Sensors and Actuators Reports最新文献

In this study, cupric oxide nanowires (CuO NWs) on patterned interdigitated electrodes (PIEs) used as ozone (O₃) gas sensors, were successfully fabricated using thermal oxidation and the microelectromechanical systems (MEMS) technique. After the thermal oxidation process, CuO NWs with different heights and densities were fabricated using a pure copper seed layer with a thickness ranging from 0.5 μm to 2 μm. In this experiment, a low temperature, low concentration, and repeatable CuO NWs gas sensor was fabricated, which can detect O₃ gas at a low concentration of 50 ppb and low temperature of 100°C with a high sensor response (40%). The concentration response of this gas sensor shows an increasing linear trend, with an increase of O₃ concentration in the range of 50 ppb - 300 ppb. Additionally, the results indicated that this CuO NWs gas sensor is more selective for O₃ than CO, CO₂, C₂H₅OH, C₃H₆O, NO₂, or NH₃. While CuO has been less studied in O₃ detection compared with other semiconducting metal oxide materials, CuO NWs show potential applications in gas sensing devices for low-temperature and low-concentration O₃ environmental monitoring.

As the most economically developed area in China, the environmental water quality of Guangdong-Hong Kong-Macao Greater Bay Area has received extensive attention, and the spatial variations of total phosphorus (TP) in the Greater Bay were significant, conventional laboratory analysis is difficult to meet the requirements of TP monitoring due to time and cost consuming, and Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) technology, combined with the self-adaptive partial least squares (SA-PLS) model, was used to determine the TP concentration. The results showed that P-O vibrations were observed in the wavenumber range of 1200–900 cm⁻¹, and prediction models were established by using this range. For the conventional partial least squares (PLS) model, the R², RMSE and RPD were 0.817, 0.022 mg L⁻¹ and 2.335, respectively, while for the SA-PLS model the prediction was improved with the values of 0.965, 0.010 mg L⁻¹, 5.296, respectively, and the SA-PLS mode prediction was satisfied when the TP content in water was more than 0.05 mg L⁻¹. It was found that the TP determination was interfered by sulfate, when the sulfate content was < 100 mg L⁻¹, both SA-PLS and the conventional PLS model could be used for quantitative analysis of TP; when sulfate content was > 100 mg L⁻¹, PLS model could not be used while the SA-PLS model still achieved an excellent prediction. Therefore, FTIR-ATR combined with SA-PLS model can rapidly determine TP in water, providing an alternative strategy for monitoring TP in natural water bodies.

Wearable glucose biosensors (WGBs) face significant challenges due to pH, temperature, and skin pollutants affecting glucose detection accuracy by disrupting D-glucose anomeric equilibrium. Although mutarotase (MUT) has historically addressed these challenges, recent research attention on MUT is limited. This systematic review evaluates the performance of biosensors utilizing MUT for enhanced glucose detection. Comprehensive searches across PubMed, Scopus, and Web of Science identified 1,603 studies, of which 13 met PRISMA standards and were selected. Data were extracted and synthesized using pre-designed forms, with results presented through charts and tables. The reviewed studies did not provide clear data about the influence of MUT on the limit of detection (LOD). However, glucose biosensors incorporating MUT demonstrated sensitivity across a broad linear detection range, potentially eliminating the need for sample dilution in some instances. MUT also ensures a more accurate representation of total glucose levels in a sample, achieving complete glucose recovery (100 %) in 6 s in amperometric experiments and within 3-4 min in colorimetric, luminometric, polarimetric, and spectrophotometric studies. Despite stability concerns in 8 % of the studies, MUT proved effective across various pH (5.0–8.5) and temperature (20—37 ${}^{\circ }$C) ranges. These results highlight the potential of MUT in advancing glucose wearable biosensing technology.

Hepatitis C virus infection constitutes a significant global public health concern. Fluorescence technique (FL) is a promising biosensor, however, many conventional dyes exhibit reduced fluorescence or no emission at high concentrations. To break through this shackle, an ultrasensitive AIE-based (aggregation-induced emission) FL sensing platform was developed for HCV detection by using the FLRNAs-based T7 isothermal transcription amplification RNA diagnosis combined with AIE luminogens (FTAR) strategy. In the FTAR strategy, the T7 transcription amplification process was responsible for the recognition of the target HCV and produced Pepper aptamer, which could form aggregates of nanoparticles with the HBC, an AIEgen, to produce high-intensity FL. The multi-integrated signal amplification strategy led to ultrasensitivity. Moreover, under the optimal experimental conditions, HCV could be assayed in the range of 100aM-100pM. The proposed strategy has been successfully applied in detecting HCV in clinical samples. In summary, this research was the first to utilize aptamer restriction of AIEgens internal rotation to achieve aggregation-induced emission and presented the successful development of a specific, sensitive and rapid FTAR assay for HCV diagnosis. The proposed FTAR platform with facile operation, short analysis time, low-cost as well as excellent quantification ability could provide a promising tool for point-of-care testing (POCT).

High resolution 3D printing emerges as an alternative to microfabrication due to its fine resolution along with one-step manufacturing. Thus, it is broadly used in many fields, such as biological and chemical applications. We introduce such a technique to the design of the optofluidic probe by integrating optics and microfluidics as an ex vivo liquid core fiber photometry. We build the optofluidic probes with various T-shapes and conduct the transmission measurements and the ray tracing simulations, where the results are comparable. Through the transmission and fluorescence measurements, we obtain optimized curl T-shape dimensions of 524 µm wide, ∼50 µm thick, and 350 µm long with longitudinal spaces between them of 260 um. Furthermore, a heightened level of complexity in structure, characterized by a feature size of 25 µm, is attained through the improvement process. We conclude the feasibility of this optofluidic system with two applications: the in vivo-like setting consisting of thyroid biopsy training phantom and human plasma and the ex vivo-like setting consisting of the mice brain slices stained with wheat germ agglutinin (WGA). This prototype is an important step of establishing a 3D printing optofluidic applications for various in vivo research.

Nanopores play essential roles in biological processes, such as ion channels and pumps in cellular membranes, and in technological applications such as DNA sequencing. Advancements in nanofabrication techniques have enabled the routine integration of nanopores into solid-state devices, resulting in a plethora of analytical applications. This review explores recent developments in nanopore-enabled electrochemical systems, which have transcended traditional resistive pulse sensing to offer novel capabilities in single-entity studies, stimulus-responsive gating, and point-of-care diagnostics. We highlight recent studies on the design and utility of nanopore electrode arrays, which serve as nanocontainers capable of isolating and analyzing single entities, and extend the discussion to hierarchically organized, stimulus-responsive systems that regulate species transport across nanopores, enriching analytes for ultrasensitive detection. In addition, we review the utilization of probe-assisted nanopore sensing, demonstrating its efficacy in selectively binding and detecting target molecules and ions. Finally, we outline future directions for nanopore-based systems to enhance robustness, achieve high-throughput analysis, and incorporate artificial intelligence for materials design and data analysis, promising transformative impacts on diagnostics and biological research.

This study evaluates the influence of paper substrate selection on the electrochemical response of an electrochemical paper-based analytical device (ePAD). Various paper substrates commonly employed in this type of devices such as cellulose, nitrocellulose and glass-fibre based medical grade materials are evaluated using chronoamperometric measurements. Both theoretical modelling and experimental analyses are conducted to understand the diffusion behaviour of widely employed two redox probes, [Fe(CN)₆]³⁻ and FcMeOH. Findings show that glass fibre substrates show similar performance to liquid drop conditions while nitrocellulose cause a decrease in current after a short measurement period, mainly due to a thin-layer effect. Cellulose-based substrates decrease the diffusivity of redox species, especially for charged species, indicating potential limitations in their use for chronoamperometric measurements. The study offers valuable insights into the electrochemical behaviour of paper substrates in ePADs, laying the groundwork for future research in this area.

This work presents the design and optimization of a new Cr(VI)-selective electrode. The new sensor is based on modifying a glassy carbon electrode with carbon quantum dots, ß-cyclodextrin, and carbon disulfide. The carbon quantum dots aided the electrical properties of the glassy carbon by improving charge transfer; the electropolymerization of ß-cyclodextrin resulted in a polymeric membrane that functions as a recognition element when modified by adding sulfur donor groups to its structure. Modifying the membrane with sulfur atoms gave the sensor excellent selectivity toward Cr(VI) ions. The electrode synthesis was optimized using a 2³ factorial design; the factors studied were pH, the number of cycles in the electropolymerization, and the presence or absence of carbon nanoparticles. Eight different electrodes were constructed, and their potentiometric response to different concentrations of Cr(VI) was evaluated for all of them. The analysis of variance of the experimental design found no significant effect of any factor on the response. However, it suggests a strong interaction between the three factors studied. The sensor that presented the best analytical parameters was synthesized at pH 5 and 50 consecutive cycles in the presence of carbon quantum dots. This new electrode, with its response times of 40 s at different concentrations of the metal ion, exhibiting a slope of (66.0 ± 2.1) mV decade⁻¹ and a detection limit of (5.2 ± 0.1)x10⁻⁷ mol L⁻¹, can be used at pH between 0 and 3 without the effect of hydronium ions. The proposed electrode has good reproducibility and excellent selectivity against various metal ions and has significant advantages over other analysis methods. Its cost, ease of construction, easy handling, ease of operation, ease of storage and transportation, as well as good performance, short response time, and high selectivity make this electrode a valuable tool for easy, fast, and reliable monitoring of Cr(VI) in water samples, contributing to the safety and health of our environment.

In the development of biosensors, it is essential to have sensors that provide rapid responses, exhibit high sensitivity and selectivity, and are non-invasive, such as screen-printed carbon electrode-based biosensors. In this study, SPCE-based and fabric-based biosensors were fabricated by modifying the working electrode (WE) surface using functionalized Multi-walled Carbon Nanotube/AgNi nanocomposites (f-MWCNT/AgNi) to enhance the biosensor's performance in detecting uric acid (UA). The successful synthesis of the f-MWCNT/AgNi nanomaterial was confirmed through UV–Vis, Raman, SEM–EDX, and XRD analyses. The f-MWCNT/AgNi nanomaterials were deposited on the WE surface using drop-casting. Subsequently, electrochemical characteristic tests and UA detection performance were conducted using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The DPV curves revealed sensitivities of 27.699 μA/mM and 4.638 μA/mM for SPCE-based and fabric-based electrodes, respectively. The limit of detection (LOD) values for UA detection were 0.024 and 0.017 mM, with linearity (R²) 0.997 and 0.999 observed within the linear ranges of 0.05–1.00 and 1.0–5.0 mM, respectively. Both biosensors exhibited strong selectivity for UA against other components, including ascorbic acid, glucose, lactic acid, and ethanol. Based on these parameter values, f-MWCNT/AgNi-modified SPCE and fabric-based electrodes can be promoted as biosensors for uric acid detection.

Exhausting carbon-based gases from building construction or comfortable household supplies have caused the main pollution gas species for the indoor air environment. Given the variety of indoor activities, many reports have been challenged to find room-temperature operational and harmless materials. Here, we report that the activating MoO vibration mode in Na,Sb doped-NiMoO₄ micro-sized powder reveals the high response of CO and VOC, occupying multiple bonds at room temperature. We performed Na and Sb doping in the α-NiMoO₄ crystal structure, such as introducing the Sb in Ni and interstitial doping of Na in around 4 Å of free space in the NiMoO₄ crystal structure that manipulates the partial β-NiMoO₄ phase. The Na,Sb-codoped NiMoO₄ generates the higher MoO vibration mode from FT-IR measurement and enables carbon-based gas detection with 38 responses to CO and nearly 20 responses to VOC under 20 ppm of each analyte gases environment. Furthermore, the n-type gas sensing behavior of Na,Sb doped-NiMoO₄ chemiresistor exhibits an immediate sensing response instead of a none-of response than intrinsic or single element doped NiMoO₄. These results suggest that Na,Sb codoped-NiMoO₄ is the applicable material for emergent warning against carbon-based gas exposure in the indoor environment. In addition, activating the electrochemical reaction site of MoO₄^–2 in NiMoO₄ is tailorable by a simple doping process.