Sensor Material Research Articles

Effectively Improved CH4 Sensing Performance of In2O3 Porous Hollow Nanospheres by Doping with Cd.

Recently, due to the promising application of metal oxide semiconductors in high-performance methane (CH4) sensors, more attention has been paid to the development of feasible strategies for improving CH4 sensing performance. Herein, we present a strategy of cadmium (Cd) doping to improve the CH4 sensing property of In2O3 porous hollow nanospheres (PHNSs). The Cd-doped In2O3 PHNSs were prepared via an impregnation-calcination approach with self-made carbon nanospheres as a hard template. The samples were characterized by various techniques to evaluate their structure, morphology, surface state, composition, and band gap. When applied as a sensitive material in the CH4 sensor, the Cd-doped In2O3 PHNSs, compared with bare In2O3 PHNSs, showed some significant improvements in performance, especially a reduced operating temperature (200 °C vs 300 °C), an enhanced response (9.5 vs 2.5 for 500 ppm of CH4), a faster response speed (16 s vs 276 s), and better selectivity. In addition, the Cd-doped In2O3 sensor can also maintain a commendable long-term stability, and the range of its response amplitude within 30 days is only 6.3%. The sensitization effects of the Cd dopant on the In2O3 PHNSs are discussed.

Resistive Heating and Thermal Decomposition of an Additively Manufacturable Electrically Conductive Explosive

AbstractThe ability to transmit electrical signals through high explosive charges without using dense metal conductors could enable continuous monitoring of explosive charges with internally embedded sensors. With the sensor materials themselves being energetic, the impact on the intended detonation performance of the charge can be minimized. Embedded sensors enable real time, in‐situ measurements of conditions relevant to ageing assessments. Additionally, dynamic material property sensing can provide detonation performance data, enabling measurement of dynamic shock position. One proposed method to allow for electronic signal transfer through high explosives is to use electrically conductive explosive composites consisting of an electrically conductive polymer binder mixed with high explosive crystals. These conductive energetic pathways also serve as independently reactive elements and can provide additional functionality via dynamic sensor removal through resistive heating and subsequent decomposition. This work discusses the resistive heating of a previously developed, poly (3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) based, electrically conductive extrudable explosive composite. Experimental samples of the conductive explosive material were subjected to a range of direct current applications and the resulting heating and decomposition of the material is discussed.

High Sensitive and Discriminating Colorimetric Assay for S2- Overload in Adaptogenic Herbs Utilizing ZnS Nanoparticle-Enhanced S, N-Doped Eggshell Membrane-Derived Biochar

BackgroundWith the rapid development of industrialization, the excessive emission of S2− have become increasingly serious, leading to a surge in the content of S2− in nature. Rapid and accurate detection of S2- contamination in natural adaptogens is crucial for food safety. Annually, discarded eggshell waste, rich in organic and inorganic materials, poses environmental risks if landfilled. Utilizing waste eggshell membrane biomass for S2- detection is cost-effective, yet designing biochar materials for sensors requires balancing catalytic enhancement and anti-interference capabilities. Improving the catalytic performance of biochar for colorimetric S2- detection without metal ion interference presents a challenging issue. ResultsWe first modified biochar (EBc) derived from waste eggshell membranes using a combination of thiourea and ZnS nanoparticles, fabricating ZnS-decorated, S-N co-doped biochar (ZnS-SN-EBc) nanozymes, which were applied for the colorimetric assay detection of S2- contamination. The addition of thiourea significantly increases the proportion of pyridinic-N in biochar, enhancing the peroxidase-like activity of the nanozyme. The growth of ZnS nanoparticles on the biochar not only enhances the catalytic performance by increasing the S content but also reduces the content of oxidized S, thereby improving resistance to interference. The detection range for S2- was expanded from 0.1 to 45 μM for EBc to 0.05 to 225 μM for ZnS-SN-EBc, and the limit of detection improved to 0.0397 μM. Additionally, ZnS-SN-EBc significantly enhanced metal ion interference resistance. S2- detection in five types of adaptogenic herbs verified the accuracy and practicality of the colorimetric assay, with recovery rates comparable to national standards. SignificanceWe innovatively repurposed waste eggshell membranes to develop a selective and catalytic peroxidase-like nanozyme, ZnS-decorated S-N co-doped biochar (ZnS-SN-EBc). The developed colorimetric assay utilizing ZnS-SN-EBc demonstrates significant potential for the detection of sulfur ions in adaptogenic herbs, thus contributing to both waste resource utilization and the advancement of food safety detection technologies.

Expression of Concern “ Modeling of Cu, Ag, and Au-decorated Al12Se12 nanostructured as sensor materials for trapping of chlorpyrifos insecticide“ [Comput. Theoret. Chem. 1226 (2023) 114218

Expression of Concern “ Modeling of Cu, Ag, and Au-decorated Al12Se12 nanostructured as sensor materials for trapping of chlorpyrifos insecticide“ [Comput. Theoret. Chem. 1226 (2023) 114218

Mining PANI/Ti3AlC2/CeO2 ternary composite CO sensor: Material synthesis, gas sensing performance and mechanism research

To address the issue of poor gas sensitivity in existing mining semiconductor CO sensor materials like PANI at room temperature, this study employed an ice-water bath in conjunction with an in-situ polymerization method to incorporate 2D sheet-like Ti3AlC2 and nano-CeO2 materials with oxygen vacancies into PANI. As a result, nanometer-sized PANI/Ti3AlC2/CeO2 ternary composite nanomaterial was synthesized. The morphology, synthesis mechanism, and thermal stability of the ternary composite material were investigated using scanning electron microscopy-energy dispersive analysis (SEM-EDS), transmission electron microscopy analysis (TEM), spectral analysis, and thermogravimetric methods. Furthermore, the CO gas sensing mechanism of the ternary composite material was also examined. The study discovered that the nano-PANI/Ti3AlC2/CeO2 ternary composite nanomaterial, when deposited on the Au interdigital electrode of the IDE substrate, exhibits superior gas transmission of 400 ppm CO compared to gas sensors based on nano-PANI, nano-PANI/Ti3AlC2, and nano-PANI/CeO2. The sensing response was enhanced by 1.75 times, 1.4 times, and 1.2 times, respectively. This improvement in sensing mechanism can be attributed to the pn heterojunction and interfacial interaction forces between the components. Hence, the nano-PANI/Ti3AlC2/CeO2 ternary composite nanomaterial holds potential as a high-performance CO detection sensing material at room temperature. Additionally, it can serve as a theoretical basis for further research on low-power, integrable sensor materials in coal mines.

The Adsorption and Sensing Characteristics of Metal‐Calix[4]Arenes Toward Hydrogen Molecule: Density Functional Theory, Perturbation Theory and Molecular Dynamics Approaches

AbstractCalixarenes, which can be functionalized in a wide range of derivatives, are one of the chemicals that should be considered for safe energy storage. This research focused on utilization Density Functional Theory (DFT) method to investigate the hydrogen sensing and adsorption characteristics of two distinct calix[4]arene compounds and their corresponding metal complexes. In the study, electronic sensor properties were investigated by using different approaches. In addition, the dynamic stability was determined by Molecular dynamics (MD) calculations. Perturbation theory analysis has revealed the importance of the relationship between Fe and S atoms. The adsorption energy on the C1 structure with the best adsorption ability was calculated as −10.3 kJ/mol. According to RDG analysis, weak van der Waals interactions play a role in adsorption. The C2‐Fe complex with a substantial decrease in the HOMO–LUMO gap has been identified and explained as an applicant material for electronic sensor against hydrogen molecule. Moreover, it was also determined that the C2‐Fe complex has work function type gas sensor property against hydrogen molecule. According to the results, metal‐calixarene complexes can play an important role in hydrogen safety in the future.

A facile fabrication for the magnetorheological elastomer composed of Fe particles and silicone rubber matrix

Magnetorheological elastomers (MREs), smart materials for sensors, absorbers, and dampers, have attracted great attention. Carbonyl Fe particles integrating an elastomer and additives are often seen. Nonetheless, time-consuming and complicated fabrication processes are encountered, and the carbonyl coating also deteriorates the magnetorheological (MR) effect. This study, to solve these dilemmas, worked on a facile fabrication process, while MREs show proper cyclic stability and good MR effect. The output stress is almost saturated after 30 times of compression. The absolute and relative MR effects of 1.11 MPa and 33.3 % were achieved, and the threshold value is located between 16Fe and 24Fe composites.

Assessing Wear Characteristics of Sprayable, Diacetylene-Containing Sensor Formulations

This work extends recent developments in diacetylene-based, sprayable sensors by identification and assessment of formulations which facilitate their use for wearable sensing. Diacetylene-based spray-on sensors have the potential to be a widely deployed sensing technology, as they require no power and can be applied as thin coatings onto surfaces to provide a colorimetric response to target exposure. In responding to radiation, liquid-phase targets, or gas-phase targets specifically determined by the formulation of the sprayable sensor used, this technology is amenable to wearable sensors for measuring exposure to different environmental risks. Here, we provide the means to improve wear resistance, reduce false-positive signals due to wetting, and enhance color fastness for coatings of sprayable, diacetylene-based sensor formulations on cotton fabric. These sensor formulations possess polymethyl methacrylate (PMMA), which enhances the coating stability to only 8% color loss due to wear compared to 18–25% without PMMA, while maintaining the inherent ability of diacetylene-component formulations to detect radiation as well as gas or liquid phase analytes. This represents a significant step toward the use of diacetylene-based sensing formulations for wearable sensing. In the future, the form of spray-on sensor materials demonstrated here may find use in wearable sensing applications for detection of cumulative exposure to UV radiation, hydrogen peroxide vapors, or solvent exposure. We expect trends toward applications toward other wearable sensors for environmental monitoring given the well-known customizability in target response of diacetylene-containing monomers by modifying their headgroup chemistry.

A Flexible Organomagnetic Single-Layer Composite Film with Built-In Multistimuli Responsivity.

Materials possessing multiple properties and functionalities, that can be controlled or modulated by external stimuli, are a central focus of current research in materials sciences due to their potential to significantly enhance various future technological applications. Herein, we report a significant advancement in this field through the development of a smart, multifunctional organomagnetic composite material. By utilizing a thin layer of polydimethylsiloxane (PDMS) and polypyrrole (PPy) precursors, doped with nickel nanoparticles (NiNPs), we have created an innovative organomagnetic, PDMS/PPy/NiNPs (PPN), single-layer composite film that displays multistimuli responsivity. The study presents the first demonstration of a multifunctional flexible, three-component film structure integrating the structural and flexible PDMS component, together with a conductive polymer component and metal-based nanoparticles into a single-layer design, which displays enhanced and unprecedented responsivity properties against multiple different stimuli. Unlike typical stacked multilayered structures, that exhibit one or two functionalities at most, this novel configuration exhibits multiple functionalities, including magnetoresistance, mechanical stress response, piezoresistivity, and temperature change sensitivity. The as-prepared film demonstrates notable magnetoresistance responsivity, with a relative electrical resistance, ΔR/R0, changing under a weak magnetic field and under ambient conditions. The significance of our study lies in the film's versatility, stability, and sensitivity, especially within the physiological temperature range, making it highly relevant for future biomedical applications. Furthemore, the film's sensitivity to mechanical deformation reveals an impressive piezoresistance behavior. Unlike existing multilayer architectures of higher complexity, our single-layer thin film offers a simpler, more flexible, and reliable solution with a broad range of stimuli-sensing capabilities. The significance of this novel multiresponsive composite material is underscored by the growing demand for advanced materials in biomedical devices, magnetic switches, sensors, electronic skin, transistors, and organic spintronic devices. These promising organomagnetic self-standing layers provide a robust platform for future technological innovations.

Progress in Protein-Based Hydrogels for Flexible Sensors: Insights from Casein.

In recent years, the rapid advancement of flexible sensors as the cornerstone of flexible electronics has propelled a flourishing evolution within the realm of flexible electronics. Unlike traditional flexible devices, hydrogel flexible sensors have characteristic advantages such as biocompatibility, adhesion, and adjustable mechanical properties and have similar properties to human skin. Especially, biobased hydrogels have become the preferred substrate material for flexible sensors due to increased environmental pressures caused by the scarcity of petrochemical resources. In this regard, proteins possess advantages such as diverse amino acid compositions, adjustable advanced structures, chemical modifiability, the application of protein engineering techniques, and the ability to respond to various external stimuli. These enable the hydrogels constructed from them to have greater designability, flexibility, and adaptability. As a result, their applications in manufacturing various types of sensors have experienced rapid growth. This work systematically reviews the sensing mechanism of protein-based hydrogels, focusing on the preparation of protein-based hydrogels and the optimization of flexible sensors mainly from the perspective of a typical type of animal-derived protein casein. In addition, while the potential of casein is recognized, the limitations of casein-based hydrogels in flexible sensor applications are explored, and insights are provided into the development trends of next-generation sensors based on casein-based hydrogel materials.

Promising LVHCL material for nonlinear optical devices and pyroelectric sensors

Promising LVHCL material for nonlinear optical devices and pyroelectric sensors

Ultrathin Copper Monosulfide Films for an Optically Semitransparent, Highly Selective Ammonia Chemosensor.

Transition-metal sulfides are emerging as promising materials for chemiresistive gas sensors─a field still dominated by semiconducting metal oxides. Despite the availability of materials with tunable electronic, optical, physical, and chemical properties, few studies have moved beyond synthesis to provide strategies for enhancing gas sensing performance through material modification. Here, we present a simple, scalable synthetic strategy for developing an optically semitransparent, flexible NH3 gas sensor with a highly uniform, ultrathin CuS (covellite) active sensing layer. The optical and chemical properties of the CuS were precisely controlled near the percolation threshold of thin-film formation by varying key experimental parameters such as the Cu film thickness (<10 nm) and the sulfurization time (∼90 s) under ambient conditions. Experimental and computational studies of CuS and its NH3 sensing characteristics identify key physicochemical properties. The controlled surface chemistry and morphology of the ultrathin CuS layer demonstrate its effectiveness in functional NH3 sensing devices, which achieve a calculated detection limit of 1.38 ppm for NH3 gas at 150 °C, along with exceptional mechanical robustness and optical semitransparency in the visible-light spectrum.

BODIPY-based fluorescent sensor material for airborne acetone and benzene with aggregation-driven selectivity

Paper highlights advances in design of fluorescent sensors for solvent vapors with boron-dipyrromethene (BODIPY) as a model active component. The present study demonstrates that BODIPY-based fluorescent materials could be successfully utilized for detection of benzene and acetone in gas phase. Concentration of luminophore was found to affect sensory response to benzene (up to 3-fold increase in adjusted conditions). At the same time, sensory response to acetone is concentration-independent, suggesting different underlying response mechanisms and allowing to tune selectivity with choice of concentration. Detection limits achieved for sensory materials are 1.2·104 mg/m3 for acetone and 0.94·104 mg/m3 for benzene. Ultimately, obtained sensor materials could be completely regenerated without need for inert gas purge.

Novel Approach for Lifetime-Proportional Luminescence Imaging Using Frame Straddling.

Optode-based chemical imaging is a rapidly evolving field that has substantially enhanced our understanding of the role of microenvironments and chemical gradients in biogeochemistry, microbial ecology, and biomedical sciences. Progress in sensor chemistry has resulted in a broadened spectrum of analytes, alongside enhancements in sensor performance (e.g., sensitivity, brightness, and photostability). However, existing imaging techniques are often costly, challenging to implement, and limited in their recording speed. Here we use the "frame-straddling" technique, originally developed for particle image velocimetry for imaging the O2-dependent, integrated luminescence decay of optical O2 sensor materials. The method synchronizes short excitation pulses and camera exposures to capture two frames at varying brightness, where the first excitation pulse occurs at the end of the exposure of the first frame and the second excitation pulse at the beginning of the second frame. Here the first frame truncates the luminescence decay, whereas the second frame fully captures it. The difference between the frames quantifies the integral of the luminescence decay curve, which is proportional to the luminescence lifetime, at time scales below one millisecond. Short excitation pulses avoid depopulation of the ground state of luminophores, resulting in a linear Stern-Volmer response with increasing concentrations of the quencher (O2), which can be predicted through a simple model. This methodology is compatible with a wide range of camera systems, making it a versatile tool for various optode based chemical imaging applications. We showcase the utility of frame straddling in measuring O2 dynamics around algae and by observing O2 scavenging sodium dithionite particles sinking through oxygenated water.

Tailoring of Ultrasmall NiMnO3 Nanoparticles: Optimizing Synthesis Conditions and Solvent Effects

Nickel manganese oxide (NiMnO3) combines magnetic and dielectric properties, making it a promising material for sensor and supercapacitor applications, as well as for catalytic water splitting. The efficiency of its utilization is notably influenced by particle size. In this study, we investigate the influence of thermal treatment parameters on the phase composition of products from alkali co-precipitation of nickel and manganese (II) ions and identify optimal conditions for synthesizing phase-pure nickel manganese oxide. Ultrafine nanoparticles of NiMnO3 (with sizes as small as 2 nm) are obtained via liquid-phase ultrasonic dispersion, exhibiting a narrow size distribution. A systematic exploration of the solvent nature (water, N-methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide) on the efficiency of ultrasonic dispersion of NiMnO3 nanoparticles is provided. It is demonstrated that particle size is influenced not only by absorbed acoustic power, dependent on the physical properties of the used solvent (boiling temperature, gas solubility, viscosity, density) but also by the chemical stability of the solvent under prolonged ultrasonic treatment. Our findings provide insights for designing ultrasonic treatment protocols for nanoparticle dispersions with tailored particle sizes.

Study of the magnetic and structural properties of the simple perovskite YFeO3

In the present work, an experimental and theoretical study of the synthesis, magnetic, and structural properties of simple perovskite compounds YFeO3 has been investigated based on their potential applications, such as: solid oxide fuel cells, electrochemical sensors, sensor materials, magneto-optical materials, etc. Experimentally, the synthesis was carried out by the sol-gel method. X-rays and Rietveld refinements confirmed the orthorhombic structure. Scanning electron microscopy observations confirmed agglomerates of simple perovskite particles YFeO3. The study of the magnetic phase of the simple perovskite YFeO3 showed that it behaves like a weak ferromagnetic, this property delimits and directs magnetic fields into well-defined trajectories. On the other hand, the structural results, from a theoretical point of view, are in good agreement with the experimental ones. Through energy comparison, a possible competition was identified between the FM and AFM states, where the electronic properties are associated with the directional nature of the hybridization between the p orbitals of oxygen and the t2g states, where the superexchange mechanism prevails with e oxygen as mediator.

Angle-dependent ion-beam etching of RuAl thin films for structuring GHz-frequency electronics

The ruthenium aluminide (RuAl) alloy is a promising electrode material for wireless surface acoustic wave sensors working under harsh conditions at high temperatures. However, during the structuring of RuAl thin films using ion-beam etching, etched material can redeposit at the edges of the electrodes and form objects, so-called fences, on top of the structured features. These decrease the high-temperature stability and lead to an undesired alteration of the sensor performance. In this work, the angle-dependent ion-beam etching of RuAl thin films was investigated to inhibit the formation of such fence structures. The etch rate was determined as a function of the etching angle between ion-beam and sample surface in a range between 90° and 40°. Furthermore, finger structures with pitches below 500 nm, which are required for devices working in the intended GHz regime, were patterned to study the influence of the etching angle on the profile of the RuAl electrode fingers using transmission electron microscopy and energy-dispersive x-ray spectroscopy. The results show that an etching angle of 50° results in the highest etch rate. For etching angles of 50° and below, the width of the fences is reduced below 10 nm, so they break off during standard resist removal procedures. Such low etching angles lead to shadowed areas on the side of structured features in which unetched material remains. However, this material can be removed by using a two-step etching process combining a 50° step with a 90° step. This process is capable of structuring fence-free trapezoidal-shaped electrode finger profiles. Therefore, the developed process is well suited for the fabrication of high-temperature GHz-frequency RuAl electrodes.

An intelligent CFRP bolt with embedded carbon nanotube eddy current sensors for damage self‐diagnosis of bolted composite joints

AbstractRecognizing the critical demand for composite bolts and the damage‐mode complexity of composite bolt joints, this study introduces the concept of an intelligent carbon fiber reinforced polymer (CFRP) bolt, which achieves self‐monitoring of damage in small and complex CFRP bolted joints. The proposed eddy current sensor (ECS) is mainly composed of a coil made of carbon nanotube film and encapsulated with epoxy resin film. This achieves homogeneous embedding of the sensor by using the same material for both sensor and bolt. The CFRP bolt is fabricated by molding process, with the proposed ECS embedded in bolt shank. The numerical simulation results indicate that hole‐edge damages impact the distribution of induced current density and eddy current flow in CFRP plates. Additionally, the impedance amplitude of the ECS effectively monitors bearing damage propagation. Shear tests confirm that the integration method of the proposed ECS within the CFRP bolt introduces negligible intrusion to the host bolt's integrity. Experimental results demonstrate that the intelligent CFRP bolt can effectively monitor the damage propagation at the hole edge, with an accuracy for bearing damage exceeding 0.5 mm. At a working frequency of 10 MHz, the sensor's sensitivity in detecting a 0.5 mm bearing damage reaches 4.20%.Highlights An intelligent CFRP bolt was fabricated using the molding method. The embedding of the ECS did not cause adverse effects on the bolt. The proposed EC sensor is composed of carbon nanotube and epoxy resin adhesive films. The eddy current distribution at the hole edge of the CFRP bolted joints is analyzed. The ability of intelligent bolts to monitor hole edge damage is verified by experiments.

Reaction-driven restructuring of defective PtSe2 into ultrastable catalyst for the oxygen reduction reaction.

PtM (M = S, Se, Te) dichalcogenides are promising two-dimensional materials for electronics, optoelectronics and gas sensors due to their high air stability, tunable bandgap and high carrier mobility. However, their potential as electrocatalysts for the oxygen reduction reaction (ORR) is often underestimated due to their semiconducting properties and limited surface area from van der Waals stacking. Here we show an approach for synthesizing a highly efficient and stable ORR catalyst by restructuring defective platinum diselenide (DEF-PtSe2) through electrochemical cycling in an O2-saturated electrolyte. After 42,000 cycles, DEF-PtSe2 exhibited 1.3 times higher specific activity and 2.6 times higher mass activity compared with a commercial Pt/C electrocatalyst. Even after 126,000 cycles, it maintained superior ORR performance with minimal decay. Quantum mechanical calculations using hybrid density functional theory reveal that the improved performance is due to the synergistic contributions from Pt nanoparticles and the apical active sites on the DEF-PtSe2 surface. This work highlights the potential of DEF-PtSe2 as a durable electrocatalyst for ORR, offering insights into PtM dichalcogenide electrochemistry and the design of advanced catalysts.

Pd-anchored VSe2 for glucose sensing: Prediction from first principle simulations

Accurate detection of glucose molecule is clinically important for treatment of diabetes. The sensor should efficiently detect the glucose molecule with suitable response time. The conductivity of the sensor material thus plays a vital role in fast and precise sensing. Layered vanadium di-selenide (VSe2) is a transition metal dichalcogenide (TMDC) with metallic characteristics. The current study is to portray a theoretical exhaustive investigation about enhancement in effectual detection of glucose using VSe2 decorated with transition metals (TM) such as Ag and Pd. We have performed extensive DFT simulations to relate adsorption energy of glucose with pristine and decorated VSe2. Introduction of TM to pristine VSe2 was found to increase the adsorption energy of glucose which increases the sensitivity of metal- anchored VSe2. Comprehensive partial density of states (PDOS) and total density of states (TDOS) analysis has been carried out to analyse orbital interaction and qualitative charge transfer which has also been measured using Bader charge analysis. In addition to that, permanency of the best decorated system has been verified through molecular dynamics calculation and modality of recurrent serviceability has been determined by means of recovery time estimation. This is crucial since as on today, most of the available glucose detectors are meant for single usage. Our theoretically derived findings clearly point to the prediction that TM-decorated layered VSe2 can be an efficient glucose sensor, if practically developed in forthcoming times. The obtained results will thus potentially be beneficial for experimentalists for scheming and evolving VSe2-based glucose sensors.