Iron Nanoparticles as a Magnetic Modifier of Bioanode and Biocathode in a Biofuel Cell and Biobattery

This work demonstrates the application of magnetic carbon-encapsulated iron nanoparticles (CEINs) for the construction of bioelectrodes in a biobattery and a biofuel cell. It has been shown that carbon-encapsulated iron nanoparticles are a suitable material for the immobilization of laccase (Lc) and 1,4-naphthoquinone (NQ) and fructose dehydrogenase (FDH). The system is stable; no leaching of the enzyme and mediator from the surface of the modified electrode was observed. The onset of the catalytic reduction of oxygen to water was at 0.55 V, and catalytic fructose oxidation started at −0.15 V. A biobattery was developed in which a zinc plate served as the anode, and the cathode was a glassy carbon electrode modified with carbon-encapsulated iron nanoparticles, laccase in the Nafion (Nf) layer. The maximum power of the cell was ca. 7 mW/cm2 at 0.71 V and under external resistance of 1 kΩ. The open-circuit voltage (OCV) for this system was 1.51 V. In the biofuel cell, magnetic nanoparticles were used both on the bioanode and biocathode to immobilize the enzymes. The glassy carbon bioanode was coated with carbon-encapsulated iron nanoparticles, 1,4-naphthoquinone, fructose dehydrogenase, and Nafion. The cathode was modified with carbon-encapsulated magnetic nanoparticles and laccase in the Nafion layer. The biofuel cell parameters were as follows: maximum power of 78 µW/cm2 at the voltage of 0.33 V and under 20 kΩ resistance, and the open-circuit voltage was 0.49 V. These enzymes worked effectively in the biofuel cell, and laccase also effectively worked in the biobattery.

Energy Solutions for Wearable Sensors: A Review

Wearable sensors have gained popularity over the years since they offer constant and real-time physiological information about the human body. Wearable sensors have been applied in a variety of ways in clinical settings to monitor health conditions. These technologies require energy sources to carry out their projected functionalities. In this paper, we review the main energy sources used to power wearable sensors. These energy sources include batteries, solar cells, biofuel cells, supercapacitors, thermoelectric generators, piezoelectric and triboelectric generators, and radio frequency (RF) energy harvesters. Additionally, we discuss wireless power transfer and some hybrids of the above technologies. The advantages and drawbacks of each technology are considered along with the system components and attributes that make these devices function effectively. The objective of this review is to inform researchers about the latest developments in this field and present future research opportunities.

Visible light mediated self-powered sensing based on target induced recombination of photogenerated carriers

Self-powered sensing platforms have received widespread attention in areas such as portable, wearable and point-of-care devices. Here we reported visible light mediated self-powered electrochemical sensing based on target induced recombination of photogenerated carriers, which has highly sensitive to detect copper ions concentration. We utilized the recombination of photogenerated carriers mechanism to design visible light-responsive Fe₂O₃-CdS n-n heterojunction as photoanode material, which greatly improved the problem of output energy in photocatalytic self-powered sensors. Expectedly, our proposed visible light mediated self-powered electrochemical system has high separation efficiency of photogenerated carriers, which is 8.4 times that in presence of Cu²⁺. Furthermore, this self-powered electrochemical sensing platform used Cu²⁺ induced recombination of photogenerated carriers, showed a clear linear relationship from 1 nM to 5000 nM with an acceptable detection limit of 0.4 nM. This self-powered electrochemical sensing platform with excellent selectivity, accredited reproducibility and believable stability exhibited promising prospects in developing portable sensing devices and detection chip for real-time and rapid monitoring of Cu²⁺.

Development of a Sensitive Self-Powered Glucose Biosensor Based on an Enzymatic Biofuel Cell

Biofuel cells allow for constructing sensors that leverage the specificity of enzymes without the need for an external power source. In this work, we design a self-powered glucose sensor based on a biofuel cell. The redox enzymes glucose dehydrogenase (NAD-GDH), glucose oxidase (GOx), and horseradish peroxidase (HRP) were immobilized as biocatalysts on the electrodes, which were previously engineered using carbon nanostructures, including multi-wall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO). Additional polymers were also introduced to improve biocatalyst immobilization. The reported design offers three main advantages: (i) by using glucose as the substrate for the both anode and cathode, a more compact and robust design is enabled, (ii) the system operates under air-saturating conditions, with no need for gas purge, and (iii) the combination of carbon nanostructures and a multi-enzyme cascade maximizes the sensitivity of the biosensor. Our design allows the reliable detection of glucose in the range of 0.1-7.0 mM, which is perfectly suited for common biofluids and industrial food samples.

Redox Electrochemistry to Interrogate and Control Biomolecular Communication

Cells often communicate by the secretion, transport, and perception of molecules. Information conveyed by molecules is encoded, transmitted, and decoded by cells within the context of the prevailing microenvironments. Conversely, in electronics, transmission reliability and message validation are predictable, robust, and less context dependent. In turn, many transformative advances have resulted by the formal consideration of information transfer. One way to explore this potential for biological systems is to create bio-device interfaces that facilitate bidirectional information transfer between biology and electronics. Redox reactions enable this linkage because reduction and oxidation mediate communication within biology and can be coupled with electronics. By manipulating redox reactions, one is able to combine the programmable features of electronics with the ability to interrogate and modulate biological function. In this review, we examine methods to electrochemically interrogate the various components of molecular communication using redox chemistry and to electronically control cell communication using redox electrogenetics.

A novel self-powered aptasensor for digoxin monitoring based on the dual-photoelectrode membrane/mediator-free photofuel cell

Self-powered sensor is considered as a promising, rapid, portable and miniaturized detection device that can work without external power input. In this work, a novel dual-photoelectrode self-powered aptasensor for digoxin detection was designed on the basis of a photofuel cell (PFC) composed of a black TiO₂ (B-TiO₂) photoanode and a CuBr photocathode in a single-chamber cell. The sensing platform avoided the use of membrane, free mediator, bioactive components and costly metal Pt electrodes. The large inherent bias between the Fermi energy level of B-TiO₂ and that of CuBr improved the electricity output of PFC that the open circuit potential (OCP) and the maximum power density (P_max) reached 0.58 V and 6.78 μW cm^-2 respectively. Based on the excellent output of PFC, digoxin aptamer was immobilized on photoanode as the recognition element to capture digoxin molecules, which realized the high sensitive and selective detection of digoxin. The self-powered aptasensor displayed a broad linear in the range from 10^-12 M to 10^-5 M with a detection limit (3 S/N) of 0.33 pM. This work paved a luciferous way for further rapid, portable, miniaturized and on-site self-powered sensors.

Recent development of biofuel cell based self-powered biosensors

BFC-based SPBs have been used as power sources for other devices and as sensors for detecting toxicity and BOM.

Photo-driven self-powered biosensor for ultrasensitive microRNA detection via DNA conformation-controlled co-sensitization behavior

We developed a photoelectrochemical enzymatic fuel cell-based self-powered biosensing platform for microRNA detection via DNA conformation change-controlled co-sensitization behavior.

Convenient non-invasive electrochemical techniques to monitor microbial processes: current state and perspectives

Real-time electrochemical monitoring in bioprocesses is an improvement over existing systems because it is versatile and provides more information to the user than periodic measurements of cell density or metabolic activity. Real-time electrochemical monitoring provides the ability to monitor the physiological status of actively growing cells related to electron transfer activity and potential changes in the proton gradient of the cells. Voltammetric and amperometric techniques offer opportunities to monitor electron transfer reactions when electrogenic microbes are used in microbial fuel cells or bioelectrochemical synthesis. Impedance techniques provide the ability to monitor the physiological status of a wide range of microorganisms in conventional bioprocesses. Impedance techniques involve scanning a range of frequencies to define physiological activity in terms of equivalent electrical circuits, thereby enabling the use of computer modeling to evaluate specific growth parameters. Electrochemical monitoring of microbial activity has applications throughout the biotechnology industry for generating real-time data and offers the potential for automated process controls for specific bioprocesses.

Tackling the Challenges of Enzymatic (Bio)Fuel Cells

The ever-increasing demands for clean and sustainable energy sources combined with rapid advances in biointegrated portable or implantable electronic devices have stimulated intensive research activities in enzymatic (bio)fuel cells (EFCs). The use of renewable biocatalysts, the utilization of abundant green, safe, and high energy density fuels, together with the capability of working at modest and biocompatible conditions make EFCs promising as next generation alternative power sources. However, the main challenges (low energy density, relatively low power density, poor operational stability, and limited voltage output) hinder future applications of EFCs. This review aims at exploring the underlying mechanism of EFCs and providing possible practical strategies, methodologies and insights to tackle these issues. First, this review summarizes approaches in achieving high energy densities in EFCs, particularly, employing enzyme cascades for the deep/complete oxidation of fuels. Second, strategies for increasing power densities in EFCs, including increasing enzyme activities, facilitating electron transfers, employing nanomaterials, and designing more efficient enzyme-electrode interfaces, are described. The potential of EFCs/(super)capacitor combination is discussed. Third, the review evaluates a range of strategies for improving the stability of EFCs, including the use of different enzyme immobilization approaches, tuning enzyme properties, designing protective matrixes, and using microbial surface displaying enzymes. Fourth, approaches for the improvement of the cell voltage of EFCs are highlighted. Finally, future developments and a prospective on EFCs are envisioned.

A glucose/O2 fuel cell-based self-powered biosensor for probing a drug delivery model with self-diagnosis and self-evaluation

Extending the application of self-powered biosensors (SPB) into the drug delivery field is highly desirable. Herein, a robust glucose/O2 fuel cell-based biosensor is successfully integrated with a targeted drug delivery system to create a self-sustained and highly compact drug delivery model with self-diagnosis and self-evaluation (DDM-SDSE). The glucose/O2 fuel cell-based biosensor firstly performs its diagnostic function by detecting the biomarkers of cancer. The drug delivery system attached on the anode of the glucose/O2 fuel cell can be released during the diagnostic operation to guarantee the occurrence of a therapy process. Accompanied by the therapy process, the glucose/O2 fuel cell-based biosensor can also act as an evaluation component to dynamically monitor the therapy efficacy by analyzing drug-induced apoptotic cells. In addition, the use of an abiotic catalyst largely improves the stability of the glucose/O2 fuel cell without sacrificing the output performance, further ensuring long-time dynamic evaluation as well as highly sensitive diagnosis and evaluation in this DDM-SDSE. Therefore, the present study not only expands the application of SPBs but also offers a promising in vitro "diagnosis-therapy-evaluation" platform to acquire valuable information for clinical cancer therapy.

Flexible plastic, paper and textile lab-on-a chip platforms for electrochemical biosensing

Flexible biosensors represent an increasingly important and rapidly developing field of research. Flexible materials offer several advantages as supports of biosensing platforms in terms of flexibility, weight, conformability, portability, cost, disposability and scope for integration. On the other hand, electrochemical detection is perfectly suited to flexible biosensing devices. The present paper reviews the field of integrated electrochemical bionsensors fabricated on flexible materials (plastic, paper and textiles) which are used as functional base substrates. The vast majority of electrochemical flexible lab-on-a-chip (LOC) biosensing devices are based on plastic supports in a single or layered configuration. Among these, wearable devices are perhaps the ones that most vividly demonstrate the utility of the concept of flexible biosensors while diagnostic cards represent the state-of-the art in terms of integration and functionality. Another important type of flexible biosensors utilize paper as a functional support material enabling the fabrication of low-cost and disposable paper-based devices operating on the lateral flow, drop-casting or folding (origami) principles. Finally, textile-based biosensors are beginning to emerge enabling real-time measurements in the working environment or in wound care applications. This review is timely due to the significant advances that have taken place over the last few years in the area of LOC biosensors and aims to direct the readers to emerging trends in this field.

A chemical/molecular 4-input/2-output keypad lock with easy resettability based on red-emission carbon dots-Prussian blue composite film electrodes

In this work, a resettable 4-input/2-output keypad lock system based on red-emission carbon dots (rCDs) and Prussian blue (PB) modified electrodes was developed. Electrochromic PB layers were first electrochemically deposited on the indium tin oxide (ITO) electrode surface. An admixture of rCDs and chitosan (Chi) was then cast on the surface of PB layers, forming rCDs-Chi/PB film electrodes. UV-vis absorption of the films was sensitive to the applied potential since the blue PB constituent of the films would be transformed to nearly colorless Prussian white (PW) at the reduction potential of -0.2 V and then from PW back to PB at the oxidation potential of 0.4 V, and the transformation between PB and PW would also influence the fluorescence emission of the rCD constituent in the films. The addition of cysteine (Cys) in the testing solution could reduce the PB in the films into PW and generate an amperometric electrocatalytic current at 0.4 V. Meanwhile, the addition of Fe3+ in solution could greatly quench the fluorescence from the rCD component in the films. Thus, the responses of UV-vis absorbance, fluorescence emission and amperometric current of the rCDs-Chi/PB film electrode system exhibited potential-, Cys- and Fe3+-responsive switching properties. Based on the aforementioned work, a combinational logic gate circuit with 3 inputs and 3 outputs was established. In particular, on the same platform, a novel chemical/molecular 4-input/2-output keypad lock with easy resettability was elaborately designed with amperometric current and fluorescence peak intensity as two different types of outputs, so that a higher security level could be achieved.

Integration of Biofuel Cell-Based Self-Powered Biosensing and Homogeneous Electrochemical Strategy for Ultrasensitive and Easy-To-Use Bioassays of MicroRNA

Biofuel cell (BFC)-based self-powered biosensors have attracted substantial attentions because of their unique merits such as having no need for power sources (only two electrodes are needed). More importantly, in case it can also work in a homogeneous system, more efficient and easy-to-use bioassays could come true. Thus, herein, we proposed a novel homogeneous self-powered biosensing strategy via the integration of BFCs and a homogeneous electrochemical method, which was further utilized for ultrasensitive microRNA (miRNA) detection. To construct such an assay protocol, the cathodic electron acceptor [Fe(CN)₆]^3- was entrapped in the pores of positively charged mesoporous silica nanoparticles and capped by the biogate DNAs. Once the target miRNA existed, it would trigger the controlled release of [Fe(CN)₆]^3-, leading to the dramatic increase of the open circuit voltage. Consequently, the "signal-on" homogeneous self-powered biosensor for the ultrasensitive miRNA assay was realized. Encouragingly, the limit of detection for the miRNA-21 assay was down to 2.7 aM (S/N = 3), obviously superior to those of other analogous reported approaches. This work not only provides an ingenious idea to construct the ultrasensitive and easy-to-use bioassays of miRNA but also exhibits a successful prototype of a portable and on-site biomedical sensor.

Enzymatic Fuel Cells: Towards Self-Powered Implantable and Wearable Diagnostics

With the rapid progress in nanotechnology and microengineering, point-of-care and personalised healthcare, based on wearable and implantable diagnostics, is becoming a reality. Enzymatic fuel cells (EFCs) hold great potential as a sustainable means to power such devices by using physiological fluids as the fuel. This review summarises the fundamental operation of EFCs and discusses the most recent advances for their use as implantable and wearable self-powered sensors.

Light-driven self-powered biosensor for ultrasensitive organophosphate pesticide detection via integration of the conjugated polymer-sensitized CdS and enzyme inhibition strategy

A new light-driven self-powered biosensor based on a photoelectrochemical enzymatic fuel cell was proposed for the ultrasensitive detection of organophosphate pesticides.

Enzymatic biofuel cell-based self-powered biosensing of protein kinase activity and inhibition via thiophosphorylation-mediated interface engineering

We developed a facile and ultrasensitive EBFC-based self-powered biosensor of protein kinase A activity and inhibition via thiophosphorylation-mediated interface engineering.

Design and Experimental Verification of a 0.19 V 53 μW 65 nm CMOS Integrated Supply-Sensing Sensor With a Supply-Insensitive Temperature Sensor and an Inductive-Coupling Transmitter for a Self-Powered Bio-sensing System Using a Biofuel Cell

In this paper, we present a self-powered bio-sensing system with the capability of proximity inductive-coupling communication for supply sensing and temperature monitoring. The proposed bio-sensing system includes a biofuel cell as a power source and a sensing frontend that is associated with the CMOS integrated supply-sensing sensor. The sensor consists of a digital-based gate leakage timer, a supply-insensitive time-domain temperature sensor, and a current-driven inductive-coupling transmitter and achieves low-voltage operation. The timer converts the output voltage from a biofuel cell to frequency. The temperature sensor provides a pulse width modulation (PWM) output that is not dependent on the supply voltage, and the associated inductive-coupling transmitter enables proximity communication. A test chip was fabricated in 65 nm CMOS technology and consumed 53 μW with a supply voltage of 190 mV. The low-voltage-friendly design satisfied the performance targets of each integrated sensor without any trimming. The chips allowed us to successfully demonstrate proximity communication with an asynchronous receiver, and the measurement results show the potential for self-powered operation using biofuel cells. The analysis and experimental verification of the system confirmed their robustness.

Enzymatic Fuel Cell-Based Self-Powered Homogeneous Immunosensing Platform via Target-Induced Glucose Release: An Appealing Alternative Strategy for Turn-On Melamine Assay

Enzymatic fuel cell (EFC)-based self-powered biosensors have attracted considerable attention because of their unique feature of no need for extra power sources during the entire detection process, which endows them with the merits of simplicity, rapidness, low cost, anti-interference, and ease of use. Herein, we proposed, for the first time, an EFC-based self-powered homogeneous immunosensing platform by integrating the target-induced biofuel release and bioconjugate immunoassay for ultrasensitive melamine (ME) detection. In this design, the biofuel, i.e., glucose molecules, was entrapped in the pores of positively charged mesoporous silica nanoparticles and capped by the biogate AuNPs-labeled anti-ME antibody (AuNPs-Ab). The presence of the target ME triggered the entrapped glucose release due to the removal of the biogate via immunoreaction, which resulted in the transfer of electrons produced by glucose oxidation at the bioanode to the biocathode, and thus, the open-circuit voltage of the EFC-based self-powered immunosensor dramatically increased, realizing the ultrasensitive turn-on assay for ME. The limit of detection for ME assay was down to 2.1 pM (S/N = 3), superior to those previously reported in the literature. Notably, real milk samples need no special sample pretreatment for the detection of ME because of the good anti-interference ability of EFC-based self-powered biosensors and the excellent selectivity of the homogeneous immunoassay. Therefore, this appealing self-powered homogeneous immunosensing platform holds great promise as a successful prototype of portable and on-site bioassay in the field of food safety.

A Single-Use, Self-Powered, Paper-Based Sensor Patch for Detection of Exercise-Induced Hypoglycemia

We report a paper-based self-powered sensor patch for prevention and management of exercise-induced hypoglycemia. The article describes the fabrication, in vitro, and in vivo characterization of the sensor for glucose monitoring in human sweat. This wearable, non-invasive, single-use biosensor integrates a vertically stacked, paper-based glucose/oxygen enzymatic fuel cell into a standard Band-Aid adhesive patch. The paper-based device attaches directly to skin, wicks sweat by using capillary forces to a reservoir where chemical energy is converted to electrical energy, and monitors glucose without external power and sophisticated readout instruments. The device utilizes (1) a 3-D paper-based fuel cell configuration, (2) an electrically conducting microfluidic reservoir for a high anode surface area and efficient mass transfer, and (3) a direct electron transfer between glucose oxidase and anodes for enhanced electron discharge properties. The developed sensor shows a high linearity of current at 0.02–1.0 mg/mL glucose centration (R² = 0.989) with a high sensitivity of 1.35 µA/mM.

Toward Wearable Energy Storage Devices: Paper-Based Biofuel Cells based on a Screen-Printing Array Structure

A novel paper-based biofuel cell with a series/parallel array structure has been fabricated, in which the cell voltage and output power can easily be adjusted as required by printing. The output of the fabricated 4-series/4-parallel biofuel cell reached 0.97±0.02 mW at 1.4 V, which is the highest output power reported to date for a paper-based biofuel cell. This work contributes to the development of flexible, wearable energy storage device.

On-chip enzymatic microbiofuel cell-powered integrated circuits

A variety of diagnostic and therapeutic medical technologies rely on long term implantation of an electronic device to monitor or regulate a patient's condition. One proposed approach to powering these devices is to use a biofuel cell to convert the chemical energy from blood nutrients into electrical current to supply the electronics. We present here an enzymatic microbiofuel cell whose electrodes are directly integrated into a digital electronic circuit. Glucose oxidizing and oxygen reducing enzymes are immobilized on microelectrodes of an application specific integrated circuit (ASIC) using redox hydrogels to produce an enzymatic biofuel cell, capable of harvesting electrical power from just a single droplet of 5 mM glucose solution. Optimisation of the fuel cell voltage and power to match the requirements of the electronics allow self-powered operation of the on-board digital circuitry. This study represents a step towards implantable self-powered electronic devices that gather their energy from physiological fluids.

Borinic Acid Polymer: Simplified Synthesis and Enzymatic Biofuel Cell Application

A simplified one-pot and less harmful method has been introduced for the synthesis of borinic acid monomer. The corresponding borinic acid polymer (PBA) has been prepared by reversible addition-fragmentation chain transfer polymerization. Property investigations confirm the characteristics of PBA as a new type of "smart material" in the field of thermo-responsive polymer. The potential application of PBA in the field of enzymatic biofuel cell has been illustrated with a wide open circuit potential of 0.92 V.

Ultrasensitive Self-Powered Aptasensor Based on Enzyme Biofuel Cell and DNA Bioconjugate: A Facile and Powerful Tool for Antibiotic Residue Detection

Herein, we reported a novel ultrasensitive one-compartment enzyme biofuel cells (EBFCs)-based self-powered aptasensing platform for antibiotic residue detection. By taking full advantage of the unique features of both EBFCs-based self-powered sensors and aptamers, the as-proposed aptasensing platform has the merits of simple instrumentation, anti-interference ability, high selectivity, and low cost. In this study, DNA bioconjugate, i.e., SiO₂@gold nanoparticles-complementary strand of aptamer (SiO₂@AuNPs-csDNA), was elaborately designed and played a key role in blocking the mass transport of glucose to the bioanode. While in the presence of the target antibiotic, SiO₂@AuNPs-csDNA bioconjugate broke away from the bioanode due to the aptamer recognition of the target. Without the blocking of glucose by the DNA bioconjugate, a significantly elevated open circuit voltage of the EBFCs-based aptasensor was obtained, whose amplitude was dependent on the antibiotic concentration. In addition, this proposed aptasensor was the first reported self-powered aptasensing platform for antibiotic determination and featured high sensitivity owing to the elaborate design of the DNA bioconjugate modified bioanode of EBFC, which was superior to those previously reported in the literature. Furthermore, due to the anti-interference ability and the excellent selectivity of the aptasensor, no special sample pretreatment was needed for the detection of antibiotics in milk samples. Therefore, the proposed EBFCs-based self-powered aptasensor has a great promise to be applied as a powerful tool for on-site assay in the field of food safety.

Self-powered electrochemical systems as neurochemical sensors: toward self-triggered in vivo analysis of brain chemistry

This review highlights recent development of self-powered electrochemical systems for in vivo neurochemical sensing.

The potential use of glucose oxidase-imprinted polymer-coated electrodes for biofuel cells

Enzymatic biofuel cells using molecularly imprinted polymer coated electrodes.