Biocompatible Electrodes Research Articles

Electroanalytical overview: the use of laser-induced graphene sensors.

Laser-induced graphene, which was first reported in 2014, involves the creation of graphene by using a laser to modify a polyimide surface. Since then, laser-induced graphene has been extensively studied for application in different scientific fields. One beneficial approach is the use of laser-induced graphene coupled with electrochemistry, where there is a growing need for disposable, conductive, reproducible, flexible, biocompatible, sustainable, and economical electrodes. In this mini overview, we explore the use of laser-induced graphene as the basis of electroanalytical sensors. We first introduce laser-induced graphene, before moving to the use of laser-induced graphene electrodes highlighting the various approaches and different laser parameters used to produce different graphene micro and macro structures, whilst describing how these structures are characterised and benchmarked for those working in the field of laser-induced graphene electrodes for comparison aspects. Next, we turn to the use of laser-induced graphene electrodes as the basis of electrochemical sensing platforms towards key analytes and its use in the development of biosensors. We provide a critical overview of the use of laser-induced graphene sensors compared to screen-printed and additive manufactured electrodes, providing future suggestions for the field.

Neural functional rehabilitation: exploring neuromuscular reconstruction technology advancements and challenges.

Neural machine interface technology is a pioneering approach that aims to address the complex challenges of neurological dysfunctions and disabilities resulting from conditions such as congenital disorders, traumatic injuries, and neurological diseases. Neural machine interface technology establishes direct connections with the brain or peripheral nervous system to restore impaired motor, sensory, and cognitive functions, significantly improving patients' quality of life. This review analyzes the chronological development and integration of various neural machine interface technologies, including regenerative peripheral nerve interfaces, targeted muscle and sensory reinnervation, agonist-antagonist myoneural interfaces, and brain-machine interfaces. Recent advancements in flexible electronics and bioengineering have led to the development of more biocompatible and high-resolution electrodes, which enhance the performance and longevity of neural machine interface technology. However, significant challenges remain, such as signal interference, fibrous tissue encapsulation, and the need for precise anatomical localization and reconstruction. The integration of advanced signal processing algorithms, particularly those utilizing artificial intelligence and machine learning, has the potential to improve the accuracy and reliability of neural signal interpretation, which will make neural machine interface technologies more intuitive and effective. These technologies have broad, impactful clinical applications, ranging from motor restoration and sensory feedback in prosthetics to neurological disorder treatment and neurorehabilitation. This review suggests that multidisciplinary collaboration will play a critical role in advancing neural machine interface technologies by combining insights from biomedical engineering, clinical surgery, and neuroengineering to develop more sophisticated and reliable interfaces. By addressing existing limitations and exploring new technological frontiers, neural machine interface technologies have the potential to revolutionize neuroprosthetics and neurorehabilitation, promising enhanced mobility, independence, and quality of life for individuals with neurological impairments. By leveraging detailed anatomical knowledge and integrating cutting-edge neuroengineering principles, researchers and clinicians can push the boundaries of what is possible and create increasingly sophisticated and long-lasting prosthetic devices that provide sustained benefits for users.

Power-Free Electrochromic System on Smart Contact Lens for Glucose Sensing

Recent advances in wearable electronics incorporating the Internet of Things (IoT) have enabled developments in noninvasive and continuous health monitoring. By real-time analysis of changes in vital signs such as temperature, heart rate, and metabolites including glucose and lactate, early disease diagnosis can be realized. As tear fluid consists of numerous detectable biomarkers, smart contact lenses have been considered one of the most promising wearable devices and have attracted substantial interest in scientific research. It has been reported that tear fluid compositions such as glucose have a close relationship with blood because of the plasma leakage from blood to tear through blood-tear barriers. Compared with the conventional finger-pricking method using a glucometer for diabetes diagnosis, smart contact lenses reduce possible pains and contaminants during blood sample collection. Although great progress has been achieved in investigations on tear glucose monitoring, most of the reported studies mainly focus on electronics like sensors and integrated chips, leading to the necessity of power supplies. Despite the high specific capacity and excellent long-term cyclic performances, conventional lithium-ion batteries cannot be applied to smart contact lenses because of the extremely high safety requirements of eye environments. As an alternative to batteries, inductive power transmission has been widely developed. However, an additional transmitter within an effective distance is always required during the operation, which is inconvenient in particle applications and not applicable for continuous monitoring as well.Here, an electrochromic power-free system for biomonitoring is proposed to reduce the requirements of power supply. Prussian blue (PB), known as one of the promising and biocompatible electrochromic electrodes, was applied to the sensor. Glucose oxidase (GOx) was coated on the surface of the PB electrode for selective detection of glucose. Initially, PB electrodes are at reduced states known as Prussian white (PW), which is transparent. After observing glucose, reactions between glucose and GOx take place, generating the oxidizing agent hydrogen peroxide (H2O2), which oxidizes PW to PB accompanied by an observable color change from transparent to blue. The degree of color change depends on both glucose concentrations and PB thicknesses. Therefore, to enable a wide range of glucose level detection, the sensor with multi-electrode in different thicknesses was designed, with thinner electrodes indicating lower glucose concentration while thicker electrodes working for higher glucose situations. The glucose level can be roughly estimated by the combination of color changes in different electrodes using bare eyes, and more accurate information is accessible by machine learning and image processing. This direct color information thus reduces the requirements of power supplies. Due to inclusions of all required ions for the above redox reactions, tears are able to perform as electrolytes to support normal operations of the electrochromic sensor, eliminating potential risks caused by applications of additional electrolytes.The proposed sensor achieved glucose detection in both the ordinary range (0.16−0.5 mM) and high concentrations (0.9 mM), with a correlation coefficient r = 0.99543 between the predicted results and real concentrations. Lower level glucose detection down to 0.05 mM was also demonstrated. In addition, the recyclability of the sensor was achieved by the implementation of the reduction container, which electrochemically reduced PB to PW in tear-based solutions. The standard deviations of glucose sensing results after 4 repeated detections and several days’ storage were 0.0462 and 0.025, respectively, indicating the consistency of the sensor. We believe that the reported electrochromic power-free sensor has great potential for daily health monitoring and the working principle is not limited to only glucose detection but also suitable for other various metabolites for disease diagnosis. Acknowledgment The content of the presentation has been published as Reference [1]. Reference [1] Z. Li, J. Yun, X. Li, M. Kim, J. Li, D. Lee, A. Wu, S. W. Lee, Power-Free Contact Lens for Glucose Sensing. Adv. Funct. Mater. 2023, 33, 2304647. https://doi.org/10.1002/adfm.202304647 Figure 1

In Vivo Photopolymerization: Achieving Detailed Conducting Patterns for Bioelectronics.

Bioelectronics holds great potential as therapeutics, but introducing conductive structures within the body poses great challenges. While implanted rigid and substrate-bound electrodes often result in inflammation and scarring in vivo, they outperform the in situ-formed, more biocompatible electrodes by providing superior control over electrode geometry. For example, one of the most researched methodologies, the formation of conductive polymers through enzymatic catalysis in vivo, is governed by diffusion control due to the slow kinetics, with curing times that span several hours to days. Herein, the discovery of the formation of biocompatible conductive structures through photopolymerization in vivo, enabling spatial control of electrode patterns is reported. The process involves photopolymerizing novel photoactive monomers, 3Es (EDOT-trimers) alone and in a mixture to cure the poly(3, 4-ethylenedioxythiophene)butoxy-1-sulfonate (PEDOT-S)derivative A5, resulting in conductive structures defined by photolithography masks. These reactions are adapted to in vivo conditions using green and red lights, with short curing times of 5-30min. In contrast to the basic electrode structures formed through other in situ methods, the formation of specific and layered patterns is shown. This opens up the creation of more complex 3D layers-on-layer circuits in vivo.

Bioactive Ion-Confined Ultracapacitive Memristors with Neuromorphic Functions.

The field of bioinspired iontronics, bridging electronic devices and ionic systems, has multiple biological applications. Carbon-based ultracapacitive devices hold promise for controlling bioactive ions via electric double layers due to their high-surface-area and biocompatible porous carbon electrodes. However, the interplay between complex bioactive ions and porous carbons remains unclear due to the variety of structures of bioactive ions present in biological systems. Herein, we investigate the adsorption behavior of a series of bioactive ammonium-based cations with varying alkyl chain lengths in nanoporous carbons. We find that strong physisorption results from the synergistic hydrophobic interaction and electrostatic attraction between porous carbons (with a negative zeta potential) and bioactive cations. Bioactive cations with varying alkyl chain lengths can be irreversibly physically adsorbed and confined within nanoporous carbons resulting in anion enrichment and depletion during electric polarization. This situation, in turn, results in a characteristic memristive behavior in all-carbon capacitive ionic memristor devices. Our findings highlight the relationship between the resistance state of the memristor and ion adsorption mechanisms in all-carbon capacitive devices, which hold potential for future transmitter delivery, biointerfacing, and neuromorphic devices.

Bioactive Ion‐Confined Ultracapacitive Memristors with Neuromorphic Functions

AbstractThe field of bioinspired iontronics, bridging electronic devices and ionic systems, has multiple biological applications. Carbon‐based ultracapacitive devices hold promise for controlling bioactive ions via electric double layers due to their high‐surface‐area and biocompatible porous carbon electrodes. However, the interplay between complex bioactive ions and porous carbons remains unclear due to the variety of structures of bioactive ions present in biological systems. Herein, we investigate the adsorption behavior of a series of bioactive ammonium‐based cations with varying alkyl chain lengths in nanoporous carbons. We find that strong physisorption results from the synergistic hydrophobic interaction and electrostatic attraction between porous carbons (with a negative zeta potential) and bioactive cations. Bioactive cations with varying alkyl chain lengths can be irreversibly physically adsorbed and confined within nanoporous carbons resulting in anion enrichment and depletion during electric polarization. This situation, in turn, results in a characteristic memristive behavior in all‐carbon capacitive ionic memristor devices. Our findings highlight the relationship between the resistance state of the memristor and ion adsorption mechanisms in all‐carbon capacitive devices, which hold potential for future transmitter delivery, biointerfacing, and neuromorphic devices.

Amino Acid Supported Conductive Nanocomposite for Developing Flexible Electrode Material for Energy Storage

Introduction: This study focused on synthesizing biocompatible, flexible and wearable electrode materials for energy storage applications. The unique zwitterionic structure of L-proline provides numerous interesting properties to the nanocomposite such as high ionic interactions through the various ion migration channels, and strong hydration characteristics. These features are key to thehigh performance of energy deposition systems.Methods: Binary nanocomposites containing L-proline (Pro) amino acid and polypyrrole (Ppy) were produced on rGO modified carbon textile (rGO-CC) to develop electroactive materials. Two step hydrothermal method was used to produce flexible electrodes. DRIFT spectroscopy andAFM analysis were performed to clarify the structural and the morphological characterization. Electrochemical behavior was evaluated utilizing CV, GCD and EIS methods.Results: ProPpy@rGO-CC electrode materials exhibit high electrochemical performances in aqueous electrolytes (0.1 M NaCl). The prepared electrode shows high specific capacitance of 500.4 Fg-1 (at 25 mVs−1) at the ambient conditions. Additionally, after 5,000 charge/discharge cycles the specific capacitance retains a high level of 95% confirming the good cycle stability. The energy and the power densities were found to be 278 Wh kg−1 and 12.5 kW kg−1, respectively.Conclusion: The results indicate that the ProPpy@rGO-CC electrode is a promising candidate for next-generation high-performance energy deposition systems. The unique structural features of L-proline contribute to the formation of a large number of electroactive sites and short diffusion pathways.

Synergistic material–microbe interface toward deeper anaerobic defluorination

Per- and polyfluoroalkyl substances (PFAS), particularly the perfluorinated ones, are recalcitrant to biodegradation. By integrating an enrichment culture of reductive defluorination with biocompatible electrodes for the electrochemical process, a deeper defluorination of a C6-perfluorinated unsaturated PFAS was achieved compared to the biological or electrochemical system alone. Two synergies in the bioelectrochemical system were identified: i) The in-series microbial-electrochemical defluorination and ii) the electrochemically enabled microbial defluorination of intermediates. These synergies at the material-microbe interfaces surpassed the limitation of microbial defluorination and further turned the biotransformation end products into less fluorinated products, which could be less toxic and more biodegradable in the environment. This material-microbe hybrid system brings opportunities in the bioremediation of PFAS driven by renewable electricity and warrants future research on mechanistic understanding of defluorinating and electroactive microorganisms at the material-microbe interface for system optimizations.

Ti2TaC2: A novel out-of-plane ordered MXene towards flexible and cytocompatible supercapacitors

Exploring biocompatible and flexible supercapacitor electrode material is crucial for expanding the development of health monitoring bioelectronics. MXene films, due to their low cost, high conductivity, and excellent durability under different deformation conditions, are highly competitive in bioelectronic device applications compared with traditional carbon-based materials. Herein, a novel out-of-plane ordered double transition metal MXene (Ti2TaC2) is elaborately designed and originally synthesized, where Ti atoms preferentially reside in the outer transition metal layer and Ta atoms occupy in the middle layer. Theoretical calculations prove that the introduction of Ta species into Ti3C2 MXene enlarges the work function, raises the d-band center close to Fermi level and increases the density of states of d-orbital. Consequently, the Ti2TaC2 film delivers high specific capacitance of 313 F g−1 at 2 mV s−1 and excellent cycling stability without capacitance loss after 10,000 cycles at 10 A/g. Furthermore, the safety and cytotoxicity of Ti2TaC2 material are innovatively evaluated in vitro multiple cell lines (e.g., 293T, bEnd.3, PC-12, BV2 and HUVEC cells) and implanted into the subcutaneous tissue of mice, proving its good biosafety and cytocompatibility. The results suggest that flexible Ti2TaC2 MXene film may be a promising cytocompatible electrode material for long-term health monitoring bioelectronics.

Highly Biocompatible Graphite Electrodes by Using Interface‐Stable Coating and the Application to Hemodialysis

AbstractIn the treatment of kidney diseases such as chronic kidney disease (CKD) and acute tubular necrosis (ATN), prolonged contact between conductivity sensors and patients' bodily fluids is required, necessitating high biocompatibility for the electrodes. However, the widely used graphite electrodes exhibit limited biocompatibility, showing a cell survival rate of only 88% under indirect contact conditions, and <56% under direct contact conditions. Here, the surface detachment of graphite electrodes in liquid environments leading to cell death upon contact is observed and a solution is proposed to enhance biocompatibility and ensure conductivity, by forming a layer of interface‐stable coating (ISC) as a conductive isolation membrane on their surface. For applications with contact requirements, graphite‐like carbon (GLC) coated graphite electrodes are investigated and developed, resulting in an exceptional cell survival rate exceeding 96% under indirect contact conditions, and a relatively high survival rate exceeding 91% under direct contact conditions, both accompanied by significant proliferation. GLC‐coated graphite electrodes are successfully to monitor the dialysate conductivity in a hemodialysis machine and achieve stable monitoring with temperature compensation. The results demonstrate ISC graphite electrodes' potential in biomedical fluid monitoring, with the developed process applicable to other fields.

Biocompatible supercapacitor engineered from marine collagen impregnated with polypyrrole and tungsten disulfide

There is an urgent demand for highly stable energy storage systems that are biocompatible, environmentally friendly, and made from affordable, sustainable materials. Research on biologically sourced materials as green energy storage devices such as supercapacitor (SC) technologies are emerging, but they are often expensive, complicated to manufacture, and fail to meet the required performance levels. This article presents a simple and innovative method to fabricate a human skin comfortable SC electrode using collagen extracted from hoki (Macruronus novaezelandiae) fish skin. Polypyrrole and tungsten disulfide nanoparticles were incorporated into the collagen matrix via early wetness impregnation to provide the required electrical properties. Electrochemical investigations revealed that the areal capacitance of the composite material was 348 mF cm−2 and cyclic testing showed that the capacitance retention is 98 % after 50,000 cycles. The collagen-based composite demonstrated excellent biocompatibility to HEK293 cells grown over a 1-week period. This novel technique for producing biodegradable and biocompatible SC electrodes from renewable source paves opportunities to utilize other sources of biomaterials for smart electronic applications.

Self‐adhesive and biocompatible dry electrodes with conformal contact to skin for epidermal electrophysiology

AbstractLong‐term biopotential monitoring requires high‐performance biocompatible wearable dry electrodes. But currently, it is challenging to establish a form‐preserving fit with the skin, resulting in high interface impedance and motion artifacts. This research aims to present an innovative solution using an all‐green organic dry electrode that eliminates the aforementioned challenges. The dry electrode is prepared by introducing biocompatible maltitol into the chosen conductive polymer, poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate). Thanks to the secondary doping and plasticizer effect of maltitol, the dry electrode exhibits good stretchability (62%), strong self‐adhesion (0.46 N/cm), high conductivity (102 S/cm), and low Young's modulus (7 MPa). It can always form a conformal contact with the skin even during body movements. Together with good electrical properties, the electrode enables a lower skin contact impedance compared to the current standard Ag/AgCl gel electrode. Consequently, the application of this dry electrode in bioelectrical signal measurement (electromyography, electrocardiography, electroencephalography) and long‐term biopotential monitoring was successfully demonstrated.

Dual-Site Biomacromolecule Doped Poly(3, 4-Ethylenedioxythiophene) for Bosting Both Anticoagulant and Electrochemical Performances.

Poly(3, 4-ethylenedioxythiophene) (PEDOT) as a new generation of intelligent conductive polymers, is attracting much attention in the field of tissue engineering. However, its water dispersibility, conductivity, and biocompatibility are incompatible, which limit its further development. In this work, biocompatible electrode material of PEDOT doped with sodium sulfonated alginate (SS) which contains two functional groups of sulfonic acid and carboxylic acid per repeat unit of the macromolecule. The as dual-site doping strategy simultaneously boosts anticoagulant and electrochemical performances, for example, good hydrophilicity (water contact angle of 59.40°), well dispersibility (dispersion solution unstratified in 30 days), high conductivity (4.45 S m-1), and enhanced anticoagulant property (extended activated partial thrombin time value of 59.0 s), forming an adjustable PEDOT: biomacromolecule interface; this fills the technical gap of implantable bioelectronics in terms of coagulation and thrombosis risk. At the same time, the assembled all-in-one supercapacitor with anticoagulant properties is prepared by PEDOT: sodium sulfonated alginate as electrode material and sodium alginate hydrogel as electrolyte layer. The dual-site doping strategy provides a new opinion for the design and optimization of functional conductive polymers and its applications in implantable energy storage fields.

3D printed PEDOT:PSS-based conducting and patternable eutectogel electrodes for machine learning on textiles

The proliferation of medical wearables necessitates the development of novel electrodes for cutaneous electrophysiology. In this work, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is combined with a deep eutectic solvent (DES) and polyethylene glycol diacrylate (PEGDA) to develop printable and biocompatible electrodes for long-term cutaneous electrophysiology recordings. The impact of printing parameters on the conducting properties, morphological characteristics, mechanical stability and biocompatibility of the material were investigated. The optimised eutectogel formulations were fabricated in four different patterns —flat, pyramidal, striped and wavy— to explore the influence of electrode geometry on skin conformability and mechanical contact. These electrodes were employed for impedance and forearm EMG measurements. Furthermore, arrays of twenty electrodes were embedded into a textile and used to generate body surface potential maps (BSPMs) of the forearm, where different finger movements were recorded and analysed. Finally, BSPMs for three different letters (B, I, O) in sign-language were recorded and used to train a logistic regressor classifier able to reliably identify each letter. This novel cutaneous electrode fabrication approach offers new opportunities for long-term electrophysiological recordings, online sign-language translation and brain-machine interfaces.

Spatially Precise Genetic Engineering at the Electrode-Tissue Interface.

The interface between electrodes and neural tissues plays a pivotal role in determining the efficacy and fidelity of neural activity recording and modulation. While considerable efforts have been made to improve the electrode-tissue interface, the majority of studies have primarily concentrated on the development of biocompatible neural electrodes through abiotic materials and structural engineering. In this study, an approach is presented that seamlessly integrates abiotic and biotic engineering principles into the electrode-tissue interface. Specifically, ultraflexible neural electrodes with short hairpin RNAs (shRNAs) designed to silence the expression of endogenous genes within neural tissues are combined. The system facilitates shRNA-mediated knockdown of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and polypyrimidine tract-binding protein 1 (PTBP1), two essential genes associated in neural survival/growth and neurogenesis, within specific cell populations located at the electrode-tissue interface. Additionally, it is demonstrated that the downregulation of PTEN in neurons can result in an enlargement of neuronal cell bodies at the electrode-tissue interface. Furthermore, the system enables long-term monitoring of neuronal activities following PTEN knockdown in a mouse model of Parkinson's disease and traumatic brain injury. The system provides a versatile approach for genetically engineering the electrode-tissue interface with unparalleled precision, paving the way for the development of regenerative electronics and next-generation brain-machine interfaces.

Highly flexible and transparent amorphous indium doped tin oxide on bio-compatible polymers for transparent wearable sensors

Highly transparent and flexible amorphous Sn-doped In2O3 (a-ITO) films deposited on flexible and bio-compatible cyclic olefin polymer (COP) substrate using a direct-current magnetron sputtering at room temperature were used as flexible and transparent electrodes for transparent wearable sensors. The figure of merits (FoM) value was calculated to determine the optimal sputtering process for the a-ITO electrodes by varying the direct current power, working pressure, oxygen flow rate, and a-ITO thickness. The optimized a-ITO/COP with a high FoM value of 8.9 exhibited a low sheet resistance of 36 Ohm/square, average transmittances of 89.5 % in the visible wavelength region, and a small critical bending radius of 7 mm, which are acceptable transparent electrodes for fabrication of wearable and transparent wearable sensors. To demonstrate the feasibility of the a-ITO/COP substrate as a promising wearable sensor, we examined the performance of wearable temperature sensors, wearable heaters, and wearable glucose sensors. The successful operation of a-ITO/COP-based temperature sensors with high sensitivity, transparent heaters with a saturation temperature of 87.8 °C at 6 V, and glucose sensors with high sensitivity indicates that a-ITO/COP is a promising bio-compatible electrode for next-generation wearable bionic electronics.

Bacterial-Polyhydroxybutyrate for Biocompatible Microbial Electrodes

The development of bioelectrochemical systems requires careful selection of both their biotic and abiotic components to obtain sustainable devices. Herein, we report a biophotoelectrode obtained with polyhydroxybutyrate (PHB), a biopolymer, which purple non-sulphur bacteria produce as an energy stock under specific environmental conditions. The electrode was obtained by casting a mixture composed of PHB and carbon fibers in a 3:2 mass ratio. Following, the composite material was modified with polydopamine and thermally treated to obtain a hydrophilic electrode with improved electrochemical behavior. The bio-based electrode was tested with metabolically active cells of Rhodobacter capsulatus embedded in a biohybrid matrix of polydopamine. The system achieved enhanced catalytic activity under illumination, with an 18-fold increase in photocurrent production compared to biophotoelectrodes based on glassy carbon, reaching a current density of 12 ± 3 μA cm−2, after 30 min of light exposure at +0.32 V. The presented biocompatible electrode provides a sustainable alternative to metal-based and critical raw material-based electrodes for bioelectrochemical systems.

An electrochemical biosensor based on DNA tetrahedron nanoprobe for sensitive and selective detection of doxorubicin

Doxorubicin (DOX) is a clinical chemotherapeutic drug and patients usually suffer from dose-dependent cytotoxic and side effects during chemotherapy process with DOX. Therefore, developing a reliable strategy for DOX analysis in biological samples for dosage guidance during chemotherapy process is of great significance. Herein, a sensitive and selective electrochemical biosensor for DOX detection was designed based on gold nanoparticles (AuNPs) and DNA tetrahedron (TDN) nanoprobe bifunctional glassy carbon electrode that could detect DOX in human serum and cell lysate samples. AuNPs not only could enhance electron transfer efficiency and detection sensitivity, but also could improve the biocompatibility of electrode. TDN nanoprobes were employed as specific DOX bind sites that could bind abundant DOX through intercalative characteristics to contribute to sensitive and selective detection. Under the optimal conditions, the proposed TDN nanoprobes-based DOX biosensor exhibited a wide linear range that ranged from 1.0 nM to 50 μM and a low detection limit that was 0.3 nM. Moreover, the proposed DOX biosensor displayed nice selectivity, reproducibility and stability, and was successfully applied for DOX detection in human serum and cell lysate samples. These promising results maybe pave a way for DOX dosage guidance and therapeutic efficacy optimization in clinic.

High-performing fiber electrodes based on a gold-shelled silver nanowire framework for bioelectronics.

Flexible fiber electrodes offer new opportunities for bioelectronics and are reliable in vivo applications, high flexibility, high electrical conductivity, and satisfactory biocompatibility are typically required. Herein, we present an all-metal flexible and biocompatible fiber electrode based on a metal nanowire hybrid strategy, i.e., silver nanowires were assembled on a freestanding framework, and further to render them inert, they were plated with a gold nanoshell. Our fiber electrodes exhibited a low modulus of ∼75 MPa and electrical conductivity up to ∼4.8 × 106 S m-1. They can resist chemical erosion with negligible leakage of biotoxic silver ions in the physiological environment, thus ensuring satisfactory biocompatibility. Finally, we demonstrated the hybrid fiber as a neural electrode that stimulated the sciatic nerve of a mouse, proving its potential for applications in bioelectronics.

A Wearable Integrated Microneedle Electrode Patch for Exercise Management in Diabetes.

Exercise is one of the preferred management strategies for diabetic patients, but the exercise mode including type, intensity, and duration time is quite different for each patient because of individual differences. Inadequate exercise has no effect on the blood glucose control, while overexercise may cause serious side effects, such as hypoglycemia and loss of blood glucose control. In this work, we report a closed-loop feedback mode for exercise management in diabetes. A minimally invasive, biocompatible microneedle electrode patch was fabricated and used for continuously monitoring the glucose in the interstitial fluid. Further, in conjunction with using a wireless electrochemical device, the glucose signals can be analyzed to output the potency of exercise and give advice on exercise management. A custom exercise given by this closed-loop feedback mode can reduce the used dose of insulin and avoid side effect during and after exercise. We believe that this work can provide a novel comprehensive guidance for diabetic patients.