Search Results (2,011)

A naive Bayesian classifier (NBC) combined with principal component analysis (PCA) effectively differentiates the dose-dependent effects of certain groups of psychoactive drugs based on their impact on the amplitude–spectral characteristics of electrocorticograms (ECoG) in rats. This approach has been shown to be useful for pharmacological screening of agents with unknown or poorly understood activity. Despite previously obtained optimistic results, classification determination for some drugs was inaccurate, necessitating the search for possible ways to improve the predictive effectiveness of the proposed algorithm. One possible approach would be to use as input quantitative data not only the impact of the psychoactive drugs studied on the amplitude–spectral characteristics of ECoG but also connectivity changes, including the average coherence power of different pairs of leads. The aim of this study was to compare the accuracy of NBC in classifying the pharmacological mechanism of action of agents with well-known mechanisms (test set) using pharmaco-EEG data on changes in the amplitude–spectral characteristics of ECoG, coherence, and the combined use of two data sets. Materials and methods. Experiments were performed on Wistar rats with chronically implanted ECoG electrodes. The training set, relative to which the effects of the pharmacological agents from the test set were classified, were the matrices of effects of 12 pharmacological agents: the NMDA antagonist dizocilpine, the D2/D3 antagonists haloperidol and sulpiride, the M-anticholinergic tropicamide, the H1/5HT2A receptor blocker hydroxyzine, the acetylcholinesterase inhibitor galantamine, the alpha-2 adrenergic agonist dexmedetomidine, the alpha-2 adrenergic antagonist atipamezole, the adenosine receptor blocker caffeine and the GABA-mimetics aminophenylbutyric acid (phenibut), bromdihydrochlorophenylbenzodiazepine (phenazepam) and 5-ethyl-5-phenyl-2,4,6(1H,3H,5H)-pyrimidinetrione. The test set included various drugs with tropism for the targets of the training set drugs: dopamine receptor antagonists chlorpromazine, droperidol, tiapride and raclopride, H1-histamine blockers diphenhydramine and promethazine, 5-HT2-receptor blockers ritanserin and glemenserin, acetylcholinesterase inhibitor ipidacrine, alpha2-adrenergic receptor antagonist yohimbine, alpha2-adrenergic agonists medetomidine and xylazine, GABA-mimetics 5-ethyl-5-(1-methylbutyl)-2,4,6(1H,3H,5H)-pyrimidinetrione and chloral hydrate. The analysis of the ECoG signal included the calculation of 132 amplitude–spectral characteristics and 75 coherence indicators, which, using the PCA, led to new integrative indicators used for further classification of the NBC. Results and discussion. For each drug in the test set, the median similarity probability with a particular group from the training set was calculated, which was used to assess the classification quality. It was found that, when using the amplitude–spectral characteristics of ECoG, the proposed methodological approach allows for the identification of the ECoG effects of several groups of psychoactive drugs, including D2/D3-dopamine, M-cholinergic, H1-histamine, and 5-HT2-serotonin receptor blockers, AChE inhibitors, GABA-mimetics, and alpha-2-adrenergic receptor agonists and antagonists. This approach enabled the correct classification of 18 of 24 groups in the test set. When using changes in coherence indices as the initial data, the classification accuracy also amounted to 18 of 24 groups. When combining the two data sets, the number of correctly identified NBC groups was 20 of 24 groups. When comparing the classification during training (confusion matrix), it was found that coherence data or adding coherence data to the data based on changes in amplitude–spectral characteristics leads to a statistically significant (p < 0.01 in both cases) increase in accuracy. Conclusions. The obtained data demonstrated high accuracy in classifying the pharmacological activity of the test sample drugs using any of the three compared approaches. Despite the lack of statistically significant differences between them, classification based on the combined dataset demonstrated a higher number of “correct” similarities. This allows us to recommend the approach based on combined data of drug effects on amplitude–spectral characteristics and coherence as the most promising for further studies using pharmaco-EEG screening. Full article

Flexible pressure sensors serve as core sensing components for wearable health monitoring systems, electronic skins for soft robots, and flexible human–machine interaction devices. Benefiting from the interfacial electric double-layer polarization effect, iontronic sensing delivers far higher pressure response sensitivity than conventional parallel-plate capacitive sensors, endowing it with distinctive advantages in the detection of weak physiological signals. Nevertheless, current dense ionic thin-film dielectric layers suffer from limited deformation space under compression and poor low-pressure sensing capability. Mainstream high-precision micropillar arrays are fabricated via photolithography, 3D printing, and metal etching molds, which require costly equipment and complicated fabrication procedures, making large-area mass production unfeasible. Random frosted concave-convex microstructures feature disordered dimensions, leading to severe device hysteresis and narrow linear ranges, which fail to achieve ultrahigh sensitivity alongside a wide pressure detection range simultaneously. To address the aforementioned multiple bottlenecks, this paper proposes a low-cost resin template replication process to fabricate TPU-based ionic thin-film dielectric layers with ordered micropillar array microstructures. Combined with inkjet-printed silver conductive PI flexible electrodes, an iontronic flexible pressure sensor with a sandwich layered structure is constructed. Multi-dimensional investigations including microscopic morphology characterization, electromechanical sensing performance calibration, and human wearable application tests are systematically implemented to thoroughly elucidate the synergistic enhancement mechanism of the arrayed micropillars. Test results demonstrate that the effective pressure detection range of the sensor spans 0–1038 kPa, accommodating ultra-low pressures such as pulse signals as well as medium-to-high-pressure loads including joint bending. The sensitivity reaches 23.27 kPa⁻¹ within the low-pressure range of 0–200 kPa and remains stable at 3.52 kPa⁻¹ in the high-pressure range of 200–1038 kPa, with piecewise linear fitting correlation coefficients of 0.93 and 0.96 respectively. Both the response time and recovery time of the device are 40 ms, and the hysteresis error throughout the loading-unloading cycle is merely 2.62%. After 20,000 consecutive cyclic loading-unloading tests, the peak capacitance output only decays by 5.1%, verifying outstanding mechanical fatigue resistance and electrical stability. Validations in multi-scenario applications prove that the sensor can accurately capture human physiological and motion signals including radial artery pulses, laryngeal deformation induced by multi-syllable vocalization, and multi-angle bending of fingers and elbow joints, suitable for home-based health monitoring, quantitative rehabilitation training, flexible tactile interaction and other scenarios. The entire fabrication process eliminates high-precision micro-nano processing equipment such as photolithography systems, plasma etchers and 3D printers; only general chemical raw materials and conventional laboratory instruments are adopted. The reusable templates enable low manufacturing costs and large-area coating forming, offering a novel low-cost technical solution for the engineering implementation and industrialization of high-performance iontronic flexible pressure sensors. Full article

To address the limitations of traditional trench electrode silicon detectors, such as charge collection dead zones and non-uniform electric fields, this paper proposes a novel 3D silicon detector based on an interleaved trench electrode structure. By constructing interleaved N-type and P-type heavily doped trenches on a lightly doped N-type substrate, enhanced uniformity and depth profile optimization of the electric field distribution are achieved. Moreover, 3D numerical simulations based on TCAD demonstrate that the proposed structure provides a uniform, planar-like electric field distribution; reduces low-field regions; and enables fast carrier collection with a low full-depletion voltage. The results provide a theoretical basis and design reference for the development of novel 3D radiation detectors with low depletion voltages, fast charge collection, and favorable radiation response characteristics. Full article

There is an increasing demand for ultrasound imaging technologies, particularly wearable and portable systems, for continuous physiological monitoring applications. Although some recent flexible ultrasound devices have adopted polymer encapsulations, typical rigid transducer designs still include metal housings and costly electrodes, contributing to increased device weight and fabrication cost. To address these limitations, we developed an aluminum-electrode/3D-printed polymer-housing ultrasound transducer (APUT) utilizing a polyvinylidene fluoride piezoelectric film. Compared to a gold-electrode/metal-housing ultrasound transducer, the APUT material costs and total weight were approximately 66% and 86% lower, respectively. Acoustic evaluation revealed a center frequency of 24.5 MHz and a fractional bandwidth of 60.9%, with axial and lateral resolutions of 51 and 152 μm, respectively. Furthermore, during a 3-h pulsed operation test, the APUT exhibited an initial increase in capacitance followed by a relatively stable response, with no progressive surface-temperature increase detected within the accuracy of the measurement method. Finally, successful ex vivo imaging of chicken breast tissue confirms the APUT’s biomedical applicability, highlighting its potential as a wearable, portable, and disposable ultrasound platform. Full article

In femtosecond-laser processing of titania in water, light can induce reduction and oxidation simultaneously. We follow this redox energy partitioning, in this perspective, from colloidal titania synthesis to hot-electron devices. Femtosecond ablation/fragmentation of an aqueous anatase suspension (515 nm, 230 fs, $5\mathsf{\mu }$J, fluence $F\approx 25.5$ J cm${}^{-2}$/pulse at clamped intensity ∼${10}^{13}$ W cm${}^{-2}$) yields surface-reduced, Ti³⁺-rich bluish TiO_2-x, while the same optical breakdown generates reactive oxygen species (ROS), among them H2O2 and HO^. radicals, which compete by re-oxidising Ti³⁺. When the reduced titania is decorated with plasmonic nanoparticles (e.g., Au), an n-type plasmonic photo-electrode is realised: $sp$ hot electrons are injected over the Schottky barrier, while the deep d-band supplies oxidising holes. The oxygen evolution reaction (OER) proceeds in stages at potentials well above the formal $1.23$ V via the two-electron peroxide route (∼$1.77$ V) or, for sufficiently energetic holes, via the one-electron HO^. route (∼$2.7$ V). In a biased cell, H2 evolves on Pt through the adsorbed (H2⁺)_ad intermediate. The same Au/semiconductor physics on silicon enables sub-band-gap hot-electron photo-detection. Energy-level diagrams (flat-band and in-contact) and the $sp$- vs. d-band origin of the injected carriers are discussed. Full article

Flexible pressure sensors featuring high sensitivity, a broad detection range, and excellent stability are pivotal components for high-precision electronic skins and human health monitoring. To circumvent the limitations of existing sensors in maintaining high responsiveness across extensive pressure ranges, herein, a novel flexible capacitive pressure sensor is developed based on a 3D porous ionogel foam composite (IL/EG/PVA@MF) coupled with a planar electrode array. This device leverages the synergistic structural engineering of the 3D hyperelastic melamine foam (MF) skeleton and the pressure-regulated fringe-field distribution and iontronic interfacial polarization of the porous ionogel. Experimental evaluations demonstrate that the sensor achieves a high normalized sensitivity of 62.45 kPa⁻¹ (2–10 kPa) and maintains reliable piecewise linear sensing performance across a broad working range of 0–50 kPa, accompanied by a rapid response time of within 8 ms. Furthermore, the sensor exhibits outstanding performance consistency after 6000 compression-release cycles at 50 kPa, verifying its good mechanical durability. In practical applications, the device can monitor diverse physiological signals with high fidelity, ranging from subtle radial artery pulses to large-scale joint movements and specific coughing patterns, underscoring its broad potential for integrated wearable systems and intelligent healthcare. Full article

Additive manufacturing provides a fabrication route for electrode components with controlled macrostructure; however, printable carbon inks that also incorporate oxygen reduction reaction active precursors remain underdeveloped. Here, XC-72 carbon was combined with selected metal precursors to prepare N–C, Fe–N–C, and Pt-containing carbon ink formulations for direct ink writing. The precursor mixtures were incorporated into a polyurethane-based matrix, pyrolyzed at 900 °C, and characterized using X-ray diffraction, oscillatory rheology, rotating ring-disk electrode measurements, Brunauer–Emmett–Teller surface-area analysis, and scanning electron microscopy. XRD confirmed retention of carbon diffraction features and the formation of metal-containing crystalline phases after pyrolysis. Oscillatory rheology showed storage moduli exceeding loss moduli for the tested formulations, indicating elastic-dominant behavior suitable for shape retention during printing. For the PGM-free formulations, incorporation of nitrogen and iron precursors improved ORR onset potential, half-wave potential, limiting current density, and electron-transfer selectivity relative to the carbon control. BET analysis showed a decrease in accessible surface area after precursor incorporation, consistent with partial pore blocking or structural modification during pyrolysis. These results establish a printable formulation platform for ORR-active carbon-based inks, while future work is required to isolate the effects of printed architecture, pore hierarchy, and durability under fuel-cell operating conditions. Full article

Chitosan has emerged as a multifunctional biopolymer widely exploited in electrochemical sensing due to its unique physicochemical properties, including biocompatibility, film-forming capacity, protonated amino groups, and strong affinity for metal ions and biomolecules. These intrinsic characteristics enable efficient electrode modification, enhanced analyte adsorption, and immobilization of enzymes, nanoparticles, and 2D materials. In recent years, integrating chitosan with conductive nanostructures, such as carbon nanomaterials, metal oxides, metallic nanoparticles, and layered 2D materials, has significantly enhanced sensor performance, providing high sensitivity, selectivity, stability, and low detection limits across a broad range of analytes. This review presents an updated overview of chitosan’s roles in electrochemical sensing, including its functionalization techniques, electron transfer mechanism, and analyte identification. Key applications, such as biomolecule detection, heavy-metal monitoring, environmental pollutant analysis, pharmaceuticals, and emerging wearable sensing platforms, are discussed. Finally, current challenges and future research directions are highlighted to support the development of next-generation chitosan-based electrochemical sensors. Full article

Flexible capacitive humidity sensors are pivotal for next-generation wearable electronics and Internet of Things (IoT) applications. However, conventional devices suffer from severe salt leaching and delamination of hygroscopic sensing materials, alongside poor interfacial adhesion and mechanical fragility of metallic electrodes. Herein, an innovative in situ strategy is reported for constructing LiCl-CH₃COOK/laser-induced graphene (LIG) composite flexible electrodes via single-step laser direct writing. This approach simultaneously patterns three-dimensional (3D) porous LIG interdigitated networks on polyimide substrates and drives deep infiltration of the LiCl-CH₃COOK hygroscopic phase within the graphene pores. The 3D interconnected LIG skeleton not only provides abundant physical anchoring sites and rapid water vapor transport channels but also effectively suppresses the physical loss and leaching of the deliquesced salts through micro-nanoscale spatial confinement, yielding remarkable interfacial stability and cycling lifetime. Benefiting from the synergistic deliquescence of the composite salts, the sensor delivers an exceptional sensitivity of 65,570% (ΔC/C₀), moderate response/recovery times of 75/90 s, and ultralow hysteresis of 0.981%. Furthermore, the streamlined laser-scribing route replaces conventional costly microfabrication sequences, enabling low-cost, high-precision customization. Demonstrations in human respiration monitoring and smart agriculture validate the sensor’s superior reliability and practical applicability, establishing a novel pathway for miniaturized, highly integrated, and robust flexible humidity detection systems. Full article

Protonic ceramic electrochemical cells (PCECs), including protonic ceramic fuel cells, electrolysis cells and reversible cells, have attracted increasing attention as efficient solid-state devices for electricity generation, hydrogen production and chemical conversion at intermediate temperatures. Recent advances in electrolyte thinning, electrode nanostructuring and interface engineering have enabled remarkable device performance, including reversible operation at 500–650 °C, operation below 450 °C, and expanded fuel flexibility toward hydrogen, ammonia and methane-containing feeds. However, the working-state mechanisms governing their performance and durability remain insufficiently understood. In particular, proton incorporation, surface hydration, proton exchange, proton-coupled oxygen reduction/evolution, electrode reconstruction and buried interface degradation are highly dynamic processes that cannot be fully resolved by ex situ or post-mortem characterization. Operando characterization provides a powerful route to bridge this knowledge gap by directly correlating structural, chemical and electrochemical evolution under realistic temperature, steam, gas atmosphere and electrochemical bias. In this review, we summarize recent progress in operando and in situ characterization of PCECs, with emphasis on vibrational spectroscopy, X-ray-based techniques, neutron methods, electron microscopy and electrochemical diagnostics. We discuss how operando DRIFTS and H/D isotope exchange reveal voltage-dependent proton exchange kinetics, how operando Raman captures oxygen-electrode surface reconstruction, how X-ray and neutron methods probe redox chemistry and proton dynamics, and how EIS/DRT analysis links structural changes to reaction resistance. We further highlight current challenges, including limited access to buried interfaces, difficulty in quantifying protonic defects, insufficient multimodal correlation and the lack of standardized operando cell configurations. Finally, we propose future directions based on isotope-resolved spectroscopy, multimodal operando platforms, AI-assisted spectral/impedance analysis and theory-guided interpretation. This review aims to establish a working-state mechanistic framework for rationally designing durable, high-performance PCECs. Full article

The optoelectronic properties of the lead-free perovskite CsSn_0.5Ge_0.5I₃ are investigated by first-principles calculations and numerical simulations using SCAPS-1D. The energy-level alignment between transport layers and the perovskite layer is evaluated, resulting in the establishment of the PCBM/CsSn_0.5Ge_0.5I₃/PEDOT:PSS structure. Key parameters, including bulk defect density, layer thickness, and electrode materials, are optimised, and the effects of resistance, illumination intensity, thermal stability, and carrier generation-recombination rates on device performance are analysed. The optimal device structure FTO/PCBM/CsSn_0.5Ge_0.5I₃/PEDOT:PSS/C achieves a power conversion efficiency (PCE) of 24.50% and a fill factor (FF) of 80.01%. Machine learning (ML) algorithms are applied to predict photovoltaic parameters, with Random Forest (RF) exhibiting the highest accuracy. SHAP analysis identifies absorber layer thickness as the dominant factor influencing efficiency, providing guidance for experimental optimisation. This integrated approach offers a practical pathway for designing high-performance, stable, and environmentally sustainable perovskite solar cells (PSCs). Full article

Real-time pH measurement and regulation of microliter-scale liquid samples are critical for microfluidic biochemical applications. However, traditional magnetic stirring for macroscopic systems is not applicable under such microscale conditions. This work develops an ultrasound-assisted screen-printed electrode (SPE) pH sensor integrated with a 3D-printed ultrasonic reflection cell and piezoelectric excitation unit. Ultrasound-induced acoustic streaming accelerates mass transfer inside microliter-scale samples. Upon acid addition, the ultrasonic-assisted system reaches potentiometric equilibrium far more rapidly than the static non-ultrasonic control. Optimized parameters are 30 s ultrasonic duration and 5 Vpp input amplitude. The sensor shows linearity from pH 3.04 to 4.15 with R² = 0.9919. Phenolphthalein visualization directly confirms ultrasound-enhanced molecular diffusion. Its mass transfer efficiency matches traditional magnetic stirring, and stable fast equilibrium is realized in complex cell culture medium. This acoustofluidic micromixing strategy offers a simple integrated route for pH monitoring and the regulation of micro-volume biological samples. Full article

Glow-discharge plasma (GDP) poling is revisited as an electrode-free method for activating piezoelectricity in poly(vinylidene fluoride) (PVDF) films. Although this method was proposed several decades ago, its effect on the properties of PVDF films has remained poorly understood. In this work, we demonstrate that GDP enables efficient poling of oriented PVDF films without pre-deposited electrodes and investigate the relationship between plasma treatment time, structural evolution, and piezoelectric response. Commercially available 25 μm-thick oriented PVDF films (PolyK) were treated in a DC glow discharge for 15 s to 15 min and characterized using FTIR, DSC, piezoresponse force microscopy, UV–Vis–NIR spectrophotometry, quasi-static d₃₃ measurements and water contact-angle measurements. GDP poling produced a side-averaged piezoelectric coefficient d₃₃ of up to ~25 pC/N within 1–5 min, with local maxima at approximately 1, 2.5, and 5 min. This behavior was accompanied by pronounced changes in the domain structure, including an increase in the ferroelectric domain size from 86 to 552 nm, while the crystallinity and electroactive phase fraction changed only moderately. Plasma treatment also increased the wettability of the plasma-facing surface, reducing the water contact angle from about 85° to 42° within 3 min. At longer treatment times (>5 min), however, the piezoelectric response decreased and the optical transparency deteriorated because of increased haze and turbidity, most likely associated with plasma-induced chemical modification of the surface layers. These results indicate that GDP poling has an effective processing window of 1–5 min. The proposed approach provides a vacuum-compatible and electrode-free route for preparing PVDF films with increased surface wettability for flexible piezoelectric sensors, wearable electronics, and integrated polymer-based devices, because it is compatible with electrode deposition on an already activated polymer surface within a single vacuum cycle. Full article

This study presents and evaluates a system-level optimization of an electrical resistance tomography (ERT) measurement platform based on a ZYNQ-7020 all-programmable system-on-chip (APS-SoC). The design combines deterministic programmable-logic (PL) acquisition, processing-system (PS) configuration and communication scheduling, AXI/DMA data movement, Gigabit Ethernet transmission, and a seventh-order Butterworth excitation filter. FFT-based amplitude extraction and Tikhonov reconstruction remain on the host computer so that the reconstruction algorithm and regularization settings remain identical for the baseline and proposed systems; the present prototype is therefore not claimed as a fully standalone smart sensor. Under the same 16-electrode tap-water testing configuration, the average frame rate increased from 58.23 ± 1.88 FPS to 123.02 ± 1.62 FPS (mean ± sample standard deviation, n = 10), end-to-end latency decreased from 5.2 ms to 2.1 ms, SFDR increased from 68 dB to 95 dB, and SSIM increased from 0.72 to 0.94. In one representative static hardware record at 160 kHz, the calculated amplitude-stability SNR values were 65 dB and 100 dB for the baseline and proposed excitation paths, respectively, while total harmonic distortion decreased from 15.2% to 7.5%. These single-condition signal quality values are descriptive rather than uncertainty-bounded performance specifications. The image-quality differences are attributed primarily to cleaner boundary-voltage measurements with an unchanged reconstruction method, whereas the frame-rate gain reflects the combined PL/PS data path and Gigabit Ethernet upgrade. Full article

Reproducible electrode placement remains a critical, unresolved challenge in wearable ECG systems, where manual electrode attachment introduces inter-session positional error that degrades signal morphology and compromises multi-lead representation. Although the 12-lead clinical ECG system is the gold standard, conventional setups are often bulky, wired, and dependent on operator expertise, limiting their use in prehospital or remote care. Recent advancements in wearable and wireless ECG systems have improved mobility and real-time monitoring, but they typically suffer from limited lead coverage, discomfort, and unstable connectivity. This paper introduces BioShield-12, an anatomically adaptive thermoplastic polyurethane (TPU) shield fabricated using fused deposition modeling (FDM) to improve multi-site electrode placement and 12-lead electrocardiogram (ECG) reconstruction from a single-shield design based on anthropometric data from ten healthy adults (five male, five female; sizing cohort). Mechanical characterization confirmed TPU’s suitability as a compliant wearable substrate, with toughness of 34.4 MJ/m³ and elastic modulus of 79.1 MPa. Feasibility validation against a research-grade reference (BIOPAC MP36) in twenty healthy subjects (n = 20; 10 male, 10 female; mean age 21 ± 4 years) demonstrated consistent signal fidelity (SNR: 17.5–22.5 dB; Pearson r: 0.93–0.98; power-line interference ratio (PLIR): 1.0–3.2 × 10⁻⁵) and confirmed feasibility of 12-lead reconstruction. This work provides proof-of-concept for an additive manufacturing-based conformal electrode interface that eliminates variability in placement without needing individual attachment. Full article