Hydraulic properties such as porosity, water, and claycontentcan be inferred from electrical parameters like permittivity, conductivity,and resistivity. Spectral data enhance this analysis by revealingfeatures such as pore size and clay type in wet particulate media.In liquid samples, electrode polarization is clearly observed, asorientational polarization occurs only at higher frequencies (MHzto sub-GHz). In contrast, particulate media exhibit electrode polarizationartifacts that obscure spatial polarization peaks within the Hz–MHzrange, especially in highly conductive materials like wet clayey soils,making the Cole–Cole model insufficient for distinguishingthese effects. Therefore, a general circuit model using a parallelform of a resistor and a constant phase element configuration moreeffectively separates inherent material polarization from electrodepolarization. The electrode polarization limiting frequency (fEP) correlates with both material conductivityand electrode properties, even with low-polarization electrodes likeAg/AgCl. A novel method is introduced to estimate the effective constantphase element exponent () using the slope of log permittivity vslog frequency. Finally, the chargeability of kaolinite (m = 0.83–0.86), derived from the ratio of critical frequenciesbetween the Cole–Cole and Pelton models, aligns with its fundamentaldefinition: m = (σ∞ –σ0)/σ∞, where σ0 is the DC conductivity and σ∞ isthe high-frequency conductivity.

Diuron, a widely used herbicide, has been banned or heavilyrestrictedin several countries due to its environmental persistence and toxicityto aquatic ecosystems. Its chemical stability allows it to remainin soil and water for extended periods, leading to long-term contaminationand potential leaching into groundwater. This is particularly concerningbecause diuron has been classified as a possible human carcinogenand exposure through contaminated water, food, or occupational contactraises significant safety concerns. Laboratory-based instruments providea robust methodology for the measurement of diuron, but there is anopportunity for electroanalytical based devices to provide an in-the-fieldapproach that is comparable and, in some cases, can provide enhancedsensitivity. The low-cost and portable nature of electrochemical instrumentsallows one-site analysis, removing sample transportation and storagecosts, and reducing the overall measurement time. In this perspective,we summarize recent advances in the measurement of diuron using electroanalyticalmethods, providing insights into the measurement of diuron using varioussensing materials and electrochemical platforms. A wide range of electrodematerials, such as carbon-based nanomaterials, metal nanoparticles,and molecularly imprinted polymers, have been explored to enhancesensitivity and selectivity in the measurement of diuron, and furthermore,we consider the use electrochemiluminescence and additive manufacturing.This overview highlights the role of material properties, electrodesurface modification strategies, and signal amplification to enhancethe electroanalytical detection of diuron, offering insights intocurrent advancements and future directions in electrochemical sensingfor environmental monitoring.

Rapid and ultrasensitive diagnostic tests for COVID-19remain crucial,yet conventional lateral flow antigen kits are limited by their relianceon labeled probes and suboptimal sensitivity at low viral loads. Here,we present a label-free electrochemical antigen test kit (free-EATK)that enables one-step detection of the SARS-CoV-2 N protein withoutthe need for conjugate pads, covalently labeled redox probes, or signalnormalization schemes. The system integrates a nitrocellulose-coatedelectrode, a redox pad preloaded with [Ru­(NH3)6]3+, and a sample inlet. Upon sample application, theimmunocomplex forms directly at the sensing zone, followed by diffusionof the redox mediator toward the electrode surface. Signal generationis achieved through direct anodic square wave voltammetry, offeringsharp oxidation peaks without additional surface modification or multistepprotocols. The method achieves a detection limit of 0.69 pg/mL, withhigh reproducibility (RSD < 10%, n = 10), sensitivityof 91.7%, and specificity of 100% across clinical samples (n = 24). The free-EATK offers a simple, robust, and reproduciblealternative for early stage infectious disease screening, particularlyin settings where conventional labels or complex assay formats areimpractical.

Mutations in the drug-resistant gene ofMycobacteriumtuberculosiscan make it challenging to use drugs inclinical practice. Traditional genetic testing for resistance requirescell culture and susceptibility testing, which take 1–2 weeks.In this study, a DNA-sensitive hydrogel (pHEAA/pMA-DNA) has been developedwith nucleic acid binding ability, water retention capacity, and high-temperatureresistance, allowing it to work normally at 105 °C. Moleculardynamics simulations have been used to obtain the necessary physicochemicalparameters. The DNA-sensitive hydrogel acts as a novel biosensor fordetecting rifampicin- and isoniazid-resistant gene mutations in Mycobacterium tuberculosis. The microarray sensor’sdetection range is between 109 copies/ml and 101 copies/mL, and its stability coefficient of variation (CV) is 2.424%.The study demonstrates that there is no mutual interference in thegel lattice. In addition, experiments on actual nucleic acid samplesreveal accurate detection of bacterial strains and drug-resistantgene mutations. The regression curve conforms to the kinetic characteristicsof nucleic acid amplification, exhibiting a sigmoidal shape. The Four-ParameterLogistic Regression (4PL) equation was employed for fitting, achievingan excellent coefficient of determination (R2 = 0.99791> 0.99). The method enables parallel detection of microarray biosensorsin multidrug-resistant Mycobacterium tuberculosis. The sensors show high efficiency in detecting resistance mutationsites of Mycobacterium tuberculosis to rifampicin and isoniazid, paving the way for researchers to designdifferent probes in in vitro detection fields.