Sensor Material Research Articles

Biomimetic Honeycomb-like Ti3C2Tx MXene/Bacterial Cellulose Aerogel-Based Flexible Pressure Sensor for the Human-Computer Interface.

The pursuit of efficient and accurate human-computer interface design urgently requires high-performance sensors with pressure sensitivity, a wide detection range, and excellent cycling stability. Herein, a biomimetic honeycomb-like Ti3C2Tx MXene/bacterial cellulose (BC) aerogel with a negative Poisson's ratio (ν = -0.14) synthesized from the bidirectional freeze-drying method is used as the active material for a flexible pressure sensor, which exhibits high sensitivity (20.14 kPa-1), fast response time (100 ms), excellent mechanical durability (5000 cycles), and a low detection limit (responding to a grain of rice weighing about 0.022 g). Moreover, when assembled into the sandwich-structured bending sensor with the aerogel layer at just 0.8 mm in thickness, the aerogel-based device has a wide angular detection range (2.7-156.3°), high sensitivity (0.47 deg-1), and good robustness, proving outstanding electromechanical performance. Significantly, a smart glove consisting of five bending sensors fixed to the proximal knuckles and a flexible circuit board as the signal processing unit was designed for the identification of the shape, demonstrating its promising applications in the field of human-computer interaction.

Preparation of Flexible Polymer Sensor Material by Spatial Confining Forced Network Assembly Micro Injection Molding

Preparation of Flexible Polymer Sensor Material by Spatial Confining Forced Network Assembly Micro Injection Molding

A Multifunctional Tb(III)-Based Metal-Organic Framework for Chemical Conversion of CO2, Fluorescence Sensing of Trace Water and Metamitron.

The utilization of metal-organic frameworks (MOFs) as fluorescent sensors for the detection of environmental and chemical reagent pollutants as well as heterogeneous catalysis for CO2 conversion represents a crucial avenue of research with significant implications for the protection of human health. In this work, a Tb(III)-based three-dimensional metal-organic framework, [Tb(L)·4DMF]n (Tb-MOF) (H3L = 5'-(4-carboxy-3-hydroxyphenyl)-3,3″-dihydroxy-[1,1':3',1″-terphenyl]-4,4″-dicarboxylic acid), has been structurally conformed by single-crystal X-ray crystallography. It possesses a 1D rhombus channel along the [010] direction, featuring a pore size of 6.02 × 9.13 Å. Tb-MOF was proved to be a multifunctional material for a fluorescent sensor and CO2 cycloaddition heterogeneous catalyst material. Fluorescence sensing studies revealed that Tb-MOF demonstrates high sensitivity, selectivity, and favorable regeneration properties, making it an effective chemosensor for detecting the metamitron (MMT) pesticide and trace water in organic solvents. The mechanism of fluorescence quenching by MMT and water was elucidated by a combination of XRD, UV-vis absorption spectra, IR spectra, theoretical calculations, and fluorescence lifetimes. The material was also utilized for the sensing of MMT and water in paper strips. Additionally, the open Tb3+ site as Lewis acidic centers makes Tb-MOF achieve efficiently catalytic conversion for CO2 and epoxides to cyclic carbonates. Moreover, a possible catalytic mechanism for the conversion of carbon dioxide to cyclic carbonates was proposed by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. It also exhibited recyclability for up to five cycles without noticing an appreciable loss in sensing or catalytic efficiency.

Surface Defect Generation on SnO2 Nanoparticles Using High-Energy Ball Milling for H2S Gas Sensor Applications

Hydrogen sulfide (H2S) is a highly toxic and dangerous gas with a flammable and corrosive nature, making the development of reliable gas sensors for its detection vital. This study investigated the enhancement in H2S gas sensing performance of commercial SnO2 powders after high-energy milling. SnO2 powders were subjected to high-energy milling for 30, 60, and 90 min and then were characterized using advanced techniques to evaluate their morphology, chemical composition, and crystallinity. The response of a pristine SnO2 gas sensor, and ones where the SnO2 was milled for 30, 60 and 90 min, were 2.46, 2.27, 3.01, and 1.98, respectively, to 10 ppm H2S at 300°C. Thus, the H2S gas sensing results revealed that the SnO2 powders milled for 60 min exhibited the highest sensing performance. This improvement in H2S sensing performance was attributable to the reduced particle sizes achieved through the high-energy milling process, which increased the surface area and created defects on the surface of the SnO2 particles, thereby enhancing the interaction between the gas molecules and sensor material. The smaller morphological size of the particles and surface defects subsequently promoted the resistance modulation crucial for H2S gas detection. This study demonstrates that high-energy ball milling can effectively boost the gas-sensing features of SnO2 powders. The findings can provide guidance for enhancing the gas-sensing capabilities of other resistive sensors.

Recent Progress in Surface Acoustic Wave Sensors Based on Low-Dimensional Materials and Their Applications

Benefitting from high sensitivity, rapid response, and cost-effectiveness, surface acoustic wave (SAW) sensors have found extensive applications across various fields, including biomedical diagnostics, environmental monitoring, and industrial automation. Recently, low-dimensional materials have shown great potential in enhancing the performance of SAW sensors due to their exceptional physical, optical, and electronic properties. This review explores recent advancements in the fundamental mechanisms, design, fabrication and applications of SAW sensors based on low-dimensional materials. Specifically, the utilization of low-dimensional materials, including zero-, one- and two-dimensional materials, as sensing materials in SAW sensors are summarized. Their applications in SAW-based gas sensing, ultraviolet light sensing, humidity sensing, as well as biosensing are discussed. Furthermore, major challenges and future perspectives regarding employing low-dimensional materials to enhance SAW sensors are highlighted, providing valuable insights for future research and development in this field.

Flexible Strain Sensor Based on a Dual Crosslinked Network of PAMgA/GL/PANI Antifreeze Conductive Hydrogel

AbstractConductive hydrogels possess excellent flexibility, conductivity, and sensing properties, making them important carrier materials for flexible strain sensors. They show promising application prospects in fields such as human motion detection and artificial intelligence. This paper introduces polyaniline (PANI) and glycerol (GL) into the magnesium acrylate (AMgA) monomer and prepares the polymagnesium acrylate/glycerol/polyaniline (PAMgA/GL/PANI) hydrogel by free radical polymerization method. When the addition of PANI is 9 wt.%, the PAMgA/GL/PANI hydrogel exhibits good mechanical properties, with a tensile strength of 0.385 MPa, an elongation at break of up to 505%, a compressive strength of 1.04 MPa, and its room temperature conductivity is 1.437 S m−1. Even after freezing at −20 °C, its conductivity can still reach 1.254 S m−1. When the tensile deformation of this conductive hydrogel reaches 500%, the gauge factor (GF) reaches 10.33. In addition, the PAMgA/GL/PANI hydrogel also has good self‐healing, adhesion, and moisture retention. These excellent characteristics make it suitable as a flexible strain sensor that can not only accurately monitor human joint movements and subtle physiological signals but also serve as an encrypted information transmission medium.

Conceptual design of TUPI (Timepix4-based Ultra-fast Photon Imaging) detector's hardware

TUPI (Timepix4-based Ultra-fast Photon Imaging) is the new family of direct conversion and vacuum-compatible hybrid detectors under design at Sirius, the Brazilian 4th generation light source. Based on the Timepix4 Application Specific Integrated Circuit (ASIC), it targets different kinds of experiments, such as tomography and spectrometry, and will be used in multiple bioimaging beamlines of Orion, Brazil's Biosafety Level 4 (BSL4) Laboratory project. Also, it will cover a wide energy range (5 to 45 keV) by using different sensors materials (Si, GaAs, CdTe, etc.). Designed in a modular approach to ensure scalability for constructing larger active areas in a compact form, each TUPI module will be composed by a set of 3x side-by-side Timepix4 ASICs to provide a sensitive area of approximately 74×28 mm2 (1344×512 pixels of 55 μm pitch), streaming up to 44 kfps through up to 48×10.24 Gbps optical links directly connected to a Data Acquisition (DAQ) system.

Highly sensitivity and wide-range flexible humidity sensor based on LiCl/cellulose nanofiber membrane by one-step electrospinning

Cellulose is considered an ideal material for flexible electronic humidity sensors due to its green renewable nature, rich surface groups and strong hydrophilicity. However, the traditional cellulose-based humidity sensor cannot simultaneously have wide detection range, high sensitivity and fast response time, which seriously hinder their development and application. Here, an ultrathin Lithium chloride (LiCl)/cellulose nanofiber membrane as moisture sensitive materials was prepared by one-step electrospinning and used to assemble a high-performance humidity sensor. N, N-Dimethylacetamide/Lithium chloride (DMAc/LiCl) solvent system was used to dissolve the cellulose, and DMAc volatilized into the air while LiCl remained in the cellulose nanofibers during the electrospinning process. LiCl as a highly moisture-sensitive inorganic salt has strong hydrophilicity and enhances the moisture sensing detection limit of cellulose fiber (especially under low humidity conditions), thus giving the cellulose moisture sensor excellent sensitivity (up to 4191 %) and a wide detection range (5–98 % RH). The nanometer size of cellulose fibers, the extremely low thickness and large pores of cellulose membranes accelerate the mass exchange of moisture between the air and the membrane, thus giving cellulose humidity sensor a fast response/recovery time (99/110 s) and low hysteresis (2.9 %). Moreover, the performances of humidity sensors didn’t degrade even after being subjected to long-term application (>30 days), high/low temperatures (73.6/0.1 ℃) and thousands of bending cycles. The proposed LiCl/cellulose nanofiber humidity sensor brings innovative solutions for the design of cellulose based sensor with great potential for use in non-contact humidity detection, respiratory monitoring and sleep apnea detection applications.

Sr1-xMxMoO4 (M= Ba, La, Sm and x= 0.05) electrode materials for YSZ-based mixed-potential ammonia sensors under reducing conditions

Sr1-xMxMoO4 (M= Ba, La, Sm and x= 0.05) electrode materials for YSZ-based mixed-potential ammonia sensors under reducing conditions

Adsorption‐Based Electrochemical Sensor Design for the Aqueous Detection of Paracetamol

This study investigates the critical role of adsorption in the development of electrochemical sensors, focusing on carbon (Vulcan XC72R, acetylene black, and graphite) and zeolite (high‐silica ZSM‐5 and all‐silica zeolite β) materials. Based on the paracetamol adsorption characteristics of these materials, an optimized disposable electrochemical sensor is created. This sensor exhibits a linear range of up to 5 μM and a remarkable detection limit of 150 nM (S/N = 3), ≈1000‐time improvement over the blank sensor. Moreover, paracetamol can be measured selectively because glucose has no adsorption affinity for the selected sensor materials. These findings underscore the significance of adsorption properties in sensor material selection in enhancing sensitivity and robustness against interfering species.

A new PVA-κCA double-network hydrogel comprising conductive polyaniline nanofibers for strain sensing applications

AbstractWearable and flexible materials are replacing the conventional solid-state sensors in diffident biomedical applications. Hydrogel-based sensing elements offer several appealing inherent properties such as tissue resembling elasticity, accessibility for modification and robust mechanical performance. Their widely available and affordable raw components in-addition to straightforward synthesis and modification approach make hydrogels appealing material for flexible and wearable sensors in biomedical applications. This work demonstrates the development of new and sensitive material for strain sensing using polyvinyl alcohol (PVA) and κ-carrageenan (κCA) hydrogel comprising conductive polyaniline nanofibers (PANI NFs). The double-network hydrogel was produced via chemical crosslinking of PVA with Glutaraldehyde (GA) and physical crosslinking of κCA with potassium ions in a binary solvent system of deionized water and glycerol. The PANI NFs were then embedded in the hydrogel via the interfacial polymerization (IP) method of polyaniline nanofibers to significantly enhance the material properties and strain sensitivity of the pristine hydrogel. The obtained hydrogel has been involved in rigorous material characterization and sensing capability evaluation. The produced hydrogel demonstrated a high-water content (86.6%), high swelling percentage in acidic solutions, mechanical compressibility up to 60% at 400 kPa, high electrical conductivity of 2.11 S/m, and thermal stability ranging from − 26.9 to 120 oC. The hydrogel resulted in a linear response in its sensing performance of the applied stress (R2 = 0.99). Also, the developed composite demonstrated a sensitivity of 1.5 mV/kPa in stress range from zero up to 170 kPa with response and recovery times of ~ 300 ms and 500 ms, respectively.

Biosensors for measuring nitric oxide NO levels in biosubstrates: a systematic analysis

Nitric oxide NO is a signaling molecule involved in numerous physical and pathological processes in biological systems. Highly sensitive sensor materials for measuring NO amounts in vivo in exhaled air and in body fluids (saliva, blood, urine) can be a useful tool in diagnostics and management of patients with bronchopulmonary, cardiovascular, neurological and tumor diseases. Several approaches to measuring NO in biosubstrates (including exhaled air) have been developed: fluorescence/chemiluminescence, electron spin resonance, electrochemical/amperometric (organic and inorganic) and enzymatic/protein sensors. Semiconductors, transition metal nitrides, phthalocyanine complexes, porphyrin and cobalamin derivatives with metals can serve as materials for NO sensors. Creating sensor materials based on vitamin B12 derivatives is an urgent research task in biomedicine. The article systematizes information on using various compounds as materials for NO-sensitive and selective sensors to measure/evaluate NO levels in various biosubstrates.

Linear NiCo2O4 modified by CuO nanoparticles with wide range and high sensitivity for glucose detection and excellent ultracapacitor performance

To develop materials that can meet the sensing and capacitive performance of glucose. Hydrothermal and electroplating procedures were used to prepare linear NiCo2O4 and nano-CuO particles, respectively. The sensor's sensitivity was 1174.57 μA mM-1 cm-1, with a low detection limit of 0.024 μM (S/N=3), and its detection range was 0.3-12.6 mM, with good stability as verified using an electrochemical workstation. In addition, at a current density of 2 A g-1, this material exhibits a specific capacitance of up to 2140.0F g-1 in supercapacitors. After 5000 cycles, its stability remained at 93.89%. Similarly, asymmetric supercapacitor devices based on nickel foam exhibit A high specific capacitance of 605.5 F g-1 at a current density of 2 A g-1. It is demonstrated that linear NiCo2O4 modified with CuO nanoparticles can be employed not only as a sensitive material for glucose sensors but also for the production of supercapacitors.

ZnO-NF/Graphene/Nafion as electrode platform for some pharmaceutical active ingredients sensor and energy storage applications

This paper presents a simultaneous sensor for the detection of paracetamol (PAR)and ibuprofen (IBU). The sensor is based on a ZnO nanoflower/Graphene/Nafion coated glassy carbon electrode (ZnO NF/GR/Nafion/GCE) and a supercapacitor electrode with the same electrode component. The morphological characterisation of the prepared sensor and supercapacitor electrode was conducted via scanning electron microscopy (SEM), structural characterisation by X-ray diffraction spectroscopy, chemical characterisation by Fourier transform infrared spectroscopy (FT-IR) and Raman analysis. The electroactivity and selectivity of the ZnO NF/GR/Nafion sensor platform towards IBU and PAR were simultaneously investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Electrochemical tests of the sensor were conducted in a three-electrode electrochemical system in 0.1 M B-R buffer (pH 4.0). The linear ranges of the ZnO NF/GR/Nafion sensor towards PAR and IBU were determined in the range of 1.0 and 1000.0 μM. The detection limits for PAR and IBU were calculated as 0.28 µM and 0.31 µM, respectively. In real sample analyses, the efficiency of the investigated sensor in different drug formulations was found to respond to PAR and IBU with high recovery (99.05 % and 103.35 %). The supercapacitor electrode was prepared by changing the same electrode component, amounts and ratios of the components. The performance of the supercapacitor electrode was investigated in the potential range from 0 V to 1.2 V in PVA-H2SO4 electrolyte. The supercapacitor electrode demonstrated a specific capacitance of 488.1 F g−1 at a scan rate of 5 mV s−1 and a capacitance value of 405.5 F g−1 at a current density of 7 mA.cm−2. In this study, the ZnO NF/GR/Nafion/GCE hybrid electrode produced is used as both sensor and supercapacitor electrode material and operates in dual mode. The production method is cheap and simple, and no additional modifications are needed in the production of electrode components. In this study, for the first time in the literature, the electrode material with ZnO NF/GR/Nafion/GCE component is used in the analysis of some pharmaceutical active ingredients and in supercapacitor applications.

Divacancy graphene and graphyne as potential biomedical sensors: A first-principles study

Imbalance in the levels of hydrogen peroxide signals the onset of chronic diseases in our body. Thus, it becomes imperative to design simple material systems with single molecule sensitivity. In this study, we investigate graphene and graphyne based systems by including various vacancy structures to assess their potential as H2O2 sensor materials. From the computed adsorption energies, we select two promising candidates, interestingly both are divacancies in graphene and graphyne. We then investigate electron transport in both the systems using the DFT-NEGF approach. Upon adsorption of H2O2 on the 585 vacancy (a special case of divacancy) in graphene and divacancy graphyne monolayers, we observe distinguishing current-voltage and electron transmission characteristics, in particular, in the former. For the 585 divacancy graphene system through analysis of the electronic properties, we identify the underlying mechanisms responsible for the difference in current values between the clean and H2O2 adsorbed systems, and hence its sensing ability. This work opens up a new avenue of intelligently incorporating vacancy defects in cheaper carbon-based 2D materials to effectively serve as potentially highly sensitive and selective biosensors for early disease detection.

Nickel foam supported CuO/Co3O4/r-GO is used as electrode material for non-enzymatic glucose sensors and high performance supercapacitors

In order to solve the problem of glucose detection in medical development and meet the urgent demand for new energy storage devices, this paper proposes a new material suitable for glucose sensing and capacitive properties. The sensor was fabricated by depositing Co3O4 nanoparticles onto nickel foam with integrated r-GO via the hydrothermal method, followed by the synthesis of CuO nanoparticles using electroplating. The detection range of the sensor is 0.3–11.3 mM. The sensor's sensitivity is 1000.3 μA mM−1 cm−2, indicating its responsiveness to changes in analyte concentration. In electrochemical test systems, Signal-to-Noise Ratio (SNR) usually represents the relative intensity of the effective current signal and the background noise, reflecting the accuracy and reliability of the measurement. When the SNR is three, the minimum detection limit is 0.431 μM, highlighting its ability to reliably detect analytes at low concentrations amidst background noise. According to electrochemical workstation tests, the sensor demonstrates robust stability. Furthermore, the electrode material proves suitable for asymmetric supercapacitor devices, when the current density is 2 Ag−1, the specific capacitance is 660.5 Fg−1. At the same time, we also explore the cyclic stability of the device, which can retain 92.3 % of its initial specific capacitance after 5000 cycles, showing its remarkable long-term stability. In addition, the prepared nanocomposites can also light the red LED light. The results show that the synthesized CuO/Co3O4/r-GO/NF electrode can be used for electrochemical glucose sensing and supercapacitors, and plays an important role as a multi-functional material in the fields of medical, food, electronics, transportation and energy, providing key technical support for a variety of applications.

Zn-doped Co3O4 nanoparticles: promising room temperature sensor materials for efficient triethylamine (TEA) detection

A remarkable Zn-doped Co3O4 nanoparticle material exhibiting exceptional potential as a triethylamine (TEA) sensor was presented. Zn-doped Co3O4 nanoparticles were synthesized using a facile solvothermal method with varying concentrations of zinc dopant. The effects of Zn doping on the sensor triethylamine detection capabilities were investigated, revealing a notable enhancement in sensitivity and selectivity with a response of 2.04 at 25 °C. Furthermore, the calculated response and recovery times at the optimum temperature were 7.5 s and 27.8 s, respectively, making it an energy-efficient and quicker alternative to conventional sensors. This improvement in the sensing performance can be attributed to the optimized electronic structure and chemical properties achieved through Zn doping, which promoted the formation of abundant oxygen vacancies and improved the number of adsorption sites. These findings demonstrate that Zn-doped Co3O4 nanoparticles are promising sensor materials for efficient TEA detection, with potential applications in various industries.

Covalent Organic Framework‐Enhanced Metal Halide Perovskites for Selective and Sensitive Gas Sensing

AbstractSolution‐processed lead‐free halide perovskite gas sensors possess low gas detection limits, offering promising alternatives to traditional metal oxide chemiresistors. However, halide perovskite chemiresistors often suffer from poor selectivity and durability due to a lack of coordinatively unsaturated surface metal ions and their sensitivity to humidity. To address these issues, a general strategy is presented in which the Cs2PdBr6 perovskite surface is coated with covalent organic framework (COF) to provide hybrid sensor materials that are highly sensitive to specific gases and demonstrate excellent stability under real‐working conditions. The hybrid chemiresistors demonstrate high sensitivity and controllable selectivity toward NO2 or NH3 gases. Specifically, TAPB–PDA@Cs2PdBr6 achieves a detection limit of 10 ppb for NO2, the lowest value reported for a perovskite‐based gas sensor, maintaining its performance after continuous exposure to ambient air for several weeks. In contrast, COF‐5@Cs2PdBr6 shows high selectivity to NH3 and has a detection limit of 40 ppb. Structural and spectroscopic characterization combined with mechanistic studies provide molecular‐level insights into the outstanding properties of these new hybrid sensor materials, which set a new benchmark in the field, i.e., surpassing the selectivity and sensitivity of conventional halide perovskite sensors.

Robust and low swelling polyacrylamide/sodium alginate dual-network hydrogels via multiple freezing strategy toward amphibious motion sensors

The swelling and disintegration behavior of conventional hydrogels in liquid environments significantly affects their mechanical and ionic conductive properties, thereby limiting their widespread application in underwater setting. Herein, we propose a multiple freezing (MF) strategy for the construction of polyacrylamide/sodium alginate (PAM/SA) dual-network hydrogels that exhibit excellent anti-swelling properties and high toughness. The MF strategy employs a combination of freeze casting and refreezing to promote a cascading enhancement of polymer network density, resulting in a highly dense polymer network. This dense network structure endows the hydrogel with impressive tensile strength (3.491 MPa), exceptional elongation at break (435.71 %), and high toughness (5.291 MJ m⁻3), along with remarkable ionic conductivity (142.75 mS m⁻1) and sensitivity (GF = 2.278). These properties enable the hydrogel to function as a flexible sensor capable of detecting various human movement patterns. Its excellent resistance to swelling makes it an ideal material for underwater sensors, effectively monitoring different swimming strokes. This strategy provides a straightforward and effective means to enhance the mechanical strength and adaptability of traditional hydrogels in aquatic environments, demonstrating significant potential for applications in underwater sensing.

A Review on Chemistry and Methods of Synthesis of 1,2,4-Triazole Derivatives.

This review provides a comprehensive overview of research on 1,2,4-triazoles conducted over the last fifteen years. 1,2,4-Triazoles are highly significant in the pharmaceutical industry, with numerous compounds from this class used clinically as antifungal, antiviral, antibacterial, anti-inflammatory, and antitubercular agents. Beyond their pharmaceutical relevance, this review also explores their role in material science and agriculture. In material science, 1,2,4-triazoles are gaining prominence, particularly in the development of energetic materials (EMs), due to their exceptional properties such as thermal stability, coordination ability, and performance comparable to well-known explosives. Their applications extend to polymers, corrosion inhibitors, and metal-organic frameworks (MOFs), and they play a significant role in the development of functional materials for sensors, catalysis, and energy storage. Additionally, the review addresses general aspects and synthetic methodologies for the functionalization and construction of the 1,2,4-triazole ring. Synthetic methods discussed include metalation synthesis, cyclization of hydrazine derivatives, multicomponent reactions, cyclization of amides and amidines, and microwave-assisted synthesis. Given the significance of the triazole scaffold, its synthesis has garnered considerable attention due to its wide-ranging applications across various industrial sectors.