Sensors and Actuators Reports最新文献

Fluorescence-activated cell sorting (FACS) holds great promise for the separation of single cells or cell populations according to specific light scattering and fluorescent characteristics. Here, we present a new perspective on microfluidic FACS (μFACS) with predictable geometry, which meets the requirements of high-throughput analysis and sorting. Instead of the widely applied elastic polydimethylsiloxane (PDMS), a rigid epoxy resin chip was rapidly fabricated and irreversibly encapsulated to eliminate channel deformation (tenfold reduction) and enhance performance while meeting high pressure (>600 kPa) and high flow rate application scenarios. Fluorescence discrimination and particle differentiation were additionally validated in a self-contained μFACS system using calibration microspheres and mammalian cells. The μFACS chip and system were integrally optimized to achieve a minimum interval (0.58 ms) with a mean flow rate of 1.5 m/s. Ultimately, event recording and automated sorting were accomplished in real time while achieving a sorting efficiency of 87% at cell throughput of 8,000 events/s. This rigid chip for high-throughput μFACS, which is independent of the physical properties of cells could pave the way for cell screening in plasma samples for personalized medicine.

Efficient and timely detection of cancer biomarkers is pivotal for enhancing treatment outcomes and mitigating patient mortality. This study addresses the pressing need for a swift, accurate, and non-invasive method to identify cancer antigen 125 (CA125), a vital biomarker in ovarian cancer. Leveraging the growing prominence of nano-biosensors for their high selectivity and sensitivity, we present the development and characterization of an innovative electrochemical nano-biosensor. The sensor, featuring aptamer strands immobilized on a glassy carbon electrode modified with graphitic carbon nitrides, molybdenum disulfide, and magnetic nanoparticles (g-C₃N₄/MoS₂/Fe₃O₄), demonstrates superior sensitivity and accuracy in CA125 detection. Utilizing methylene blue for electrochemical detection of labeled CA125 and ferrocyanide for label-free detection, our aptasensor achieves a low limit of detection (LOD) at 0.202 U.mL⁻¹ and 0.215 U.mL⁻¹, respectively, with a broad detection range from 2 to 10 U.mL⁻¹. The modified electrode exhibits a pronounced affinity for CA125, demonstrating enhanced stability compared to other biomolecules. Crucially, the evaluation of both patient and normal serum samples underscores the aptasensor's remarkable performance. These findings not only establish a robust foundation for future research in ovarian cancer diagnosis but also highlight the potential clinical impact of our electrochemical nano-biosensor in advancing early cancer detection methodologies.

The paper describes the development and application of a screen-printed electrode cell with a graphite-ink working electrode modified by a molecularly imprinted electropolymerized polypyrrole for the voltammetric determination of the herbicide 4‑chloro-2-methylphenoxyacetic acid (MCPA). The method exploits the direct measurement of the analyte by applying the differential pulse voltammetry (DPV) technique, taking advantage of the irreversible oxidation peak at about +1.0 V vs. Ag/AgCl pseudo reference electrode. The presence of the molecularly imprinted polypyrrole enhances the sensor's selectivity and sensitivity. A chemometric approach has been crucial for quantitative analysis because of the peak's broad and not well-defined shape. Firstly, a proper pretreatment of the voltammetric signals is identified, proving the most effective is the first-derivative function transformation of the signal. The Partial Least Square regression (PLS) is the tool applied for MCPA quantification. A preliminary PLS model has been developed and validated in dihydrogen phosphate solution at pH 5.5, aiming to optimize the data treatment approach. Then, the same approach is used to develop a PLS model analyzing tap water samples fortified with MCPA and other pesticides as possible interferents to simulate contaminated natural waters. The model correctly predicted the analyte concentration in the range of 2.5–75 μM, assuring the reliability and robustness of the sensor for the possible quantification of MCPA in wastewater samples.

One of the most significant drawbacks of metal oxide (MOS) based chemiresistive gas sensors is the requirement of high operating temperature (250–450 °C), which results in significant power consumption and shorter lifetime. To develop room temperature (21±2 °C) MOS chemiresistive gas sensors, the sensing performance of different MOS nanostructures (i.e., tin (IV) oxide (SnO₂) nanoparticles (NPs), indium (III) oxide (In₂O₃) NPs, zinc oxide (ZnO) NPs, tungsten trioxide (WO₃) NPs, copper oxide (CuO) nanotubes (NTs), and indium tin oxide (In₉₀Sn₁₀O₃ (ITO)) NPs) were systematically investigated toward different toxic industrial chemicals (TICs) (i.e., nitrogen dioxide (NO₂), ammonia (NH₃), hydrogen sulfide (H₂S), carbon monoxide (CO), sulfur dioxide (SO₂) and volatile organic compounds (VOCs) (i.e., acetone (C₃H₆O), toluene (C₆H₅CH₃), ethylbenzene (C₆H₅CH₂CH₃), and p-xylene (C₆H₄(CH₃)₂)) in the presence and absence of 400 nm UV light illumination.

Sensing performance enhancement through photoexcitation is strongly dependent on the target analytes. Under 400 nm UV photoexcitation at 76.0 mW/cm² intensity, room temperature (21±2 °C) NO₂ sensing was readily achieved where SnO₂ NPs exhibited the highest sensor response (S = 474.4 toward 10 ppm_m (parts per million by mass)) with good recovery followed by ZnO NPs > In₂O₃ NPs > ITO NPs. Meanwhile, indirect bandgap n-type WO₃ NPs showed limited NO₂ sensing performance under illumination, whereas p-type CuO NTs showed relatively good sensing response. The most significant improvements in SnO₂ compared to other MOS nanoparticles might be attributed to the highest number of photogeneration electrons, which rapidly reacted with adsorbed $N{O}_2^{-}$ species to enhance the reaction kinetics. WO₃ NPs showed a unique sensing response toward aromatic compounds (e.g., ethylbenzene and p-xylene) under UV illumination, where maximum sensitivity was achieved under 36 mW/cm² irradiation. Changing light intensity from 0.0 to 36.4 mW/cm², WO₃ showed 15.4-fold and 6.3-fold enhancement in sensing response toward 25 ppm_m ethylbenzene and 100 ppm_m p-xylene, respectively. 400 nm optical excitation has a limited effect on the sensing performance toward CO, SO_2, toluene, and acetone.

Nanoplasmonic sensing (NPS) is a comparatively new and powerful technique, which is yet to achieve its full potential across various fields of sciences. The principle behind NPS is localized surface plasmon resonance. NPS has several advantages over traditional sensing techniques when it comes to selectivity, sensitivity, concentration of analyte required, and prohibitive costs involved. The phenomenon exhibits at the resolution depth between two and a few tens of nm, which is difficult in practice or expensive to attain with various modern microscopes. Additionally, NPS is a label free technique which can measure fast and real-time interactions at the solid-liquid interface. This review highlights the applications of NPS in lipid research and the emerging field of extracellular vesicles.

Metal oxide semiconductors infused with noble metals or metalloids are studied and employed in semiconductor sensors applications to a greater extent. In this study, antimony (Sb) is doped with ZnO in 4 different concentrations to compare the optimal parameters in gas sensing properties. Sb/ZnO nanostructure is synthesized by hydrothermal process and deposited on MEMS (Micro electro mechanical system) microheater device. The morphology of the nanostructure is analyzed for planar structure, oxidation states and the presence of Sb/ZnO is successfully verified. Ozone is a powerful oxidizing gas which is a health hazard in public places, so low concentrations of ozone is tested with Sb/ZnO sensor at various parameters. Since Sb acts as catalyst to promote the gas sensing properties, the sensor responses have been enhanced compared to pure ZnO sensor. Sensor performed its best at 200 °C and has the lowest detection gas concentration of 10 ppb. Sb/ZnO showed good selectivity over ozone gas.

A distributed optical fiber system for spectrophotometric analysis of liquid samples based on light diffusing fiber (LDF) is presented. The sensor is based on a high-density white light emitting diode (LED) strip, which is side coupled to a glass based light-diffusing fiber (LDF) that acts as distributed optical receiver. The light emitted from a single LED propagates through the sample medium, is collected by the LDF and is then detected at the end of the fiber by a mini spectrometer. By sequentially turning on one LED at a time, the system permits the spectrophotometric analysis of the sample medium along the entire fiber length. This approach is capable of a continuous monitoring of absorbance spatial profile of liquid sample in the whole visible spectrum with a single low-cost spectrometer. The experimental results confirm the possibility of distributed measurements with a spatial resolution of about 12 mm over 1 m of measurement range. The approach has been successfully employed to the distributed detection and localization of azo dyes in water with a limit of detection lower than 1 ppm.

Per- and polyfluoroalkyl substances (PFAS) are a class of fluorinated pollutants found widely in numerous industrial and consumer products. Their excellent heat, oil, and water resistance and slow degradation rate in nature lead to their persistent environmental accumulation with potential adverse impacts on various organisms, including humans. Although the current EPA-approved PFAS detection method is elegant and ultrasensitive, its broader application is greatly limited due to the associated high costs, lengthy detection times, and skilled personnel requirements. Hence, there is a strong demand for rapid, robust, low-cost, and accessible PFAS detection methods to expedite the treatment of contaminated media and control exposure to these emerging substances. Since the publication of our first PFAS sensing review in 2021, numerous new PFAS sensors have been developed and reported. Consequently, this critical review primarily focuses on recent advancements in PFAS sensing platforms, encompassing optical-based, electrochemical-based, and other novel sensing principle-based systems, as well as those that complement liquid chromatography coupled with tandem mass spectrometry, the gold standard for PFAS detection. The underlying detection mechanisms, sensing performances, and potential areas for improvement are thoroughly discussed. We hope that this article offers readers a review of alternative PFAS detection systems developed in recent years and inspires future innovations in field-deployable PFAS sensing technology.

Impedance assessment in living biological cells has gained popularity as a label-free, real-time, and quantitative analytical approach for determining cellular states. Electric cell substrate impedance sensing (ECIS) provides valuable insights into cell adhesion, the intricate interactions between cells and their underlying substrate, and cellular communication. Further, the ECIS method's high sensitivity enables the observation of biological events at the single-cell level and the precise determination of cell-substrate distances at the nanoscale. Importantly, using cellular electrical properties as a valuable marker, ECIS can shed light on how cancer cells proliferate, migrate, and invade. In this article, we discuss electric cell-substrate impedance sensing as it relates to electrode design, manufacturing, and application in impedance measurement. The present review also outlines our current understanding of the advantages of ECIS in studying cancer cell behavior and drug screening and their prospective future modifications. Impedance-sensing approaches in biology have many potential applications, including point-of-need diagnostics, highly specialized devices, and seamless integration. In summary, this impedance-based technology might one day be an attractive diagnostic tool in cancer research.

In aqueous solution, a non-toxic fluorescent nanosensor incorporating graphene quantum dots encased in molecularly imprinted polymer (GQDs-encased in MIP) is manufactured through a straightforward sol-gel process. During the polymerization process, the functional monomer 3-aminopropyltriethoxysilane (APTES) and the cross-linker tetraethyl orthosilicate (TEOS) were utilized to bind the biotin in a polymer network. The resulting GQDs@MIP nanocomposite outperformed the similar non-imprinted polymer (GQDs-encased in NIP) in terms of biotin selectivity. Under ideal conditions, the produced GQD-encased in MIP are employed to detect biotin by quenching their fluorescence caused by the target analyte via photo induced electron transfer (PET). The quenching curves of each GQDs-encased in polymer were fitted with the Stern-Volmer-type equation, and GQDs-encased in MIP had a broader linear range and a lower limit of detection than GQDs-encased in NIP. GQDs-encased in MIP fluorescence response is linear with respect to biotin concentration over a wide linear range of at least 0.4 μmol L ^{− 1} to 6.7 μmol L ^{− 1}. The detection limit for biotin determination was 315 nmol L ^{− 1}. The suggested GQDs-encased in MIP is promising for the measurement of trace biotin in human serum samples because to its non-toxicity, simplicity, and low cost, as well as its strong analytical performance.