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Oxygen Saturation Measurements from Green and Orange Illuminations of Multi-Wavelength Optoelectronic Patch Sensors
摘要： Photoplethysmography (PPG) based pulse oximetry devices normally use red and infrared illuminations to obtain oxygen saturation (SpO2) readings. In addition, the presence of motion artefacts severely restricts the utility of pulse oximetry physiological measurements. In the current study, a combination of green and orange illuminations from a multi-wavelength optoelectronic patch sensor (mOEPS) was investigated in order to improve robustness to subjects’ movements in the extraction of SpO2 measurement. The experimental protocol with 31 healthy subjects was divided into two sub-protocols, and was designed to determine SpO2 measurement. The datasets for the first sub-protocol were collected from 15 subjects at rest, with the subjects free to move their hands. The datasets for the second sub-protocol with 16 subjects were collected during cycling and walking exercises. The results showed good agreement with SpO2 measurements (r = 0.98) in both sub-protocols. The outcomes promise a robust and cost-effective approach of physiological monitoring with the prospect of providing health monitoring that does not restrict user physical movements.
关键词： green and orange illuminations,optoelectronic patch sensor (mOEPS),oxygen saturation (SpO2),physical movement,pulse oximetry
更新于2025-09-23 15:23:52
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Detection of divalent copper with improved accuracy by dual suppression of electrochemiluminescent recovery
摘要： This work is to construct an electrochemiluminescent (ECL) sensor with improved accuracy for the detection of Cu2+. The improved accuracy is achieved by utilizing a reaction system to realize Cu2+ dose-dependent dual suppression of ECL recovery from gold nanoparticle-graphitic carbon nitride nanosheet nanohybrid (Au-CNNS) film. The ECL sensor shows sensitive response to Cu2+ in the concentration range of 5 nM to 500 nM with an enlarged slope, and high specificity attributed to the high affinity of CNNS-Cu2+ complex and the high catalytic activity of Cu(NH3)6 2+ to decompose H2O2 in the reaction system. The proposed ECL sensor with improved accuracy may prove valuable in future biomedical applications.
关键词： dual suppression,electrochemiluminescent sensor,copper,graphitic carbon nitride nanosheets
更新于2025-09-23 15:23:52
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Cuprous oxide nanocubes decorated reduced graphene oxide nanosheets embedded in chitosan matrix: A versatile electrode material for stable supercapacitor and sensing applications
摘要： Herein, we report cuprous oxide nanocubes decorated reduced graphene oxide (CNC-rGO) immersed in chitosan matrix as a versatile and enhanced electrochemically active electrode material for both supercapacitor and hydrogen peroxide (H2O2) sensor applications. The CNC-rGO was synthesized by one-pot scalable chemical precipitation method. The morphology and crystal structure of as-synthesized hybrid material was characterized by field emission scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The CNC-rGO hybrid material immersed in the chitosan matrix was used as an enhanced electrochemically active electrode material for supercapacitor and hydrogen peroxide (H2O2) sensor. The fabricated CNC-rGO hybrid in chitosan matrix as an electrode showed remarkable charge storage capacity of 772.3 F g-1 (12.87 mA h g-1) at a current density of 0.2 A g-1 with high cyclic stability over 2000 charge-discharge cycles. Similarly, H2O2 sensing performance of the same electrode exhibits very high sensitivity of 0.33 A M-1 cm-2 within a linear range of detection of 20-160 μM. Thus, the synthesized CNC-rGO hybrid material composed of numerous cuprous nanocubes on rGO nanosheets with large active sites showed enhanced electrochemical activity beneficial towards the supercapacitor and H2O2 sensor applications.
关键词： copper oxide nanocubes,chitosan,supercapacitor,H2O2 sensor,reduced graphene oxide
更新于2025-09-23 15:23:52
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Controlling self-assembling and color-transition of polydiacetylene/zinc(II) ion/zinc oxide nanocomposites by varying pH: Effects of surface charge and head group dissociation
摘要： Polydiacetylene/zinc(II) ion/zinc oxide (PDA/Zn2+/ZnO) nanocomposite exhibits reversible thermochromism and dual colorimetric response to acid/base. This contribution presents our ongoing development of the PDA/Zn2+/ZnO nanocomposite for sensing applications by controlling ZnO surface charge and dissociation of PDA headgroup via pH adjustment. At pH >10, negative ZnO surface charge and PDA carboxylate headgroup significantly enhance molecular organization during the self-assembling process. An increase of the nanocomposite amount after photopolymerization is observed. Oppositely, pH <6 results in irreversible-thermochromic nanocomposites. Additionally, the nanocomposites prepared at different pH change color at different concentrations of chemical stimuli. Molecular packing, local interactions and PDA conformation are investigated.
关键词： self-assembling,color transition,sensor,polydiacetylene,dissociation,surface charge
更新于2025-09-23 15:23:52
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Resistive room temperature LPG sensor based on a graphene/CdO nanocomposite
摘要： The authors decribe an ultra-sensitive, room temperature, flexible transparent LPG sensor based on the use of a CdO/graphene nanocomposite. The graphene prevents the accumulation of CdO, enhances the surface area, and acts as a gas sensing material. FESEM images show a uniform decoration of CdO nanoparticles on graphene. The CdO/graphene composite was deposited as a film on interdigitated electrodes (IDEs) which then were used for chemiresistive sensing of liquid petroleum gas (LPG) by using a four probe technique. A Resistivity decreases significantly upon exposure to a LPG. The electrical resistance measurement at a constant bias voltage of 0.5 V. The sensor of type CdO/graphene (1 wt.%) exhibits a sensitivity of 600 ppm of LPG at 27 °C. It is a highly selective, stable and sensitive to low concentration of LPG even at room temperature.
关键词： Gas sensor,CdO,Liquefied petroleum gas,Graphene,Flexible
更新于2025-09-23 15:23:52
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Selective “Turn-On” Fluorescent Sensor for Cyanide in Aqueous Environment and Test Strips
摘要： A new very sensitive and selective fluorescent phenothiazine probe for the recognition of cyanide ions in an aqueous environment was prepared. The detection mechanism depends on the nucleophilic addition of cyanide ions to the fluorescent probe to result in fluorescent change go together with color change from purple to yellow. The prepared phenothiazine sensor was employed for invention of test strips able to recognize cyanide in aqueous media. It was found that the phenothiazine probe could selectively detect cyanide ions. When adding cyanide anions, the color of the yellow phenothiazine solution in dichloromethane changed to yellowish green, while a stronger green emission was monitored under UV lamp. Furthermore, the existence of 10 equivalents of other anions, including AcO?, HSO4?, Cl?, Br?, I?, H2PO4?, did not result in apparent variations in the UV-Vis absorption and fluorescent emission spectra. The recognition limit of phenothiazine probe to cyanide aions was 7.2 × 10?8 mol/L in dichloromethane.
关键词： Cyanide,Fluorescence,Sensor,Nucleophile
更新于2025-09-23 15:23:52
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Optical measurements based on practical methods for detecting time-wise morphing structures
摘要： Nowadays non-contact measurement methods have become widely used systems in several fields especially robotics, aerospace, architecture, and cultural heritage. Practical devices, taken from mass markets, are increasingly being used in scientific and engineering research fields thanks to their ability to combine good accuracy with to the low-cost and ready-to-use experimental setup. In the present paper, digital image analysis (based on digital camera devices) and three-dimensional scanning technique (based on Kinect I and Kinect II sensors) are compared to evaluate their performance in detecting a time-wise shape modification. Digital camera and Kinect sensors are used to the non-contact detection of a morphing blade able to modify its geometry according to airflow temperature variation. The comparison showed the capability of the digital image technique to provide quantitative information when a proper alignment is adopted, while the three-dimensional scanning process allows the continuous blade detection useful to quantify the shape modification. Two-dimensional and three-dimensional blade shape reconstruction processes are also discussed.
关键词： Reverse Engineering,Non-contact measurement,Point cloud,Kinect sensor,Optical method,Digital image analysis
更新于2025-09-23 15:23:52
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Imitational modeling of synchronous measuring detector with increased noise immunity and precision
摘要： In this paper, an example of application, simulation results, noise and precision properties of a synchronous measuring detector with increased noise immunity and precision (not less than 1%) for the operation providing of primary sensors – thermal sensors and bridge sensors, in particular Hall sensors for magnetic field measurements are considered. As a result of the research, it was discovered that increasing the sensitivity of magnetometers based on Hall sensors leads to the allocation of the initial useful signal of the ultra-low level against the background of noise comparable with it. To allocate the output signal of the Hall sensor or thermal sensor in the background of noise, it is proposed to feed it with harmonic current with the further allocation of the information signal using a in-phase detector with a narrowband low-pass filter.
关键词： sensor,detector,precision,noise immunity,modeling
更新于2025-09-23 15:23:52
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Organic Transistor Based on Cyclopentadithiophene-Benzothiadiazole Donor-Acceptor Copolymer for the Detection and Discrimination between Multiple Structural Isomers
摘要： Distinguishing structural isomers is a critical and challenging task for biotechnology, chemical industry, and environmental monitoring. Approaches currently available are limited in terms of selectivity and simplicity. In this paper, a highly sensitive organic field-effect transistor (OFET) using the cyclopentadithiophene-benzothiadiazole (CDT-BTZ) copolymers as a semiconductor is presented for easy and selective detection of different families of structural isomers, as well as between different isomers within each family. High accuracy discrimination is achieved over a range of concentrations using only a single sensing parameter derived from the OFET characteristic transfer curve. As a reference, other homopolymer- and donor–acceptor copolymer-based OFET sensors are examined but do not have an equivalent sensing performance to that of the CDT-BTZ-based OFETs. Investigating the link between isomer absorption and swelling, supramolecular order and energy levels of the active layer reveals a unique effect of each isomer on the energy bands of the semiconducting polymer.
关键词： isomers,donor–acceptor copolymers,gas sensor,organic field-effect transistor,xylenes
更新于2025-09-23 15:23:52
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Ab Initio Design of Graphene Block Enables Ultrasensitivity, Multimeter-Like Range Switchable Pressure Sensor
摘要： In pursuit of the next-generation pressure sensors, the fabrication of graphene-based devices is considered to be one of the most promising approaches to address the unsatisfied sensitivity within a wide pressure range. Here, an ab initio design based on the graphene block is proposed to realize a high-performance and multimeter-like range switchable pressure sensor. The sensor contains three designed graphene-based foams with different initial resistances, which enable continuous resistance-change behavior induced by the pressure. Specifically, the reduced graphene oxide (rGO) foam–based sensor demonstrates a three times resistance change within the pressure range of 0–300 Pa, the rGO/polyurethane (rGO/PU) foam–based sensor presents a six times resistance change within the pressure range of 0.09–30 kPa, and the selenium-functionalized rGO/PU (SFrGO/PU) foam–based sensor displays a resistance change of more than 1000-fold within the pressure range of 1–72 kPa. Such different initial resistances and responses endow the device with controllable estimating pressure ranges, offering a switchable multimeter-like function for various applications. This ab initio design, which is applicable to various 2D materials and operation modes, can provide a facile and feasible approach toward the next-generation pressure sensors and other application fields related to 2D materials.
关键词： ultrahigh sensitivity,pressure sensor,graphene block,ab initio design,multimeter-like
更新于2025-09-23 15:23:52