Sensors and Actuators Reports最新文献

High temporal and spatial resolution electrochemical sensor arrays can greatly benefit various parallel sensing applications. Herein, we provide a simple method for the controlled and scaled fabrication of bipolar nanoelectrode arrays (BPnEAs) for high-resolution electrochemical sensing applications. BPnEAs are prepared on silicon nitride film windows through the dual-beam FIB nanofabrication technique. Coupling a conventional electrochemical redox reaction with a tris (2,20-bipyridyl) ruthenium /2-(dibutylamino)ethanol electrochemiluminescence (ECL) system, which is based on a high-viscosity solvent to reduce molecular diffusion, allows for the reporting of conventional electrochemical redox processes with high spatial and temporal resolution. The use of the BPnEA-ECL sensor is demonstrated on 10 × 10 Pt or C BPnEAs for monitoring the reduction of 0.5 M H₂SO₄. BPnEA-ECL sensors containing different electrode materials (Pt and C) are reported for the first time and are used to monitor the reduction of 0.5 M H₂SO₄, thus revealing the difference in electrocatalytic capacities between Pt and C. Subsequently, we reveal the outstanding capabilities of the BPnEA-ECL system for catalyst screening.

In this paper, we report, for the first time to our knowledge, a new versatile and future proof diagnostic platform for diverse applications and heterogeneous biological targets. This platform relies on a plasmonic-augmented silicon photonic biochip to detect bacteria and protein biomarkers within minutes. To demonstrate the potential of this platform in diverse applications, we demonstrate the detection of two heterogeneous targets, the bacterium Escherichia coli (E. coli) and the molecule C-reactive protein (CRP) using a universal detection method. E. coli is one of the most commonly encountered bacterial pathogens involved in food monitoring, food born infections and water contamination applications, while CRP is a well-established disease severity indicator frequently used in common clinical practice. The biochip used is fully compatible with CMOS semiconductor manufacturing, while it hosts biosensors arrays for any combination of detection assays. Each biosensor exploits a 70 μm long aluminum plasmonic transducer within a silicon nitride waveguide-based Mach–Zehnder Interferometer. Each aluminum surface was silanized and biomodified with specific antibodies. Biosensing experiments revealed that CRP can be detected in diverse sample mediums, and E. coli detection was achieved in buffer at concentrations as low as 10 cells/ml within 13–25 min. The results are in good agreement with preceding numerical simulations. The modular nature of the reported biosensing platform makes it scalable and customizable, allowing nearly any combination of diagnostic tests targeting pathogens and proteins to be integrated on the same biochip for food quality monitoring, environmental monitoring, drug discovery and modern cell therapy manufacturing, or biomedical applications.

The presence of ammonia in exhaled human breath serves as a crucial biomarker for renal diseases. This paper presents a highly sensitive ammonia sensor operable at room temperature, utilizing a Ti/Zr dual metal MOF as its core component, synthesized through a straightforward solvothermal reaction approach. The Ti/Zr-MOF demonstrates excellent responsiveness to ammonia gas, with a detection limit of remarkable sensitivity, reaching as low as 2 ppm. Notably, the sensor exhibits practical insensitivity to similar concentrations of other major interfering breath volatiles, including acetone, ethanol, and saturated moisture. Electron Paramagnetic Resonance (EPR) analysis confirms the presence of oxygen vacancies (Ov) in Ti/Zr-MOF materials, with Ti/Zr-MOF exhibiting stronger Ov signals and the potential for enhanced NH3 adsorption and capture. In-situ FTIR spectrum analysis reveals ammonia-induced -OH (H₂O) moiety formation, indicating a reaction between adsorbed $O_2^{-}$ species and ammonia, resulting in decreased electrical resistance of Ti/Zr-MOF.

Hydrogen peroxide (H₂O₂) sensing has been widely investigated using various electrochemical methods, yet the challenge of finding an imaging technique capable of real-time, spatially resolved detection remains. Addressing this, we introduce a Prussian blue (PB) nanofilm-sensitized plasmonic electrochemical microscopy (PEM) technique that successfully visualizes the localized delivery of H₂O₂. The PB nanofilm was carefully characterized, and its sensing capability towards H₂O₂ was demonstrated in amperometric mode. Employing a precise micromanipulator system, we controlled a micropipette to create a localized concentration gradient on the sensor surface and monitored the gradient through the PB nanofilm-sensitized PEM. The accuracy of the obtained concentration values was further validated by numerical simulations based on finite-element methods. Our technique ensures dependable localized detection, and we anticipate that advancements in film uniformity will further improve the resolution. The potential applications of this technique are broad and significant, including the opportunity to investigate single-cell exocytosis with neurotransmitters like dopamine, thus offering a promising avenue for future biomedical research.

An Aldazine-based optoelectrochemical sensor, BMH (1-(quinolin-4-ylmethylene)hydrazono)methyl)naphthalen-2-ol) has been introduced herein for selective detection of aqueous copper (Cu²⁺) and 2, 4, 6-Trinitrophenol (TNP) at an ultra-low level detection limit (0.09 ppm for Cu²⁺ and 0.019 ppm for TNP). Multichannel recognition aptitude of the chemosensor (BMH) towards both Cu²⁺ and TNP along with bountiful practical applications ascertained it as an innovative one in the environmental and biomedical domains. BMH can detect Cu²⁺ in water, fetal bovine serum, and human urine samples, while explosive TNP can be identified in water, soil, and matches powder. The intracellular Cu²⁺ and TNP recognition efficiencies of BMH have been investigated in human lung cancer cell lines (A459). The hassle-free smartphone ensemble machine learning approach for Cu²⁺quantification has been introduced which would certainly be a significant addition in the domain of water quality analysis. Moreover, the ethylenediaminetetraacetic acid (EDTA) mediated reversibility of the probe could serve as a logic gate imitating electrical circuitry.

The cortisol in human body is a crucial biomarker in terms of wellness management, mental state monitoring and stress-related disorder diagnosis. Therefore, the rapid, reliable and facile measurement of cortisol concentration has attracted extensive research interest. However, traditional cortisol detection such as immunosensing requires demanding laboratory layout, lengthy procedures and high costs, which means, consequently, it is incompatible with the current goal of cortisol sensing. Given the contradiction, an electrochemical sensor based on molecularly imprinted polymer (MIP) for simple, efficient, non-invasive cortisol detection was proposed. The two-step approach employed is simple enough and allows for the mass production of devices. And the embedding of Prussian Blue (PB) within the MIP layer eliminates the need for complex external probes, thereby making the resultant sensors more suitable for integration into wearable devices. We firstly demonstrated the feasibility of the proposed strategy and characterized the successful formation of cavities specific to cortisol molecules. Thereafter, we measured the dependence of the current response on cortisol concentration in Phosphate Buffered Saline (PBS) buffer, which revealed a near-linear relationship between the logarithm of the cortisol concentration and the redox current from 10⁻⁹ mol/L to 10⁻⁵ mol/L, covering the optimal range of cortisol concentration in sweat. Subsequently, sensors with the same specifications were prepared and tested in PBS buffer, exhibiting good consistency. In artificial sweat, we further demonstrated that they have benign selectivity, interference immunity and great potential in practical applications.

Multi-channel neural electrodes as a crucial means are of great significance for information exchange between the brain and computers. Herein, we present a 16-channel Si-based active neural probe system that achieves a monolithic integration between the electrodes and circuits in a single probe, making it a standalone integrated electrophysiology recording system. The ASIC prepared on a base ($2\times 2m{m}^2$) is a 16-channel analog frontend (AFE) for neural recording, and each channel has a low-noise amplifier (LNA), a bandpass filter (BPF), a buffer and a current bias circuit. The 258 neural signal recording electrodes ($22\times 24\mu m^2$) are densely packed on a 50 μm thick, 100 μm wide, and 3 mm long shank. The ASIC of neural probe, internal interconnecting wires are all implemented in commercial SMIC 0.18 μm CMOS technology. The neural probe system achieves a 3.6 μV_rms input-referred noise (IRN) in a bandwidth of 1.1Hz-10 kHz, 70.8 μW power consumption, 0.0785 mm² area per channel, as well as an AFE gain of 58.1 dB Furthermore, the impedances of the Au electrodes can be obtained as 0.5–2.1 MΩ at a frequency of 1 kHz. The functionality of a 16-channel silicon-based neural probe is validated in an in-vivo experiment on lab rats.

We evaluate different methods to detect benzene at a parts-per-billion level regarding their potential to be used in a wearable sensor. Benzene is a carcinogenic molecule, regarded as a major health threat by the World Health Organization. A wearable sensor is necessary to detect leaks immediately, but it is challenging to achieve such low limits of detection and quantification, even with laboratory equipment. A wearable sensor must, in addition to good selectivity and sensitivity, meet stricter requirements of size, weight, temperature, repeatability, and power consumption. We conclude that the most promising techniques for a wearable sensor are either infrared photoacoustic spectroscopy near 14.8 μm, or a photoionization detector combined with one of three selective devices: micro-gas chromatography, cavitands, or catalytic filters (${\text{WO}}_3$, for example). Ultraviolet photoacoustic spectroscopy may also be a suitable future technique for a wearable benzene sensor when efficient LEDs and lasers become available at many UV-C wavelengths.

To practically utilized the organometallic lead halide perovskites to optoelectronic devices and photoelectrochemical cells, numerous efforts have been utilized to obtain the perovskites with low-energy process with coverage of various inorganic mediums to improve stability against humidity. By utilizing ligand-assisted reprecipitation process, under ambient condition at room temperature, the dimensionally confined perovskite quantum dots in silica matrices (PQD@SiO_x) were obtained, and they were stable under several months under the ambient condition. To apply the PQD@SiO_x to the photoelectrochemical cells by introducing direct contact between PQD@SiO_x and electrolyte, the material/photophysical properties under electrochemical conditions are necessary to be studied. However, the role of silica coverage to the electrochemical behaviors of the PQD cores in the silica medium were not yet studied. In this work, under the electrochemical conditions, the oxidative and reductive behaviors of the PQD@SiO_x were studied. Also, through in-situ spectroelectrochemical study, the electrochemically induced irreversible deformation process were tracked. The findings of this study could be used to understand role of silica coverage and develop the strategy to improve the protecting behavior of the silica for the PQD cores to utilize into the photoelectrochemical cells.

For the 29.8 million people in the world living with HIV/AIDS and receiving antiretroviral therapy, it is crucial to monitor their HIV viral loads. To this end, rapid and portable diagnostic tools that can quantify HIV RNA are critically needed. We report herein a rapid and quantitative digital CRISPR-assisted HIV RNA detection assay that has been implemented within a portable smartphone-based device as a potential solution. Specifically, we first developed a fluorescence-based reverse transcription recombinase polymerase amplification (RT-RPA)-CRISPR assay that can efficiently detect HIV RNA at 42 °C. We then implemented this assay within a commercial stamp-sized digital chip, where RNA molecules were quantified as strongly fluorescent digital reaction wells. The isothermal reaction condition and the strong fluorescence in the digital chip simplified the design of thermal and optical modules, allowing us to engineer a palm-size device measuring 70 × 115 × 80 mm and weighing less than 0.6 kg. We also capitalized the smartphone by developing a custom app to control the device, perform the digital assay, and capture fluorescence images throughout the assay using the smartphone's camera. Moreover, we trained and verified a deep learning-based algorithm for analyzing fluorescence images and identifying positive digital reaction wells with high accuracy. Using our smartphone-enabled digital CRISPR device, we successfully detected as low as 75 copies of HIV RNA in just 15 min, showing its potential toward monitoring of HIV viral loads and aiding the global effort to combat the HIV/AIDS epidemic.