Sensor Material Research Articles

Hydrothermally synthesized CuNiS@CNTs composite electrode material for hybrid supercapacitors and non-enzymatic electrochemical glucose sensor

Hydrothermally synthesized CuNiS@CNTs composite electrode material for hybrid supercapacitors and non-enzymatic electrochemical glucose sensor

CTAB-assisted Hydrothermal Method for Tin Oxide Preparation as an Active Materials for Ethylene Gas Detection

Detection of ethylene gas, a chemical compound that affects the ripening rate of several kinds of fruits, can be one of the solutions to prevent the overripeness of fruits. Metal oxide semiconductors as an active material for gas sensors have several advantages, such as high sensitivity and low cost. Tin oxide is one of the metal oxide semiconductors that is often used to detect several kinds of gases. In this research, tin oxide will be used as an active material for detecting ethylene gas. Tin oxide was successfully synthesized by the CTAB-assisted hydrothermal method and characterized using XRD and SEM. The material is a tetragonal-phase tin oxide based on its diffraction peaks. Meanwhile, SEM imaging shows that tin oxide has morphologies of irregular nanoparticles. The performance test was done by exposing the materials to 20 ppm of ethylene gas in a temperature range of 150°C–350°C. From the test result, it was shown that at higher working temperatures, the sensitivity will be higher. At a working temperature of 350ºC, the sensitivity of ethylene detection is 4.9.

Construction of Conductive Polymer Coatings onto Flexible PDMS Foam Composites with Exceptional Mechanical Robustness for Sensitive Strain Sensing Applications

AbstractFlexible piezoresistive‐sensing materials with high sensitivity and stable sensing signals are highly required to meet the accurate detecting requirement for human motion. Herein, a conductive poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonate) / polydimethylsiloxane foam (P:P@p‐PSF) composite with strong interfacial action is designed. The porous structures and good interface combination not only show outstanding mechanical flexibility and reliability but also possess high sensitivity at a relatively wide strain range. The P:P@p‐PSF sensor achieves extreme sensitivity (Gauge Factor) of 6.25 in the subtle strain range of 1%–8%. Furthermore, the sensor forms a highly interconnected conductive network induced by the serious deformation of elastic‐interconnect pores, thus providing extremely sensitive sensing behavior for a relatively wide strain range (97.4% resistance change rate at 60% compressive strain). Moreover, the sensor presents repeatable stability and good thermal adaptation, which would meet the critical requirements of subtle vital signs, human motion monitoring, and so on. This work supplies insight into the design of a new flexible sensor material to overcome the weak interface problem and the flexible mismatch between conductive filler and matrix, showing great application potential in the field of electronic skin.

Synergism of Holmium Orthovanadate/Phosphorus-Doped Carbon Nitride Nanocomposite: Nonenzymatic Electrochemical Detection of Hydrogen Peroxide.

Developing efficient and robust electrode materials for electrochemical sensors is critical for real-time analysis. In this paper, a hierarchical holmium vanadate/phosphorus-doped graphitic carbon nitride (HoVO4/P-CN) nanocomposite is synthesized and used as an electrode material for electrochemical detection of hydrogen peroxide (H2O2). The HoVO4/P-CN nanocomposite exhibits superior electrocatalytic activity at a peak potential of -0.412 V toward H2O2 reduction in alkaline electrolytes while compared with other reported electrocatalysts. The HoVO4/P-CN electrochemical platform operated under the optimized conditions shows excellent analytical performance for H2O2 detection with a linear concentration range of 0.009-77.4 μM, a high sensitivity of 0.72 μA μM-1 cm-2, and a low detection limit of 3.0 nΜ. Furthermore, the HoVO4/P-CN-modified electrode exhibits high selectivity, remarkable stability, good repeatability, and satisfactory reproducibility in detecting H2O2. Its superior performance can be attributed to a large specific surface area, high conductivity, more active surface sites, unique structure, and synergistic action of HoVO4 and P-CN to benefit enhanced electrochemical activity. The proposed HoVO4/P-CN electrochemical platform is effectively applied to ascertain the quantity of H2O2 in food and biological samples. This work outlines a promising and effectual strategy for the sensitive electrochemical detection of H2O2 in real-world samples.

Synergy of ZnO Nanowire Arrays and Electrospun Membrane Gradient Wrinkles in Piezoresistive Materials for Wide-Sensing Range and High-Sensitivity Flexible Pressure Sensor

Synergy of ZnO Nanowire Arrays and Electrospun Membrane Gradient Wrinkles in Piezoresistive Materials for Wide-Sensing Range and High-Sensitivity Flexible Pressure Sensor

Double crosslinked networks waterborne polyurethane with self-healing, recyclable and antibacterial functions based on dynamic bonds and used for temperature/light sensor

Waterborne polyurethanes with excellent mechanical properties, self-healing under mild controlled conditions and multiple functions are a potential alternative for preparing sensor materials with a wide application prospect. Herein, we introduced dynamic ditelluride bonds and trimethylolpropane into waterborne polyurethane main chains to achieve dynamic polymer chains while maintaining the stability of crosslink networks; subsequently, zinc ions were added to form ionic bonds with carboxyl groups between molecular chains to prepare self-healing waterborne polyurethanes (DTe-WPU-Zn-x) with double crosslinked networks containing double dynamic bonds. The prepared waterborne polyurethane film exhibited excellent mechanical properties (36.08 MPa), satisfactory elongation (665.83 %), and rapid self-healing efficiency (self-healing efficiency with 84.42 % after 90 min of visible-light irradiation). Benefiting from the excellent self-healing efficiency of DTe-WPU-Zn-3, the film fragments can be recycled under ethanol and pressure with lighting for 2 h, and its tensile stress can recover more than 80 % of its original properties after three recycling processes, which is rarely reported for double crosslinked polymers. Furthermore, owing to the combination of telluric radicals and metal ions, the film also has excellent antibacterial properties, with 99.6 % and 96.2 % against E. coli and S. aureus, respectively. Importantly, depending on the stable double crosslinked networks, the prepared sensor has long-term stability and can sensitively monitor changes in human body temperature, and the sensor also has a sensitive light response due to the photodynamic response of ditelluride bonds on polymer chains. In addition, the sensor still has better strain, temperature, and light response after recycling treatment. This research provides a facile method to fabricate environmentally friendly water-dispersible polymers with excellent properties and multiple functions, which have potential applications in the field of smart devices and human–computer interaction.

A DFT study for the detection of CH2O gas by using ZnONTs

In the past few decades, the removal of organic solvents from different substances, especially through the use of nanostructured materials, has been crucial in various industries, including improvement of innovative and adaptable nano adsorbents. Computational approaches are widely recognized as powerful tools for searching molecular systems at atomic level and investigating the characteristics of their interactions. This study utilized the dispersion-corrected DFT approach to gain a detailed comprehension of how CH2O molecules interact with both Pd-doped and pristine ZnO nanotubes (ZnONTs) during the adsorption process. The aim was to achieve a comprehensive comprehension of the adsorption behavior. To accomplish this, an extensive examination of the active sites and optimized geometrical characteristics of interacting systems was conducted. To assess adsorption capacity of Pd-ZnO nanotube and pristine ZnO nanotube for CH2O, binding characteristics of the interacting species have been assessed. This evaluation included analyzing the interaction energy (Eint), charge transfer, electronic properties, and ELF analysis. Moreover, Pd-doping greatly enhances the adsorption strength of ZnONTs, thereby imparting them with superior capability for CH2O adsorption. The significant adsorption strength of CH2O by the sensor under consideration raises the prospect of utilizing these nanotubes as highly effective sensor materials for CH2O detection, which is a matter of great interest. The results of our study provide a foundation for designing innovative and energy-efficient nanosensors that can serve as cost-effective solutions for detecting contaminants in wastewater.

Understanding the photo-sensitive essence of organic-inorganic hybrids for the targeted detection of azithromycin

Being a macrolide antibiotic, the antiviral and anti-inflammatory properties of azithromycin (AZM) were taken advantage of during the COVID-19 pandemic which led to the overuse of AZM resulting in excessive release and accumulation in the waterways and ecosystem causing unpleasant threats to humankind. This demands the necessity for a highly sensitive material being capable of recognizing AZM in wastewater. Mindful of the optical attributes of organic ligand structures, we have constructed a hybrid material by chelating Zn2+ with pyridyl benzimidazole (PBI). The prepared sensor material ZnPBI was characterized using various microscopic and spectroscopic techniques including XRD, FT-IR, HR-SEM, HR-TEM, etc. The proposed sensor material exhibited proficient detection performance selectively towards AZM with a very low detection limit of 72 nM. Two linear ranges between 0 – 70 μM and 70–100 μM were observed corresponding to two different mechanistic pathways. To the best of our knowledge, the utilization of a metal-organic complex (MOC) for the fluorometric detection of AZM has not been explored so far. It is creditworthy to cite that the long-term structural stability of the sensor material was maintained for 100 days in water and it can be reused three times without any depreciation in the sensing activity. A combination of energy transfer routes, adsorption and electrostatic interactions for AZM detection are described experimentally and theoretically which provides insights into the role of MOC as sensing probes.

Investigation of Laser-Induced Graphene (LIG) on a Flexible Substrate and Its Functionalization by Metal Doping for Gas-Sensing Applications.

Graphene materials synthesized using direct laser writing (laser-induced graphene; LIG) make favorable sensor materials because of their large surface area, ease of fabrication, and cost-effectiveness. In particular, LIG decorated with metal nanoparticles (NPs) has been used in various sensors, including chemical sensors and electronic and electrochemical biosensors. However, the effect of metal decoration on LIG sensors remains controversial; hypotheses based on computational simulations do not always match the experimental results, and even the experimental results reported by different researchers have not been consistent. In the present study, we explored the effects of metal decorations on LIG gas sensors, with NO2 and NH3 gases as the representative oxidizing and reducing agents, respectively. To eliminate the unwanted side effects arising from metal salt residues, metal NPs were directly deposited via vacuum evaporation. Although the gas sensitivities of the sensors deteriorate upon metal decoration irrespective of the metal work function, in the case of NO2 gas, they improve upon metal decoration in the case of NH3 exposure. A careful investigation of the chemical structure and morphology of the metal NPs in the LIG sensors shows that the spontaneous oxidation of metal NPs with a low work function changes the behavior of the LIG gas sensors and that the sensors' behaviors under NO2 and NH3 gases follow different principles.

Opportunity and Challenge of Emerging COFs in Chemiresistive Sensing for Gas and Humidity

AbstractNovel 2D materials for chemiresistive sensors are attractive due to their large surface area and structure diversity. Covalent organic frameworks (COFs) have received much attention due to their unique properties, including the abundant choice of organic building units, permanent pore structure and crystallinity, which show huge potential of implement in gas and humidity detection in complex environment. Recently, the development of the synthesis and modification methods for COFs powder and film contributes to the sensitivity and compatibility in chemiresistive sensors and integrated devices. In the present review, the current synthesis methods of COFs powder and film as well as their application in the chemiresistive sensors are summarized. The current challenge and future modification strategy are discussed for the further development of COFs as active materials in gas and humidity sensors.

Development of assessment instruments on limb and sensory materials based on the BATURADEN word wall application for elementary school students

Assessment activities that are often used by teachers are conventional, namely, students doing written questions and students answering on answer sheets provided by the teacher. Conventional assessment has several disadvantages, namely the cost of procuring paper for doubling questions, less effective and efficient proofreading time, and errors when correcting. The purpose of the study was to develop a word wall-based assessment instrument on Body Parts and Senses material for elementary school students. This research is included in development research that modifies the research steps of Borg Gall. The method of data collection is through validation questionnaires filled out by experts using the Likert scale. While the calculation of the validity test uses Aikes's formula. Based on validation tests from material experts, linguists, media experts, and instrument experts, the BATURADEN word wall application-based assessment instrument is valid. Based on reliability tests conducted during small-scale tests, the BATURADEN word wall application-based assessment instrument was declared valid with a value of 0.758 which means it is reliable.

Research Progress in Self‐Powered Pressure Sensors for Internet of Healthcare

AbstractTo mitigate the risks posed by noncommunicable chronic diseases (NCDs) to human health, the Internet of Healthcare (IoH) requires sensors with real‐time and long‐term monitoring capabilities. However, traditional pressure sensors, due to their high‐power consumption and non‐rechargeability, are unbale to meet the increasingly stringent requirements of physiological monitoring devices in the IoH. The emergence of self‐powered pressure sensing technology, exemplified by nanogenerators, provides a new strategy for the next generation of wearable health monitoring devices. This review begins by discussing the merits and drawbacks of different pressure‐sensing modes for healthcare monitoring. Then, it introduces the development and working mechanism of self‐powered triboelectric and piezoelectric sensors. Furthermore, it summarizes the optimizations of sensor structure and material selection aimed at improving sensing performance and achieving high accuracy in sensor networks within the IoH. Relevant application based on independent, or hybrid mechanisms are also covered. Finally, the challenges and prospects for achieving large‐scale commercial applications of self‐power sensing system in IoH are discussed.

Detection of C6H6, CO2, and H2S gases on arsenic (As) and cobalt (Co) doped quantum dots (QDs) nanostructured materials

Abstract Gas sensors exhibit significant potential due to their widespread use in various applications, such as food packaging, indoor air quality assessment, and real-time monitoring of man-made gas emissions to mitigate global warming. The utilization of nanostructured materials for sensor and adsorbent surfaces has seen remarkable growth over time, though substantial efforts are still needed to develop more efficient adsorbents. Consequently, this study investigates the viability of metal-doped quantum dots (QDs) as prospective gas-sensing and adsorption materials. Density functional theory (DFT) calculations employing the 6-311 + G(d,p) basis set and three functionals (B3LYP, B3LYP-GD3(BJ), and ɷB97XD) were utilized for this investigation. Three environmentally and health-significant gases (C6H6, CO2, and H2S) were chosen as adsorbates on arsenic (As) and cobalt (Co) functionalized QDs to assess the performance and sensing capabilities of resulting QD surfaces. The analysis encompassed computation of adsorption energy, thermodynamic properties, non-covalent interactions, natural bond orbital analysis, and other topological aspects for both the surfaces and gases. The outcomes indicate that the GP_As functionalized surface exhibits a lower energy gap, rendering it more reactive and sensitive toward the respective gases (C6H6, CO2, and H2S). Moreover, the calculated adsorption energies of the investigated systems indicate thermodynamic favorability and spontaneity. Notably, our findings suggest that QD_As surfaces possess superior adsorption potential for H2S compared to the other gases examined; nonetheless, all studied QD surfaces demonstrate significant adsorption capacities for C6H6, CO2, and H2S gases.

Recent advances in In2S3-based nanocomposites for gas and electrochemical sensors: Mechanisms and developments

Due to their superior sensing characteristics, In2S3-based nanocomposites have emerged as attractive materials in gas and electrochemical sensors in recent years. This review article gives an in-depth look at the most recent advancements in using In2S3 as a fundamental component in sensor applications. The discussion begins with an overview of In2S3 as a sensor material, including its intrinsic features and gas and electrochemical detection possibilities. The study digs into In2S3′s gas and electrochemical sensing methods, clarifying the processes that underpin its sensitivity to specific analytes. It investigates the interaction of In2S3 with target gases or ions, emphasizing the significance of surface chemistry, charge transfer, and structural alterations in the sensing process. This review paper focuses on recent gas and electrochemical sensing advances made by In2S3-based nanocomposites. Researchers improved sensor performance by integrating In2S3 into diverse composite architectures. It also includes case studies and effective examples of In2S3-based nanocomposites in real-world sensing applications. These examples illustrate the sensors' usefulness and adaptability in detecting a wide range of gases and ions with great sensitivity and selectivity. In summary, this review paper provides an in-depth look at the most recent advancements in In2S3-based nanocomposites for gas and electrochemical sensors. It provides an excellent resource for academics, engineers, and professionals by illuminating sensing mechanisms, stressing essential parameters, highlighting current discoveries, supporting further innovation, and the broader application of In2S3-based nanocomposite sensors.

Preparation of CNTs-HfB2-SiBCN ceramic composite coatings with adjusted electrical conductivity

Aiming at the lack of stable and reliable electrode materials for high temperature wireless sensors, a solution was proposed to use SiBCN ceramic as thin film electrode. To optimize the conductivity of SiBCN coatings, different conductive fillers were incorporated into the precursor solution to prepare conductive SiBCN coatings and the relationship between the coating process parameters, surface morphology and conductivity was established. The results show that the microstructure of the composite can be adjusted in terms of the HfB2/CNT ratio to optimize the electrical conductivity. HfB2 and CNTs are evenly distributed in the coating by adding dispersants and ground SiBCN self-fillers. The electrical conductivity of SiBCN coatings can be greatly enhanced by adding HfB2 and CNTs fillers. Integrating conductive fillers such as HfB2 and CNTs can form a diafiltration path and the resistivity of the prepared coating has been determined to be as low as 0.13 ± 0.01 Ω m. The conductivity did not necessarily increase with an increasing amount of fillers. Adding a balanced amount of filler particles to the ceramic matrix is the requirement for optimizing the electrical conductivity of the coating.

Analysis of the Effect of Copper Doping on the Optoelectronic Properties of Indium Oxide Thin Films and the Thermoelectric Properties of an In2O3/Pt Thermocouple

The detection and real-time monitoring of temperature parameters are important, and indium oxide-based thin film thermocouples can be integrated on the surface of heaters because they operate normally under harsh conditions and provide accurate online temperature monitoring. The higher stability and appropriate optical and electrical properties of In2O3 make it very suitable as an electrode material for thermocouple sensors. This work demonstrates that copper doping can alter the optical and electrical properties of In2O3 films and regulate the output performance of thermocouples. Copper-doped In2O3 thin films were prepared using the magnetron co-sputtering method. The doping concentration of Cu was controlled using direct current (DC) power. An In2O3/Pt thermocouple sensor was prepared, and the optoelectronic and thermocouple properties were adjusted by changing the copper doping content. The thickness valve of the thin film sample was 300 nm. The results of the X-ray diffraction suggested that the structure of the doped In2O3 thin films was cubic. The results of the energy-dispersive X-ray analysis revealed that Cu was doped into the In2O3 thin films. All deposited films were n-type semiconductor materials according to Hall effect testing. The 4.09 at% Cu-doped thin films possessed the highest resistivity (30.2 × 10−3 Ω·cm), a larger carrier concentration (3.72 × 1020 cm−3), and the lowest carrier mobility (0.56 cm2V−1s−1). The optical band gap decreased from 3.76 to 2.71 eV with an increase in the doping concentration, and the transmittance of the film significantly reduced. When the DC power was increased, the variation range of Seebeck coefficient for the In2O3/Pt thermocouple was 152.1–170.5 μV/°C, and the range of thermal output value was 91.4–102.4 mV.

Nanocomposite modified electrode based on polyaniline/Ti3C2 for the simultaneous detection of purine bases and uric acid

In this study, a nanocomposite of Polyaniline/titanium carbide (PANI/Ti3C2) was synthesized through self-assembly and in situ polymerization for use as a sensor material to simultaneously detect guanine (G), adenine (A), and uric acid (UA). X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were utilized to confirm the successful synthesis of PANI/Ti3C2. Electrochemical analysis methods including differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were used to detect the electrochemical performance of PANI/Ti3C2 modified glassy carbon electrode (PANI/Ti3C2/GCE). The pH dependence, electrochemically active surface area (ECSA), electron transport, stability, reproducibility, sensitivity, and selectivity of the modified GCE were examined. Compared to previous reports, the nanocomposite exhibited excellent performance. Uric acid, guanine, and adenine detection limits were 0.33, 0.31, and 0.28 μM, respectively, over concentration ranges of 0.62 - 20.10, 0.31 - 17.00, and 0.31 - 17.00 μM. The nanocomposite demonstrated high recovery and low error in serum sample detection. In summary, PANI/Ti3C2 is a sensor material with excellent electrochemical properties.

Ultrasensitive simultaneous determination of hydroquinone and catechol by Ni3ZnC0.7/Ni porous composites derived from Ni/Zn-MOF

Rational constructing metal–organic frameworks (MOFs) based composite materials with outstanding catalytic capability is vital to accomplish high-performance electrochemical sensors. In this paper, the precursor Ni/Zn-MOF was fabricated by a simple one-step solvothermal method, and then the Ni nanoparticle-supported porous microsphere composites (Ni3ZnC0.7/Ni) were obtained by pyrolysis in N2 atmosphere. The physicochemical characteristics of the as-prepared Ni3ZnC0.7/Ni were studied by XRD, SEM, EDS, TEM, FTIR and XPS, and their electrocatalytic activity were tested by Cyclic voltammetry (CV) and differential pulse voltammetry (DPV). On this basis, an electrochemical sensor strategy for the simultaneous determination of hydroquinone (HQ) and catechol (CC) with Ni3ZnC0.7/Ni modified glassy carbon electrode (GCE) was proposed. In addition, they were applied to the electrochemical simultaneous detection of HQ and CC for the first time. Compared with NiC and ZnC modified electrode, the Ni3ZnC0.7/Ni composites modified electrode can significantly enhance electrocatalytic activity and improve the selectivity and sensitivity of the detection of HQ and CC. The performance was due to increasing the active surface area of the modified electrode and the Ni atom has excellent electrocatalytic capability to dihydroxybenzene. The experimental results exhibits that the composite was used to achieve simultaneous detection of HQ and CC in single-component or two-component solutions with satisfactory result. It has a low limit of detections (LOD = 3σ/k) (HQ: 0.14 μM, CC: 0.21 μM) and a wide detection range (HQ: 0.3–100.0 μM, CC: 0.5–100.0 μM). Meanwhile, the constructed sensor has been successfully employed for determination of HQ and CC in Yellow River water and tap water, and obtains good recovery rate. This work develops a new approach for design and engineering of MOF materials for electrochemical sensors and environmental monitoring.

A Metal-Free Triazacoronene-Based Bimodal VOC Sensor.

Developing suitable sensors for selective and sensitive detection of volatile organic compounds (VOCs) is crucial for monitoring indoor and outdoor air quality. VOCs are very harmful to our health upon inhalation or contact. Bimodal sensor materials with more than one transduction capability (optical and electrical) offer the ability to extract complementary information from the individual analyte, thus improving detection accuracy and performance. The privilege of manipulating the optoelectronic properties of the polycyclic aromatic hydrocarbon-based semiconducting materials offers rapid signal transduction in multimodal sensing applications. A thiophene-functionalized triazacoronene (TTAC) donor-acceptor-donor (D-A-D) type sensor is reported here for VOC sensing. The single-crystal X-ray structure analysis of the TTAC revealed that a distinctive supramolecular polymer architecture was formed because of cooperative π-π and intermolecular D-A interactions and exhibited rapid signal transduction upon exposure to specific VOCs. The TTAC-embedded green luminescent paper-based test strip exhibited an on-off fluorescence response upon nitrobenzene vapor exposure for 120 s. The selective and rapid response is due to the fast photoinduced electron transfer, as is evident from the time-resolved excited-state dynamics and density functional theory studies. The thick-film-based prototype chemiresistive sensor detects harmful VOCs in a custom-made gas sensing system including benzene, toluene, and nitrobenzene. The TTAC sensor rapidly responds (200 s) at relatively low temperatures (180 οC) compared to other reported metal-oxide-based sensors.

Transparent multifunctional cellulose-based conductive hydrogel for wearable strain sensors and arrays

Conductive hydrogels as promising candidate materials for flexible strain sensors have gained considerable attentions. However, it is still a great challenge to construct hydrogel with multifunctional performance via natural polymer. Herein, a novel multifunctional conductive hydrogel based on methylcellulose and cellulose nanocrystal was prepared via a facile and low-cost strategy. Methylcellulose (MC) was introduced to not only guarantee the stability of tannic acid coated cellulose nanocrystal (TA@CNCs) in LiCl solution, but also improve anti-freezing ability. The obtained hydrogel exhibited high transparency (98 % at 800 nm), good stretchability (663.1 %), low temperature tolerance (−23.9 °C), superior conductivity (2.89 S/m) and excellent UV shielding behavior. Flexible strain sensor assembled by the prepared hydrogels can be used to detect human body motions include subtle and large motions, and exhibited good sensitivity and stability over a wide temperature range. Multiple flexible hydrogels can also be assembled into a 3D sensor array to detect the distribution and magnitude of spatial pressure. Therefore, the hydrogels prepared via natural polymers will have broad application prospects in wearable devices, electronic skin and multifunctional sensor components.