Sensor Material Research Articles

Hierarchical porous spindle-shaped MIL-88B@Fe2O3 with core-shelled structure for conductometric trimethylamine detection

Hierarchical porous spindle-shaped MIL-88B (HPS-MIL-88B) with core-shelled structure was prepared by citric acid-assisted. The material exhibits open channels on its outer surface and a hierarchical internal cavity structure with meso-/macro-pores. The samples were then pretreated at 200 °C to form an oxide film, aiming to improve the conductivity of material. The as-prepared HPS-MIL-88B-6 h@Fe2O3 material with core-shelled structure exhibits superior selectivity and high sensitivity to trimethylamine (TMA) at 200 °C (detection limit as low as 1 ppm) with fast response and excellent repeatability. The outstanding sensing performance was owing to the open and hierarchical porous that enhances the reaction between the target gas and the active sites of the material. In addition, the metal unsaturated active sites of MIL-88B (Lewis’s acid) can selectively undergo acid-base reactions with TMA (Lewis’s base), enhancing the generation of oxygen species and improving the selective adsorption capacity towards the target gas. This work provides a new path route for the application of MOF materials in sensors.

Investigation of a sensitive, selective and cost-effective electrochemical meso-porous silicon based gas sensor for NO2 detection at room temperature

This work presents a nitrogen dioxide (NO2) gas sensor based on porous silicon with improved sensitivity, selectivity, and cost-efficiency. Porous silicon is being researched as an alternative material for gas sensors operating at room temperature (RT), making it suited for low-consumption applications. Meso-porous silicon (meso-PS) films were prepared on p+ type Si (100) using an electrochemical method for NO2 gas sensing. Morphology, structural and optical properties of meso-PS films were investigated using scanning electron microscope (SEM), X-ray diffractometer (XRD), and UV-Vis spectroscopy. The gas sensing response of meso-PS samples was performed at RT with top parallel Al electrodes in the range of 4 to 10 ppm of NO2 gas. The tested sensor showed high normalized response (Rair/Rgas =40 for 4 ppm to 100 for 10 ppm) thanks to its high surface/volume ratio, good repeatability and reversibility, fast response (40 s) and recovery times (18 s), and good selectivity for NO2 vs. NH3, O3 and CO. All these performances obtained at RT are encouraging for low-power devices.

Advanced Applications of Porous Materials in Triboelectric Nanogenerator Self-Powered Sensors.

Porous materials possess advantages such as rich pore structures, a large surface area, low relative density, high specific strength, and good breathability. They have broad prospects in the development of a high-performance Triboelectric Nanogenerator (TENG) and self-powered sensing fields. This paper elaborates on the structural forms and construction methods of porous materials in existing TENG, including aerogels, foam sponges, electrospinning, 3D printing, and fabric structures. The research progress of porous materials in improving TENG performance is systematically summarized, with a focus on discussing design strategies of porous structures to enhance the TENG mechanical performance, frictional electrical performance, and environmental tolerance. The current applications of porous-material-based TENG in self-powered sensing such as pressure sensing, health monitoring, and human-machine interactions are introduced, and future development directions and challenges are discussed.

Structural, electrical and magnetoresistance feature of PP+Fe3O4 + Multi-walled carbon nanotubes nano-hybrid based polymer nanocomposite

This work studied the role of the iron oxide and MWCNT in a change of the electrophysical properties of PP + Fe3O4 + MWCNT nanocomposite to evaluate the potential of these nanocomposites as magnetic field sensors and EMI materials. The morphology of the obtained nanocomposites was studied with a scanning electron microscope and investigated that the sizes of both magnetite nanoparticles and carbon nanotubes stay stable during the three-phase nanocomposite formation. In addition, the X-ray diffraction method revealed that MWCNT plays an essential role in the ordered structure-formation of a polymer nanocomposite more than iron oxide nanoparticles. Dielectric properties of the PP + Fe3O4 nanocomposite were studied. Both dielectric permeability and dielectric losses of PP+MWCNT+Fe3O4 nanocomposites were enhanced. The dielectric permeability of the nanocomposite increased due to the interphase polarization, which in turn related to the formation of ordered structure caused the partial arrangement of carbon nanotubes in the polymer. Furthermore, the study showed that the negative magnetoresistance effect of PP+MWCNT+Fe3O4 nanocomposites is more dependent on the amount of Fe3O4 nanoparticles than that of MWCNT, which explained by the spin polarization of Fe3O4 nanoparticles at room temperature. In this research, the PP+5%Fe3O4+1%MWCNT nanocomposites were considered to be an effective material for magnetic field sensors and EMI shielding.

Engineering luminescent quantum dots through laser ablation of samarium oxide (Sm2O3): A novel approach for enhanced fiber optic gas sensing

Underexplored Sm2O3, with tunable redox and high-surface nanostructures, emerges as a promising volatile organic compounds (VOCs) sensor material for next-gen applications. This study presents the successful synthesis of novel Sm2O3 luminescent quantum dots using a unique pulsed laser ablation technique. Material characterization by FESEM, XRD, EDAX, and HRTEM confirmed the formation of cubic polycrystalline quantum dots. The optical properties were studied by UV-Vis absorption and PL spectroscopy. These quantum dots were then employed in clad-modified fiber optic gas sensors operating at room temperature. Sensor response towards various VOCs, including acetone, ethanol, methanol, and ammonia, were evaluated. Ethanol displayed remarkable sensitivity and selectivity among the other, with a response of 104 ×103 Counts/kPa at 25 °C for 500 ppm. Rapid response and recovery times of 48 and 55 seconds, respectively, further highlights the sensor’s performance. These results establish Sm2O3 quantum dots as a promising and highly effective material for ethanol sensing.

Nanoclay biosensor for rapidly detecting lung cancer biomarkers at room temperature: A first principles study

The detection of volatile organic compounds (VOCs) in exhaled gas is crucial for noninvasive diagnostic applications in lung cancer. Herein, we systematically employed first-principle calculations to investigate the utilization of nanoclay as a sensing material for the development of sensitive biosensors for VOCs. In this study, the effect of VOCs adsorption on the structural and electronic properties of pristine kaolinite (Kaol) and transition metal [TM(II/III)] doped kaolinite [TM(II/III)-Kaol, TM = Fe, Co, and Ni] was investigated. The calculation results show that TM doping induces a slight structural perturbation, and VOCs lead to a decrease in the bandgap of pristine TM(II/III)-Kaol. Additionally, we have comprehensively discussed that the adsorption of VOCs causes significant changes in the electronic behavior of TM(II/III)-Kaol, including density of states, charge transfer, molecular front orbitals, and work functions. In particular, we also have calculated the recovery time to determine the reusability of the designed sensor material. Our results specifically support the fact that TM(II/III)-Kaol can be an attractive sensing material for VOCs biosensors.

Designing a heavy metal electrochemical sensor for Pb detection in water—A generalized approach for electrochemical sensing using low‐cost materials

AbstractThis work attempts to design an elemental method for detecting heavy metals in water. The presence of heavy metals in water is a critical issue that needs a check at every level of water consumption. To facilitate the checking, a simple method needs to be identified and developed. Electrochemical sensing is essentially a surface phenomenon and requires a higher surface area for greater accuracy and reliability. We have attempted to use a readily available Cu wire for detecting Pb to 50 μM concentration with 90% reliability. It is important to note that the sensing electrode (Cu wire) utilized for this work has been employed in a facile manner that enhances the ease of use for heavy metal electrochemical sensor. Moreover, post‐usage, the replacement of sensor material for subsequent usage is easy. The low cost and simplicity of the method make it ideal for resource‐constrained environments and portability, resulting in increasing the accessibility of water quality monitoring. The study examines the reliability of a low‐cost electrode for Pb concentration detection in water samples to the concentration of 50 μM using a simple low‐cost electrochemical sensor arrangement.

Electrochemical Enrichment of Biocharcoal Modified on Carbon Electrodes for the Detection of Nitrite and Paraxon Ethyl Pesticide

Biocharcoal (BioC), a cost-effective, eco-friendly, and sustainable material can be derived from various organic sources including agricultural waste. However, to date, complex chemical treatments using harsh solvents or physical processes at elevated temperatures have been used to activate and enhance the functional groups of biochar. In this paper, we propose a novel easy and cost-effective activation method based on electrochemical cycling in buffer solutions to enhance the electrochemical performance of biocharcoal derived from almond shells (AS-BioC). The novel electrochemical activation method enhanced the functional groups and porosity on the surface of AS-BioC, as confirmed by microscopic, spectroscopic characterizations. Electrochemical characterization indicated an increase in the conductivity and surface area. A modified SPCE with activated AS-BioC (A.AS-BioC/SPCE), shows enhanced electrochemical performance towards oxidation and reduction of nitrite and paraxon ethyl pesticide, respectively. For both target analytes, the activated electrode demonstrates high electrocatalytic activity and achieves a very LOD of 0.38 µM for nitrite and 1.35 nM for ethyl paraxon with a broad linear range. The sensor was validated in real samples for both contaminants. Overall, the research demonstrates an innovative technique to improve the performance of AS-BioC to use as a modifier material for electrochemical sensors.

Application Progress and Research Status of graphene materials in wearable sensors

Application Progress and Research Status of graphene materials in wearable sensors

Recent Advances in Conductive Polymers-Based Electrochemical Sensors for Biomedical and Environmental Applications.

Electrochemical sensors play a pivotal role in various fields, such as biomedicine and environmental detection, due to their exceptional sensitivity, selectivity, stability, rapid response time, user-friendly operation, and ease of miniaturization and integration. In addition to the research conducted in the application field, significant focus is placed on the selection and optimization of electrode interface materials for electrochemical sensors. The detection performance of these sensors can be significantly enhanced by modifying the interface of either inorganic metal electrodes or printed electrodes. Among numerous available modification materials, conductive polymers (CPs) possess not only excellent conductivity exhibited by inorganic conductors but also unique three-dimensional structural characteristics inherent to polymers. This distinctive combination allows CPs to increase active sites during the detection process while providing channels for rapid ion transmission and facilitating efficient electron transfer during reaction processes. This review article primarily highlights recent research progress concerning CPs as an ideal choice for modifying electrochemical sensors owing to their remarkable features that make them well-suited for biomedical and environmental applications.

Emission Color Tuning of Inverse Type Diarylethene Crystals

AbstractOrganic luminescent solid materials have attracted much attention due to practical applications such as sensor materials and optical waveguides. We have previously reported that inverse type diarylethenes exhibit strong emission in crystal without causing aggregation‐caused quenching. However, the emission color was limited to mainly green. To tune the emission color, in this work, we newly synthesized inverse type diarylethenes having a shortened π‐conjugation length or a polar substituent and investigated their fluorescence properties in solutions and crystals. The crystals exhibited various emission colors from blue, green, yellow to red depending on the molecular structure. The emission color changes of the crystals were induced by the intermolecular interactions such as CH‐π interactions in addition to the shortened π‐conjugation length and the intramolecular charge transfer character.

3D Printed Carbon Nanotubes Reinforced Polydimethylsiloxane Flexible Sensors for Tactile Sensing

Technology is constantly evolving, and chronic health issues are on the rise. It is essential to have affordable and easy access to remote biomedical measurements. This makes flexible sensors a more attractive choice owing to their high sensitivity and flexibility along with low cost and ease of use. As an additional advantage, 3D printing has become increasingly popular in areas such as biomedicine, environment, and industry. This study demonstrates 3D-printed flexible sensors for tactile sensing. A biocompatible silicone elastomer such as polydimethylsiloxane (PDMS) with low elastic modulus and high stretchability makes an excellent wearable sensor material. Incorporating CNTs at varying concentrations (0.5, 1, 2)wt% enhances the sensor’s mechanical strength, conductivity, and responsiveness to mechanical strain. In addition to enhancing the thermal stability of the composite by 44%, multi-walled carbon nanotubes (MWCNTs) also enhanced the breaking strength by 57% with a 2 wt% CNT loading. Moreover, the contact angle values improved by 15%, making it a biomedical-grade hydrophobic surface. The electrical characteristics of these sensors reveal excellent strain sensitivity, making them perfect for monitoring finger movements and biomedical measurements. Overall, 2 wt% CNT-PDMS sensors exhibit optimal performance, paving the way for advanced tactile sensing in biomedical and industrial settings.

Current Strategies for Monitoring and Control of IAQ

The focuses of this paper is on the critical importance of indoor air quality (IAQ) and the need for innovative monitoring systems to enhance occupants' quality of life while balancing energy efficiency. Development of Materials for IAQ Sensors , Enhanced Sensitivity and Selectivity, Miniaturization and Integration, Wireless Connectivity and IoT Integration,Long-Term Stability and Reliability, Cost-Effectiveness and Scalability, Air Purification Technologies for IAQ Improvement, HEPA Filtration, Ionic Air Purification, Photocatalytic Oxidation (PCO), Electrostatic Precipitation, Hybrid Air Purification Systems, Smart Home for IAQ Control Sensor Technology, Data Analytic, Automated Ventilation, Air Filtration and Purification, Smart Thermostats and HVAC Controls, Mobile Apps and User Interfaces,Integration with Smart Home Ecosystems, Air Purification Technologies for IAQ Improvement, . Smart Home for IAQ Control. These strategies collectively empower individuals and building managers to monitor, analyze, and optimize indoor air quality, leading to healthier indoor environments. The use of advanced materials, innovative sensors, and smart technologies enables real-time data-driven decisions, promoting sustainable and effective IAQ management. The overall aim is to mitigate the risks associated with indoor air pollution and ensure that indoor environments remain clean, safe, and healthy for occupants. Ongoing research and technological advancements continue to drive progress in this important field, making IAQ management increasingly accessible and effective for diverse settings and populations.

Endosulfan pesticide detection using an electrochemical sensor based on molecularly imprinted polymer (MIP)

Abstract Pesticides and herbicides are active chemicals used to eradicate plant pests which constitute contamination if they exceed the threshold for the environment and humans. Molecularly Imprinted Polymer (MIP) is a technique for making polymers that are obtained from cross-linked polymers and have cavities that match the template, where the cavities function as a medium for mechanical interaction of molecules with the same size, shape, structure, and physicochemical properties. The polymer produced from the MIP technique is applied to the surface of the sensor material as an endosulfan detection. This research aims to create an endosulfan MIP to obtain a potentiometric MIP sensor capable of detecting endosulfan. The results showed that the optimum conditions for making MIP endosulfan were obtained with a composition of 6.02 mL of chloroform; 0.025 g endosulfan; 0.9 mL methacrylic acid (MAA); 1.57 mL ethylene glycol dimethacrylate acid (EGDMA); 0.07 g benzoyl peroxide with a heating time of 150 minutes at a temperature of 70 °C. The sensor performance test was carried out potentiometrically and it was found that the MIP endosulfan sensor that was made had sensitivity and stability in the concentration range of 0.01-1.0x10−6 ppm with a lifetime up to 90 days.

Corrole Polymers as a Novel Materials for Room Temperature Resistive Gas Sensors

Corrole Polymers as a Novel Materials for Room Temperature Resistive Gas Sensors

Self-Powered Hybrid Motion and Health Sensing System Based on Triboelectric Nanogenerators.

Triboelectric nanogenerator (TENG) represents an effective approach for the conversion of mechanical energy into electrical energy and has been explored to combine multiple technologies in past years. Self-powered sensors are not only free from the constraints of mechanical energy in the environment but also capable of efficiently harvesting ambient energy to sustain continuous operation. In this review, the remarkable development of TENG-based human body sensing achieved in recent years is presented, with a specific focus on human health sensing solutions, such as body motion and physiological signal detection. The movements originating from different parts of the body, such as body, touch, sound, and eyes, are systematically classified, and a thorough review of sensor structures and materials is conducted. Physiological signal sensors are categorized into non-implantable and implantable biomedical sensors for discussion. Suggestions for future applications of TENG-based biomedical sensors are also indicated, highlighting the associated challenges.

Directional Moisture-Wicking Triboelectric Materials Enabled by Laplace Pressure Differences.

Wearable sensors are experiencing vibrant growth in the fields of health monitoring systems and human motion detection, with comfort becoming a significant research direction for wearable sensing devices. However, the weak moisture-wicking capability of sensor materials leads to liquid retention, severely restricting the comfort of the wearable sensors. This study employs a pattern-guided alignment strategy to construct microhill arrays, endowing triboelectric materials with directional moisture-wicking capability. Within 2.25 s, triboelectric materials can quickly and directionally remove the droplets, driven by the Laplace pressure differences and the wettability gradient. The directional moisture-wicking triboelectric materials exhibit excellent pressure sensing performance, enabling rapid response/recovery (29.1/37.0 ms), thereby achieving real-time online monitoring of human respiration and movement states. This work addresses the long-standing challenge of insufficient moisture-wicking driving force in flexible electronic sensing materials, holding significant implications for enhancing the comfort and application potential of electronic skin and wearable electronic devices.

Revealing the Effect of Stereocontrol on Intermolecular Interactions between Abiotic, Sequence-Defined Polyurethanes and a Ligand.

The development of precision polymer synthesis has facilitated access to a diverse library of abiotic structures wherein chiral monomers are positioned at specific locations within macromolecular chains. These structures are anticipated to exhibit folding characteristics similar to those of biotic macromolecules and possess comparable functionalities. However, the extensive sequence space and numerous variables make selecting a sequence with the desired function challenging. Therefore, revealing sequence-function dependencies and developing practical tools are necessary to analyze their conformations and molecular interactions. In this study, we investigate the effect of stereochemistry, which dictates the spatial location of backbone and pendant groups, on the interaction between sequence-defined oligourethanes and bisphenol A ligands. Various methods are explored to analyze the receptor-like properties of model oligomers and the ligand. The accuracy of molecular dynamics simulations and experimental techniques is assessed to uncover the impact of discrete changes in stereochemical arrangements on the structures of the resulting complexes and their binding strengths. Detailed computational investigations providing atomistic details show that the formed complexes demonstrate significant structural diversity depending on the sequence of stereocenters, thus affecting the oligomer-ligand binding strength. Among the tested techniques, the fluorescence spectroscopy data, fitted to the Stern-Volmer equation, are consistently aligned with the calculations, thus validating the developed simulation methodology. The developed methodology opens a way to engineer the structure of sequence-defined oligomers with receptor-like functionality to explore their practical applications, e.g., as sensory materials.

ZnIn2S4 Nanosheets for Efficient NO2 Detection at Room Temperature: Insights into the Role of Sulfur Vacancies.

Engineering atomic vacancies in metal sulfide semiconductors allows for the efficient tuning of their electronic and chemical properties. In this work, we synthesized hollow tubular structures constructed by bimetallic ZnIn2S4 using a metal-organic framework (MOF) as the template. We found that the sulfur vacancies in ZnIn2S4 enabled extremely fast NO2 detection with high response at room temperature (RT), and the material with high sulfur vacancy content delivers a 2 times higher response to 10 ppm NO2 than the device with low sulfur vacancy content. To unveil the crucial role played by sulfur vacancies, DFT calculations were conducted to reveal that sulfur vacancies greatly enhance the interaction and electron transfer between ZnIn2S4 and NO2. This study will provide hints for the engineering of bimetallic sulfide materials for low-power gas sensors at RT.

Advances in Embedded Sensor Technologies for Impact Monitoring in Composite Structures

Embedded sensor technologies have emerged as pivotal tools in redefining structural health monitoring (SHM) within composite materials, addressing a critical need in the composite structure industry. Composites, by their layered nature, are particularly vulnerable to internal delamination and micro-cracks from impacts, which can propagate and lead to catastrophic failures. Traditional inspection methods often fail to detect internal damage and these undetected damages can lead to reduced performance and potential system failures. Embedded sensors offer a solution capable of detecting a spectrum of damages, from barely visible impact damages (BVID) and subtle low-energy impacts to pronounced impact-related deformations, all in real-time. Key sensors, such as Piezoelectric transducers (PZTs), Fiber Bragg Gratings (FBGs), and other potential sensors, have been discussed as potential detection techniques in this review. This review discusses a comprehensive picture of the progress and current scenario of different embedded sensors for SHM of composite structures. The growth of embedded sensor technologies, current limitations, and future requirements focusing on sensor materials have been discussed in this review. Finally, challenges and opportunities for the development of a sustainable SHM system have been discussed in this paper.