Sensor Electrode Research Articles

Enhancing Electrochemical Biosensing of Circulating Nucleic Acids at the Electrode-Biomolecule-Electrolyte Interfaces.

The detection and analysis of circulating cell-free nucleic acid (ccfNA) biomolecules are redefining a new era of molecular targeted cancer therapies. However, the clinical translation of electrochemical ccfNA biosensing remains hindered by unresolved challenges in analytical specificity and sensitivity. In this Perspective, we present a novel electrochemical framework for improving ccfNA biosensor performance by optimizing the critical electrode-biomolecules-electrolyte interfaces. We highlight and elucidate related research works on modification-free electrode sensor surfaces, nucleic acids as biological scaffolds, and redesigning redox reporter systems. We conclude by providing an outlook into the future research developments of ccfNA electrochemical biosensing, emphasizing the potential to overcome current analytical limitations by controlling the complex interplay of target biomolecules and redox species at the electrode surface. These advances are poised to significantly impact the development of electrochemical ccfNA technologies, improving both cancer diagnostics and therapeutic monitoring.

MEMS Pressure Sensors with Novel TSV Design for Extreme Temperature Environments

This study introduces a manufacturing process based on industrial MEMS technology, enabling the production of diverse sensor designs customized for a wide range of absolute pressure measurements. Using monocrystalline silicon as the structural material minimizes thermal stresses and eliminates temperature-dependent semiconductor effects, as silicon functions solely as a mechanical material. Integrating a eutectic bonding process in the sensor fabrication allows for a reliable operation at temperatures up to 350 °C. The capacitive sensor electrodes are enclosed within a silicon-based Faraday cage, ensuring effective shielding against external electrostatic interference. An innovative Through-Silicon Via (TSV) design, sealed using gold–gold (Au-Au) diffusion and gold–silicon (Au-Si) eutectic bonding, further enhances the mechanical and thermal stability of the sensors, even under high-temperature conditions. The unfilled TSV structure mitigates mechanical stress from thermal expansion. The sensors exhibited excellent performance, achieving a linearity of 99.994%, a thermal drift of −0.0164% FS (full scale)/K at full load and 350 °C, and a high sensitivity of 34 fF/kPa. These results highlight the potential of these sensors for high-performance applications across various demanding environments.

Development of Thermoplastic Bi-Component Electrodes for Triboelectric Impact Detection in Smart Textile Applications.

Smart textiles provide a significant technological advancement, but their development must balance traditional textile properties with electronic features. To address this challenge, this study introduces a flexible, electrically conductive composite material that can be fabricated using a continuous bi-component extrusion process, making it ideal for sensor electrodes. The primary aim was to create a composite for the filament's core, combining multi-walled carbon nanotubes (MWCNTs), polypropylene (PP), and thermoplastic elastomer (TPE), optimised for conductivity and flexibility. This blend, suitable for bi-component extrusion processes, exemplifies the role of advanced materials in combining electrical conductivity, mechanical flexibility, and processability, which are essential for wearable technology. The composite optimisation balanced MWCNT (2.5, 5, 7.5, and 10 wt.%) and TPE (0, 25, and 50 wt.%) in a PP matrix. There was a significant decrease in electrical resistivity between 2.5 and 5 wt.% MWCNT, with electrical resistivity ranging from (7.64 ± 4.03)104 to (1.15 ± 0.10)10-1 Ω·m. Combining the composite with 25 wt.% TPE improved the flexibility, while with 50 wt.% TPE decreased tensile strength and hindered the masterbatch pelletising process. The final stage involved laminating the composite filament electrodes, with a 5 wt.% MWCNT/PP/(25 wt.% TPE) core and a TPE sheath, into a textile triboelectric impact detection sensor. This sensor, responding to contact and separation, produced an output voltage of approximately 5 V peak-to-peak per filament and 15 V peak-to-peak with five filaments under a 100 N force over 78.54 cm2. This preliminary study demonstrates an innovative approach to enhance the flexibility of conductive materials for smart textile applications, enabling the development of triboelectric sensor electrodes with potential applications in impact detection, fall monitoring, and motion tracking.

Self-standing block shaped cobalt metal organic frameworks deposited graphite rod electrode for non-enzymatic electrochemical detection of imidacloprid in vegetable and fruit

Neonicotinoid pesticides are increasingly being used in agriculture and farming sectors, which can have hostile effects on the environment and water resources. All living creatures including humans had forcefully consumed from the environment this cancerous neonicotinoid pesticide, imidacloprid. Herein, our study reported a novel free-standing electrochemical sensor for ultrasensitive and discriminatory detection of imidacloprid (IM) pesticide using cobalt metal-organic framework (MOF) anchored graphite rod (GR). The surface structure and morphology of the porous Co(pyrazole dicarboxylic acid)[PZDA]MOFs were systematically investigated after solvothermal growth on graphite rods. Electrochemical experiments revealed noteworthy catalytic activity for Co(PZDA)MOF//GR in reducing imidacloprid. The synergistic effect between GRs and Co(PZDA)MOF significantly improves the electrochemical responses. Electrocatalysis studies displayed reversible diffusion-controlled kinetics of four electrons and four protons involved in the electro-reduction of imidacloprid. Detection of IM by differential pulse voltammetry (DPV) method portrays a wide lined dynamic range (0.01 – 100 µM) with a sensitivity of 83.69 μA μM−1 cm−2 and limit of detection value 4.8 nM. Moreover, Co(PZDA)MOF//GR electrode showed an unique electrocatalytic performance and excellent duplicability, outstanding repeatability, and brilliant storing steadiness up to two months. Thus, the sensor electrode provides a simple, affordable, environmentally friendly, cost-effective imidacloprid detection tool in real-world samples.

Synergistic Effect of Nickel Hydroxide/Hexagonal Boron Nitride Hybrid: An Efficient Electrocatalyst for Detecting 5-Fluorouracil in Human Blood Serum.

5-Fluorouracil (5-Fu) is the third-most often used chemotherapeutic medication and has been scientifically demonstrated to be effective in treating solid tumors, including colorectal, stomach, cutaneous, and breast cancers. When used in excess, it accumulates toxic metabolites, which can have deadly and very harmful effects on people, including neurotoxicity and the induction of morbidity. Therefore, sensitive and rapid analytical techniques for detecting 5-Fu in human blood serum are needed to enhance chemotherapy and forecast the possible adverse effects of 5-Fu residues in the human body. In this report, we developed a simple preparation of three-dimensional/two-dimensional (3D/2D) Nickel hydroxide/hexagonal boron nitride modified with a glassy carbon electrode [Ni(OH)2/h-BN/GCE] for effective electrochemical detection of the 5-fluorouracil with high selectivity. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution scanning electron microscopy (HR-SEM), and HR-Transmission electron microscopy (HR-TEM) were used to characterize the crystalline, structural, and chemical properties of the as-synthesized materials. Moreover, the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), square wave voltammetry (SWV), and i-t curves examined the electrode's electrochemical properties and sensor applications. Therefore, under ideal circumstances, Ni(OH)2/h-BN/GCE demonstrated outstanding 5-Fu selectivity, durability, a low LOD (0.001 μM), and a good linear range (0.02-12 μM). Finally, excellent results were obtained while testing this sensor for 5-Fu sensing in human blood serum.

Laser-Induced Metal-Organic Framework-Derived Flexible Electrodes for Electrochemical Sensing.

The successful development of a metal-organic framework (MOF)-derived Co/Co3O4/C core-shell composite integrated into laser-induced graphitic (LIG) carbon electrodes for electrochemical sensing is reported. The sensors are fabricated via a direct laser scribing technique using a UV laser (355 nm wavelength) to induce the photothermolysis of rationally selected ZIF-67 into the LIG matrix. Electrochemical characterization reveals that the incorporation of the laser-scribed ZIF-67-derived composite on the electrode surface reduces the impedance more than 100 times compared with bare LIG sensors. Comprehensive morphological, structural, and chemical analyses confirm the formation of porous LIG from the laser irradiation of polyimide, while the LIG+ZIF-67-derived composites feature size-controlled and uniformly distributed Co/Co3O4 core/shell nanoparticles (NPs) in the semihollow wasp-nest-like carbon matrix from photothermal decomposition of ZIF-67, embedded within the LIG electrode area. The high surface area and porosity of this ZIF-67-derived nitrogen-rich carbon facilitate charge transfer processes, whereas size-controlled Co/Co3O4 core/shell NPs offer accessible electrochemical active sites, making these LIG+ZIF-67-derived composite-based sensors promising materials for applications requiring high charge injection capability and low electrode/electrolyte interface impedance. The PI+Z67L sensor exhibited a 400 times higher specific capacitance (2.4 mF cm-2) compared to the PIL sensor (6 μF cm-2). This laser scribing approach enables the rapid and cost-effective fabrication of high-performance electrochemical sensors enhanced by the integration of tailored MOF-derived composites.

High-sensitivity and stability electrochemical sensors for chlorogenic acid detection based on optimally engineered nanomaterials.

Developing cost-effective and efficient analytical methods is essential for detecting chlorogenic acid (CGA), as excessive consumption of CGA, despite its significant antioxidant, anticancer, and anti-inflammatory properties, can cause serious health problems. The remarkable progress and adjustable features of nanomaterials have significantly improved the analytical capabilities of electrochemical sensors for CGA. This review examines the use of optimally engineered nanomaterials in CGA electrochemical sensors, emphasizing the design and modification strategies of various nanomaterials. It starts with an introduction to the basic principles of electrochemical sensors, detailing their components and the analytical methods employed. Subsequently, the review explores how structural and compositional adjustments in electrocatalysts from different nanomaterial categories enhance CGA detection performance. In conclusion, it discusses the challenges and opportunities linked to designing nanomaterials for modified electrodes in CGA sensors. This review seeks to enhance the understanding of the connection between nanomaterial structures and the performance of CGA electrochemical sensors, offering new perspectives for the future design of highly efficient CGA electrochemical sensors.

Electrodeposited Ni on a Silk-Derived Carbon modified Glassy Carbon Electrode for Non-Invasive Sensing of Glucose in Saliva

In order to improve the life quality for diabetic patients, a groundbreaking study has designed of a non-invasive sensor capable of monitoring glucose levels in saliva. The non-enzymatic glucose sensor...

Design and fabrication of nitrogen- and sulfur-doped carbon quantum dot-integrated cobalt hexacyanoferrate hybrid sensor electrodes for enhanced dopamine detection

Design and fabrication of nitrogen- and sulfur-doped carbon quantum dot-integrated cobalt hexacyanoferrate hybrid sensor electrodes for enhanced dopamine detection

Hydrothermal synthesis of iron foam-supported Co3O4-based sensor electrodes for electrochemical detection of nitrite

Hydrothermal synthesis of iron foam-supported Co3O4-based sensor electrodes for electrochemical detection of nitrite

Gold Nanoparticle-Modified Molecularly Imprinted Polymer-Coated Pencil Graphite Electrodes for Electrochemical Detection of Bisphenol A.

The sensitive Bisphenol A (BPA) detection by an electrochemical sensor based on gold nanoparticle-doped molecularly imprinted polymer was successfully improved. This study describes the development of a method for BPA detection in both aqueous solution and real water samples using N-methacroyl-(L)-cysteine methyl ester and N-methacryloyl-(L)-phenylalanine methyl ester coated pencil graphite electrodes modified with AuNPs by differential pulse voltammetry (DPV). Importantly, AuNPs, which increase the electroactivity, were used to increase the surface area of a BPA-imprinted pencil graphite electrode (MIP PGE) sensor. Scanning electron microscopy and spectrophotometry analysis were used for the characterization. The DPV response of the synthesized electrode showed distinguished electrical conductivity. The MIP PGE and nonimprinted pencil graphite electrode (NIP PGE) sensor were evaluated for selective and sensitive detection of BPA in aqueous solutions. Five different BPA concentrations (1.5, 3.0, 4.5, 6.0, and 7.5 μM) were applied to the MIP PGE, and the DPV recognized signal responses with a correlation coefficient value of 0.9965. The modified electrode demonstrated good electrocatalytic activity toward BPA for the linear concentration range of 1.5-7.5 μM, and a low limit of detection was found as 0.1610 μM. The results show that the MIP PGE sensor has excellent potential for selective and sensitive detection of BPA in real water samples.

Advanced processing techniques for electric field-guided electrospinning of self-organized Ag nanoparticle electrodes for real-time humidity and temperature sensing

Abstract With the rapid expansion of flexible electronics, there is an urgent need for sustainable production methods that enhance device performance while minimizing environmental impact. This work presents an innovative, green approach for fabricating flexible, patterned electrodes via electric field-driven self-organization of conductive fibers onto flexible substrates. By applying high voltage to both the dispensing nozzle and an underlying printed circuit board (PCB) substrate, the system leverages controlled electric fields to direct fiber jets with precision, eliminating the need for conventional masking techniques. The fiber composition-polyethylene oxide (PEO) integrated with silver nanoparticles-provides both conductivity and environmental compatibility. This streamlined technique notably reduces material usage, processing time, and chemical waste. Practical demonstrations involve the construction of flexible conductive electrodes for humidity and temperature sensors, achieving a low sheet resistance near 10 Ω/sq, attesting to the method’s functional viability. The process ensures precise fiber alignment and consistent deposition, paving the way for its integration into flexible sensor and device applications. This study underscores the potential of electric field manipulation to revolutionize coating processes for sustainable and scalable production in flexible electronics.

Peculiarities of transformations in systems of coordination nitrate precursors of rare earth elements and lithium during the formation of polyfunctional oxide materials

The article summarizes information important for practical use on the conditions of formation, composition, structure, forms of Ln coordination polyhedra, type of ligand coordination, and characteristic properties of lithium coordination nitrates of rare earth elements of the cerium subgroup of the isostructural series Li3[Ln2(NO3)9]∙3H2O (Ln – La–Nd) (predecessors of promising modern multifunctional materials). The obtained data (as primary information) can serve as the basis for identifying, monitoring the phase state of processing objects in the preparatory stages; selection of criteria for the compatibility of components in the formation of single-layer and layered nanostructured oxide systems of lanthanides and transition elements with the structure of defective perovskite, garnet in the form of powders, thick films, bulk ceramics; development of various combined methods of their activation and establishment of technologically functional dependencies; controlled modification of the properties of the target product; optimization of synthesis modes of lithium-conducting systems such as electrodes of rechargeable batteries, electrolyte membranes and sensors, elements and instrument structures of modern telecommunications systems.

Laser-Induced Graphene Electrodes for Flexible pH Sensors.

In the growing field of personalized medicine, non-invasive wearable devices and sensors are valuable diagnostic tools for the real-time monitoring of physiological and biokinetic signals. Among all the possible multiple (bio)-entities, pH is important in defining health-related biological information, since its variations or alterations can be considered the cause or the effect of disease and disfunction within a biological system. In this work, an innovative (bio)-electrochemical flexible pH sensor was proposed by realizing three electrodes (working, reference, and counter) directly on a polyimide (Kapton) sheet through the implementation of CO2 laser writing, which locally converts the polymeric sheet into a laser-induced graphene material (LIG electrodes), preserving inherent mechanical flexibility of Kapton. A uniform distribution of nanostructured PEDOT:PSS was deposited via ultrasonic spray coating onto an LIG working electrode as the active material for pH sensing. With a pH-sensitive PEDOT coating, this flexible sensor showed good sensitivity defined through a linear Nernstian slope of (75.6 ± 9.1) mV/pH, across a pH range from 1 to 7. We demonstrated the capability to use this flexible pH sensor during dynamic experiments, and thus concluded that this device was suitable to guarantee an immediate response and good repeatability by measuring the same OCP values in correspondence with the same pH applied.

Continuous Monitoring of Lithium Ions in Lithium-Rich Brine Using Ion Selective Electrode Sensors Modified with Polyelectrolyte Multilayers of Poly(allylamine hydrochloride)/Poly(sodium 4-styrenesulfonate).

Monitoring lithium ions (Li+) in lithium-rich brine (LrB) is critical for metal recovery, yet challenges such as high ionic strength and gypsum-induced surface deterioration hinder the performance of potentiometric ion-selective electrode (ISE) sensors. This study advances the functionality of Li+ ISE sensors and enables continuous monitoring of Li+ concentration in LrB by introducing apolyelectrolyte multilayer (PEM) of poly(allylamine hydrochloride)/poly(sodium 4-styrenesulfonate) (PAH/PSS) that serves as an antigypsum scaling material to minimize nucleation on the sensor surface. With 5.5 bilayers of PAH/PSS coating, the Li+ ISE sensors possess a high Nernst slope (59.14 mV/dec), rapid response (<10 s), and superior selectivity against competitive ions (Na+, log Ks = -2.35; K+, log Ks = -2.47; Ca2+, log Ks = -4.05; Mg2+, log Ks = -4.18). The impedance (85.1 kΩ) of (PAH/PSS)5.5-coated sensors is 1 order of magnitude lower than that of electrospray ion-selective membrane (E-ISM) Li+ sensors (830 kΩ), attributed to the ultrathin (45.3 nm) and highly dielectric PAH/PSS bilayers. During a 15-day continuous monitoring test in LrB, the (PAH/PSS)5.5-coated Li+ ISE sensors with their superhydrophilic and smooth surface diminish nucleation sites for scaling agents (e.g., Ca2+ and SO42-) and consequently mitigate gypsum scaling. Moreover, a brine-tailored denoising data processing algorithm (bt-DDPA), coupled with the salinity-adjusted mathematical model with Lagrange interpolation, effectively captures Li+ fluctuation by filtering out anomalies and reducing sensor drift in brine. Bt-DDPA alleviates the discrepancy between the sensor readings and the lab-based validation results by 46.06%. This study demonstrates that the integration of material advancement (PAH/PSS coating) with sensor data processing (bt-DDPA) bolsters continuous and accurate Li+ monitoring in LrB, crucial for brine water treatment and resource recovery.

Electrochemical sensor based on molecularly imprinted polypyrrole-MWCNTs-OH/covalent organic framework for the detection of ofloxacin in water.

Aplatform was developedto accurately detect the content of ofloxacin (OFX) based on molecularly imprinted polypyrrole-MWCNTs-OH/1,3,5-Tris(4-aminophenyl) benzene (TAPB)-2,5-dimethoxybenzene-1,4-dicarboxaldehyde (DMTP)-covalent organic framework (MIP-MWCNTs-OH/COF)-modified glassy carbon electrode (GCE) sensor (MIP-MWCNTs-OH/COF/GCE). The complex of MWCNTs-OH and COF synergistically enhanced the active area and electrochemical signal, based on which a molecularly imprinted membrane was polymerized on its surface to further improve the selectivity. Under optimized conditions, the prepared MIP-MWCNTs-OH/COF/GCE sensor exhibited strong detection performance to OFX in a linear range 1.969 × 10-11-9.619 × 10-9M with the limit of detection (LOD, 3S/N) of 4.989 × 10-12M, excellent selectivity, stability, and reproducibility. Furthermore, the MIP-MWCNTs-OH/COF/GCE sensor can be successfully applied tothe detection of OFX inlake water and eye drops with a relative standard deviation (RSD) of less than 4.95%, indicating its highpotential in practical applications.

Self-powered flexible ultralong electrode sensor made by material-extrusion for artificial intelligence driven accurate motion recognition

Self-powered flexible ultralong electrode sensor made by material-extrusion for artificial intelligence driven accurate motion recognition

РОЗРАХУНОК ПОХИБКИ ЄМНІСНОГО СЕНСОРА ПОВІТРЯНОГО ПРОМІЖКУ В ГІДРОГЕНЕРАТОРАХ З СИСТЕМОЮ КОМПЛАНАРНИХ ЕЛЕКТРОДІВ, ЗУМОВЛЕНОЇ ПЕРЕКОСОМ

In this paper calculating the technological errors that arise when using capacitive sensors to measure the air gap (AG) in hydrogen generators, in particular, those caused by the inaccuracy of their installation on the machine. The results of the analysis of the error caused by the skew of the plane of the sensor electrodes relative to the constructive boring of the stator core are given. It was found that the skew of the electrodes could significantly affect the accuracy of the measurements, which in turn affects the efficiency and reliability of the hydrogen generator. A detailed assessment of the influence of this skew on the measurement results was carried out using a sensor consisting of a system of N coplanar parallel strip electrodes located perpendicular to the core boring. A calculation scheme has been developed for the quantitative assessment of the error, which allows determining the value of the error taking into account analytical dependencies. Numerical methods were used to assess the influence of skew on the accuracy of measurements, and the results were obtained for a sensor designed for a capsule hydrogen generator of the SGK538/160-70M type. Based on the obtained results, practical recommendations have been developed to reduce the impact of skew error on measurement accuracy. Ref. 11, fig. 6.

Flat-Knitted Double-Tube Structure Capacitive Pressure Sensors Integrated into Fingertips of Fully Fashioned Glove Intended for Therapeutic Use.

A therapeutic glove, which enables medical non-professionals to perform physiotherapeutic gripping and holding movements on patients, would significantly improve the healthcare situation in physiotherapy. The glove aims to detect the orthogonal pressure load and provide feedback to the user. The use of textile materials for the glove assures comfort and a good fit for the user. This, in turn, implies a textile realization of the sensor system in order to manufacture both the glove and the sensor system in as few process steps as possible, using only one textile manufacturing technique. The flat knitting technology is an obvious choice here. The aim of the study is to develop a textile capacitive pressure sensor that can be integrated into the fingertips of a glove using flat knitting technology and to evaluate its sensor properties with regard to transmission behavior, hysteresis and drift. It was shown that the proposed method of a flat knitting sensor fabrication is suitable for producing both the sensors and the glove in one single process step. In addition, the implementation of an entire glove with integrated pressure sensors, including the necessary electrical connection of the sensor electrodes via knitted conductive paths in three fingers, was successfully demonstrated.

ZnO-NF/Graphene/Nafion as electrode platform for some pharmaceutical active ingredients sensor and energy storage applications

This paper presents a simultaneous sensor for the detection of paracetamol (PAR)and ibuprofen (IBU). The sensor is based on a ZnO nanoflower/Graphene/Nafion coated glassy carbon electrode (ZnO NF/GR/Nafion/GCE) and a supercapacitor electrode with the same electrode component. The morphological characterisation of the prepared sensor and supercapacitor electrode was conducted via scanning electron microscopy (SEM), structural characterisation by X-ray diffraction spectroscopy, chemical characterisation by Fourier transform infrared spectroscopy (FT-IR) and Raman analysis. The electroactivity and selectivity of the ZnO NF/GR/Nafion sensor platform towards IBU and PAR were simultaneously investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Electrochemical tests of the sensor were conducted in a three-electrode electrochemical system in 0.1 M B-R buffer (pH 4.0). The linear ranges of the ZnO NF/GR/Nafion sensor towards PAR and IBU were determined in the range of 1.0 and 1000.0 μM. The detection limits for PAR and IBU were calculated as 0.28 µM and 0.31 µM, respectively. In real sample analyses, the efficiency of the investigated sensor in different drug formulations was found to respond to PAR and IBU with high recovery (99.05 % and 103.35 %). The supercapacitor electrode was prepared by changing the same electrode component, amounts and ratios of the components. The performance of the supercapacitor electrode was investigated in the potential range from 0 V to 1.2 V in PVA-H2SO4 electrolyte. The supercapacitor electrode demonstrated a specific capacitance of 488.1 F g−1 at a scan rate of 5 mV s−1 and a capacitance value of 405.5 F g−1 at a current density of 7 mA.cm−2. In this study, the ZnO NF/GR/Nafion/GCE hybrid electrode produced is used as both sensor and supercapacitor electrode material and operates in dual mode. The production method is cheap and simple, and no additional modifications are needed in the production of electrode components. In this study, for the first time in the literature, the electrode material with ZnO NF/GR/Nafion/GCE component is used in the analysis of some pharmaceutical active ingredients and in supercapacitor applications.