Low Recovery Time Research Articles

Mechanism and Performance Evaluation of a Strain Sensor Made from a Composite Hydrogel Containing Conductive Fibers of Thermoplastic Polyurethane and Polyvinyl Alcohol.

Monitoring human physiological conditions using flexible, stretchable strain sensors is an effective approach to prevent and treat critical illnesses, emergencies, and infectious diseases. However, achieving ultralow detection limits, high sensitivity, and a wide detection range in a cost-effective manner is challenging. In this study, a strain sensor was developed by embedding an adhesive hydrogel composed of polyvinyl alcohol, starch, and glutaraldehyde into conductive fibers made from thermoplastic polyurethane. By leveraging the high sensitivity of the conductive fibers and the wide detection range of the hydrogel, a robust dual-layer continuous conductive network was formed through their synergistic interaction. Tensile strength tests and other assessments indicated that the sensitivity of the sensor increased from a gauge factor of 49.32 (for fiber-based sensors) to 74.18, while the detection range expanded from 250 to 400%. Furthermore, the sensor demonstrated a low detection limit (0.6%), fast response and recovery times (80 ms/120 ms), and durability exceeding 800 cycles. Tests on pulse monitoring, joint movement, and voice recognition confirmed the significant applicability of the sensor for real-time monitoring of various physiological activities throughout a human's life. This study aims to provide technical support for the development of flexible wearable systems.

Dual‐active‐layer flexible piezoresistive sensor based on wrinkled microstructures and electrospun fiber network for human‐related motion sensing applications

AbstractFlexible pressure sensors with high sensitivity and a wide detection range must be developed for practical applications. In this study, a dual‐active‐layer flexible piezoresistive sensor was developed. A reduced graphene oxide film with wrinkled microstructures was prepared by a simple and low‐cost substrate pre‐stretching method and used as the first active layer. A thermoplastic polyurethane electrospun fiber membrane was modified by fast polydopamine coating and ultrasonication with multi‐walled carbon nanotubes and used as the second active layer. Owing to the continuously changing conductive pathways created by the wrinkled microstructures and fiber network under pressure deformation, the sensor achieved a detection range of 0–100 kPa, with sensitivities of 8.5, 1.35, and 0.39 kPa−1 in the ranges of 0–1, 1–20, and 20–100 kPa, respectively. Additionally, the sensor exhibited a low detection limit (2 Pa), response and recovery times of 105 and 85 ms, respectively, and reliable service performance over 10,000 loading/unloading cycles. The sensor enabled real‐time monitoring of finger and wrist bending, beaker‐holding, and fingertip‐sliding on a touch screen, demonstrating its feasible applications in wearable electronics and human–machine interface devices.

Multifunctional and flexible sensor based on PU-supported Au/VTe2/Ti3C2Tx yarns for human motion and NO2 detection

Given the considerable harm that NO2 poses to the environment and human health, developing reliable NO2 detection sensors is crucial. Herein, a flexible, multifunctional sensor was successfully synthesized through hydrothermal and the wet impregnation methods using an elastic PU yarn as the substrate. This sensor, named Au/VTe2/Ti3C2Tx–PU, was characterized via X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy to analyze its structure, chemical valence states, and micromorphology. At room temperature (23 °C), the sensor demonstrated an exceptionally high response to NO2 gas, with a response value of 1.72 at 50 ppm as well as low response and recovery time of 33 and 38 s. Additionally, testing of the strain performance of Au/VTe2/Ti3C2Tx–PU showed that this flexible sensor exhibits high strain sensitivity, excellent repeatability, and durability, making it suitable for detecting subtle human movements. Overall, the synthesized sensor is in considerable advantages in terms of both gas-sensing performance and tensile performance, exhibiting broad application prospects in human motion and health monitoring.

Comprehensive data security and compliance framework for SMEs

Small and Medium-sized Enterprises (SMEs) are increasingly relying on cloud platforms to support critical business operations, making effective disaster recovery (DR) strategies essential for ensuring business continuity. This review proposes a robust disaster recovery framework tailored for SMEs, designed to minimize downtime and data loss in the event of a system failure, cyberattack, or natural disaster. The framework integrates advanced cloud technologies to create a cost-effective, scalable solution that aligns with the resource constraints of SMEs while providing enterprise-grade resilience. Key components of the disaster recovery framework include cloud-based data replication, automated backup solutions, and geo-redundant storage to ensure that data is continuously available and recoverable. This model employs real-time data synchronization and incremental backups to minimize Recovery Point Objectives (RPO), ensuring that critical data is not lost during an unexpected outage. Additionally, the framework leverages automated failover mechanisms to achieve low Recovery Time Objectives (RTO), allowing businesses to restore operations quickly after an interruption. Cloud orchestration tools such as AWS Elastic Disaster Recovery or Azure Site Recovery are utilized to automate disaster recovery processes, reducing manual intervention and improving the speed of recovery. The framework also incorporates regular testing of disaster recovery plans, using simulation tools to identify weaknesses and optimize response times. For SMEs, cost-effectiveness and ease of management are crucial. The framework emphasizes a pay-as-you-go model for cloud resources, allowing businesses to scale their disaster recovery solutions as they grow without incurring excessive upfront costs. By providing continuous monitoring and proactive threat detection, this disaster recovery framework ensures that SMEs can maintain uninterrupted business operations on cloud platforms, thereby enhancing resilience and mitigating the financial and operational risks associated with data loss and system downtime.

Using superconducting single photon detector to improve the coupling efficiency of multimode fibers in the telescope ranging system

The receiving system adopts the coupling manner of space beam and the multimode fiber among some space target laser ranging system. The fiber coupling efficiency can affect the number of echo photons and ranging accuracy, especially in lunar laser ranging, high orbit satellite laser ranging and space debris tracking. This article proposes a method utilizing the telescope pointing technique and a four-pixel superconducting nanowire single photon detector (SNSPDs) to measure coupling efficiency of multimode fiber. SNSPDs has the excellent performance with high detection efficiency, low dark count rate, and low recovery time. In the experiment, SNSPDs receives the changing signals caused by adjusting the offset angle of the telescope. The root mean square of deviation between measured results and theoretical calculations is 4.48%. The method is based on existing laser ranging systems and is suitable for scientific engineering verification of optical fibers already installed in the system and monitoring of system status.

Recyclable Bimodal Polyvinyl Alcohol/PEDOT:PSS Hydrogel Sensors for Highly Sensitive Strain and Temperature Sensing.

Multimodal flexible sensors, consisting of multiple sensing units, can sense and recognize different external stimuli by outputting different types of response signals. However, the recovery and recycling of multimodal sensors are impeded by complex structures and the use of multiple materials. Here, a bimodal flexible sensor that can sense strain by resistance change and temperature by voltage change was constructed using poly(vinyl alcohol) hydrogel as a matrix and poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) as a sensing material due to its conductivity and thermoelectric effect. The plasticity of hydrogels, along with the simplicity of the sensor's components and structure, facilitates easy recovery and recycling. The incorporation of citric acid and ethylene glycol improved the mechanical properties, strain hysteresis, and antifreezing properties of the hydrogels. The sensor exhibits a remarkable response to strain, characterized by high sensitivity (gauge factor of 4.46), low detection limit (0.1%), fast response and recovery times, minimal hysteresis, and excellent stability. Temperature changes induced by hot air currents, hot objects, and light cause the sensor to exhibit high response sensitivity, fast response time, and good stability. Additionally, variations in ambient humidity and temperature minimally affect the sensor's strain response, and temperature response remains unaffected by humidity changes. The recycled sensors are essentially unchanged for bimodal sensing of strain and temperature. Finally, bimodal sensors are applied to monitor body motion, and robots to sense external stimuli.

The design of CN/C3N2 heterostructures and the potential as gas sensor and scavenger for SF6 decomposed gases

The design, electronic and gas-sensing properties of the CN/C3N2 heterostructures with and without the adsorption of H2S, SO2, HF, SOF2, and SO2F2 were systematically investigated by using DFT calculations. All SF6 decomposition gases can physically adsorb on both sides of the CN/C3N2 heterostructure with significant adsorption strength and charge transfer. Although the adsorption of these gases, in general, hardly affects the electronic properties, but can remarkably tune the work function (Φ) of the heterostructure. The CN/C3N2 heterostructure as Φ-type gas sensors has an ultra-high sensitivity for SF6 decomposed gases (at least over 71.2 %), especially for the C3N2 side (at least over 568.7 %), and has relatively low recovery times for HF, H2S, SOF2, and SO2F2 gases at 300 K, indicating the reusability of the heterostructure at room temperature, but much more favorable at 350∼400 K for SO2 gas. Further, the heterostructure as adsorbents for the capture and scavenging of SF6 decomposition gases has high adsorption capacity and strength. Therefore, our findings reveal that the CN/C3N2 heterostructure is a promising candidate as Φ-type gas sensors with high sensitivity and reusability for the detection of SF6 decomposition gases, while as an optimal scavenger for removing these toxic gases.

2D Materials‐Based Pulsed Solid‐State Laser: Status and Prospect

AbstractPulsed solid‐state lasers comprise 2D materials as saturable absorbers that contain transparent windows of the atmosphere and characteristic fingerprint spectra of several vital molecules that are significant in various applications and research. Over the past few decades, significant progress has been made in the development of narrow pulse width, high energy, high average output power, high efficiency, and simple construction of passively Q‐switched and mode‐locked lasers with 2D materials as saturable absorbers. This review summarizes the development of 2D materials, including graphene, transition metal dichalcogenides, black phosphorus, topological insulators, and MXenes, as modulator devices for solid‐state lasers owing to their broadband operation, excellent nonlinear optical response, low recovery time, ultrafast dynamic processing, and easy fabrication. Then, some new emerging and representative applications of pulsed solid‐state lasers are introduced and illustrated such as laser surgery, material processing, and lidar. Finally, future challenges and perspectives of pulsed solid‐state lasers with 2D materials‐based saturable absorbers are analyzed and addressed. The rapid development of pulsed solid‐state lasers with the continuous improvement of modulation technology is expected to expand opportunities for application in industry, scientific, medical, and other areas.

Eco-friendly, stimuli-responsive sponge with magneto-photothermal effect for efficient and continuous cleanup of viscous crude oils

Oil spills pose significant global environmental and resource wastage issues due to the slow flow of high-viscosity crude oil. Current cleanup methods, such as chemical dispersion, in situ burning, microbial degradation, and mechanical oil skimmers, have limitations such as low recovery rates, secondary pollution, and time consumption. To address these challenges, we developed an eco-friendly magneto-photothermal sponge combining magnetic and photothermal heating. This innovation enables safe, efficient, and continuous cleanup without direct contact. The magneto-photothermal sponge, fabricated through a simple dip-coating and template method, consists of nontoxic polydimethylsiloxane (PDMS) sponge with a biocompatible SiO2/Fe3O4/polydopamine layer. It exhibited rapid adsorption, high capacity (131–344 % for various oils), sustained superhydrophobicity, and reusability. Owing to its magnetothermal and photothermal properties, it was rapidly heated to 178 °C in 3 min under an alternating magnetic field and to 63.5 °C in 5 min under solar irradiation. The sponge efficiently absorbed viscous crude oils, with a recovery rate of 93.33 g h−1 cm−2, which surpasses that reported in previous studies. Combining solar and magnetic heating enhanced recovery, being 13 and 1.2 times more effective than individual solar and magnetic heating, respectively. This low-cost, high flame retardant, durable, dual-heating approach offers an efficient, safe, and eco-friendly solution for cleaning viscous heavy oil spills.

Growth mechanism and the properties of CIGS thin films for zero bias photodetector devices

CuInGaSe2 quaternary thin films have been deposited using a single-source, single-step thermal evaporation technique using hydrothermally fabricated CIGS powder. Highly crystalline, homogeneous, and stoichiometric CIGS powder source was prepared by a hydrothermal method and then evaporated at substrate temperatures of room temperature, 150°C, and 300°C. The bulk and surface structural, morphological, and optical properties of the samples were analyzed. The sample deposited at room temperature did not show any phase formation; however, increasing the substrate temperature resulted in the formation of binary and quaternary phases due to interdiffusion of the species. XPS and Raman spectra analysis revealed nanocrystalline Cu2Se phase formation at the interface, while the bulk of the sample remained single-phase CIGS. A higher deposition temperature also facilitated larger grain size and a more compact surface morphology. Increasing the substrate temperature increased the likelihood of interdiffusion of the species from the evaporation flux and controlled the bulk and surface properties of the samples. CIGS/CdS active photodetectors were fabricated by deposition of a CdS buffer layer, with the sample deposited at 150°C showing the highest photocurrent along with low response and recovery times at 0 V bias.

First principles investigation on zigzag nanoribbons of X-Nitrides (X=B,Al,Ga) for hydrogen cyanide gas sensor

This paper investigates the structural, electronic and transport calculations of varies zigzag nitride nanoribbons using DFT-framework. Based on the binding energy calculations, it is noticed that configuration bare ZXNNR with width 6 is found most structurally stable. The bare ZXNNR exhibits metallic behavior and band gap variation is also observed in pristine ZXNNR in decreasing order as increase in the width. Further, we have calculated the selectivity and recovery time of the considered structures. The highest selectivity is noticed in ZBNNR configuration. The ZGaNNR-HCN‘ configuration has lowest recovery time (56μs).The configuration ZGaNNR shows strong potential towards designing of low power and extremely fast hydrogen cyanide gas sensor applications. Present findings show that adsorption of HCN molecule can be sensed by current passing through the nanoribbons.

Low hysteresis, high sensitivity, fast response, and recovery time of humidity sensor based on Schiff bases material

Low hysteresis, high sensitivity, fast response, and recovery time of humidity sensor based on Schiff bases material

Design of a Humidity Sensor for a PPE Kit Using a Flexible Paper Substrate.

The present work reports the rapid sweat detection inside a PPE kit using a flexible humidity sensor based on hydrothermally synthesized ZnO (zinc oxide) nanoflowers (ZNFs). Physical characterization of ZNFs was done using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR), UV-visible, particle size analysis, Raman analysis, and X-ray photoelectron spectroscopy (XPS) analysis, and the hydrophilicity was investigated by using contact angle measurement. Fabrication of a flexible sensor was done by deposition on the paper substrate using the spin coating technique. It exhibited high sensitivity and low response and recovery times in the humidity range 10-95%RH. The sensor demonstrated the highest sensitivity of 296.70 nF/%RH within the humidity range 55-95%RH, and the rapid response and recovery times were also calculated and found as 5.10/1.70 s, respectively. The selectivity of the proposed sensor was also analyzed, and it is highly sensitive to humidity. The humidity sensing characteristics were theoretically witnessed in terms of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and electronic properties of sensing materials in ambient and humid conditions. These theoretical results are evidence of the interaction of ZnO with humidity. Overall, the present study provides a scope of architecture-enabled paper-based humidity sensors for the detection of sweat levels inside PPE kits for health workers.

Boron-nitride nanostructures for the detection of harmful gases (CO, CO2, H2S, N2O, and SO2)

Boron-nitride (BN) structures are considered materials with several applications, including sensing platforms. Through density functional theory calculations based on the PBE-D3/6-311G(d,p) level of theory, we propose the boron-nitride nanosheet, armchair nanotube (5,5), and fullerene as possible sensors for the harmful gases CO, CO2, H2S, N2O, and SO2. According to our results, the systems exhibit adsorption energies of −0.10 eV to −1.26 eV, and remarkable electronic parameters such as chemical potential, energy gap, and HOMO and LUMO energies, ideal for serving as chemical sensors of such pollutant gases. The nanostructures can be selective to sense a particular gas, mainly CO, N2O, and SO2. Additionally, we note a dramatic change in the electrical conductivity up to 2.14 eV, and low recovery time from 15 μs to 6.2 s. Finally, the BNNS-SO2, BNNT-N2O, BNNT-SO2, and BNF-CO are the more promissory systems to be used as chemical sensors of SO2, N2O, and CO.

Investigating the unique entropy-elasticity of polymer modified asphalt

Crafting Styrene-Butadiene-Styrene (SBS) polymer into the bitumen can notably improve the elastic response of the polymer modified bitumen (PMB), which will significantly enhance the overall performance of bituminous pavement. But the molecular mechanism of the PMB’s unique entropy elasticity has not been fully understood yet. The prominent entropy-elasticity of SBS polymer modified asphalt was investigated in this study. To do so, Fourier Transform Infrared (FTIR), Gel Permeation Chromatography (GPC) and Dynamic Mechanical Analysis (DMA) were conducted to investigate the molecular modification mechanism of PMB. Afterwards, polymer molecular model with a polymerization degree over 2000 is constructed and dynamic simulation is conducted to reveal the mesoscopic mechanism of SBS polymer’s entropy elasticity. As for macroscopic evaluation, a series of creep and recovery tests associated with different testing temperatures (10 °C to 100 °C with a 6 °C gap), recovery times (0.01 s, 0.1 s, 1 s, 4 s and 9 s) and SBS dosages (0 %, 2.5 %, 4.2 %, 7.5 %) were carried out to characterize the elasticity of various PMBs. The results show that plain bitumen mainly shows energy-elasticity, which is small, instantaneous and highly temperature-dependent, while PMB mainly shows entropy-elasticity, which is strong, delayed and less temperature-dependent. Under the condition of low temperature and short recovery time, the bitumen molecules freeze and prevent the SBS polymer to demonstrate its entropy-elasticity, hence the energy-elasticity dominates. Higher temperatures and long recovery time render the SBS molecule more time to relax and thus the entropy-elasticity dominates. The predominant influence of entropy-elasticity in PMA leads to a unique increasing recovery rate within a specific high-temperature range. This phenomenon can be utilized as a fingerprint approach for the identification of the entropy-elasticity and polymer modification.

Room Temperature Ammonia (NH3) Gas Sensor based on Molybdenum Disulfide and Reduced Graphene Oxide (MoS2/rGO) Heterojunction.

Nanocomposites based on 2D materials exhibit synergistic behavior at their interfaces, making them a promising candidate for gas sensing applications. The MoS2/rGO nanocomposite used in this study was synthesized using a one-step hydrothermal process. By using X-ray diffraction (XRD), the synthesized composite was thoroughly characterized. The spin coater was used to deposit the nanomaterial thin film onto the glass substrate. The nanocomposite sensing was tested at a 40 ppm concentration of ammonia gas. An increase in ammonia concentration was found to correspond with a rise in the resistance of the sensor. The nanocomposite interface of this sensor enabled it to exhibit a synergistic behavior, resulting in several desirable characteristics, including low power consumption, fast response and recovery times, high selectivity, and a low operating temperature.

Pd doped Janus HfSeS monolayer: Ultrahigh sensitive gas sensing material for reversible detection of NO

Recent studies on two-dimensional (2D) Janus transition metal dichalcogenides (TMDs) show that these materials have excellent electronic property and raised very promising prospects for applying them as gas sensor materials. Here we consider the potential application of replacement doping with Pd on the monolayer HfSeS as well as its pristine structure as gas sensor materials for detecting CO, CO2, NH3 and NO through first principles calculations. The calculated results of Ab initio molecule dynamics (AIMD) simulations as well as phonon spectrum which shows no negative frequencies confirmed the good thermodynamical stability of pristine and doped HfSeS. The formation energies of the doped structures with S and Se atoms substituted by Pd atom are − 5.174 and − 5.168 eV which further proves the stability of the structures. The pristine HfSeS cannot well distinguish these four gas molecules due to very close adsorption energies (range from −0.142 eV to −0.477 eV). However, after the introduction of Pd, the doped structure could effectively achieve the distinguish of these four gas molecules (with adsorption energy ranges from −0.229 eV to −0.933 eV). Furthermore, the recovery time of these gases is within 500 s, which shows that the adsorption is reversible both in pristine and Pd-doped monolayer HfSeS. Most interestingly, Pd-doped monolayer HfSeS exhibits ultrahigh sensitive to NO, as the systems become metallic after NO adsorption. Due to the change in conductivity, enhanced adsorption energy, and together with a relatively lower recovery time, Pd-doped monolayer HfSeS exhibits promising application as gas sensors for reversible detection of NO.

High efficiency toluene sensor based on iron-doped nickel oxide triple-shell microspheres with high moisture resistance

This paper provides a simple one-step synthesis of Fe-doped NiO triple-shell layer microsphere structures for toluene gas detection. The 2 at% Fe-doped NiO sensor has excellent sensing ability for toluene gas, with high response (36–100 ppm), low detection limits (100 ppb), fast response and recovery time (2/20 s). Moreover, the sensor demonstrates excellent moisture resistance, with satisfactory response to toluene even in conditions of 99 % relative humidity (34.1–100 ppm). To further investigate the adsorption properties of the sensor, a density functional theory (DFT) approach was employed, and the sensing mechanism of the NiO sensor was discussed detailly. Analysis of the results suggests that Fe-doped NiO triple-shell layer microspheres represent a promising approach for the design of high-performance toluene gas sensors.

MEMS-based electronic nose system for measurement of industrial gases with drift correction methodology

This work explores the use of microelectromechanical system (MEMS) sensors in electronic nose systems for the measurement of prominent industrial pollutants and proposes a methodology for the correction of drift induced in sensors during prolonged use for measurement of corrosive compounds. MEMS sensors have the advantages of low recovery and response time, lower power consumption and improved sensitivity. An electronic nose system is developed to quantify the four major pollutants emitted from various process industries, i.e. hydrogen sulfide (H2S), carbon monoxide (CO), ammonia (NH3) and ethanol (C2H5OH). All four pollutants represent major environmental and human health hazards and rapid quantification is vital. A drift correction algorithm was developed using experimental design and robust regression to correct the drift induced in the sensors. The experiments consisted of eight experimental sets with mixtures of H2S, CO, NH3 and C2H5OH measured on the same sensor array at the start and after a gap of 1 year. The methodology consisted of mapping the response of sensors after 1 year compared with that observed at the very start (day 1) of the experiment. The results showed successful implementation of the methodology, with the root mean square error values being significantly reduced at 0.235, 0.354, 0.145 and 0.651, respectively, for the four studied odorants (H2S, NH3, CO, and C2H5OH).

Room temperature NH3 gas sensor based on PMMA/RGO/ZnO nanocomposite films fabricated by in-situ solution polymerization

Effective detection of ammonia gas is of great importance due to its detrimental effects on human health, environment, and ecosystem. High-performance composite gas sensors are vital in accomplishing this goal. Herein, we investigate the performance of an ammonia (NH3) gas sensor fabricated via dip-coating the silver interdigitated electrode for PMMA/RGO/ZnO (PRZ) nanocomposite solution with acetone as a solvent. The PRZ ternary nanocomposite was synthesized using the in-situ solution polymerization method and the resistive properties of the films assembled on the interdigitated electrode were analyzed, with respect to the fixed and varying ammonia gas concentrations, using LCR meter. When the sensor is operated in the controlled chamber containing ammonia gas at room temperature, the sensor responds rapidly to ammonia with a fast recovery of 13.02 s at a gas concentration of 350 ppm. The PRZ sensor exhibits high sensing percentage response (527%), excellent repeatability (four times), high sensitivity at low concentrations (less than 10 ppm), swift response and recovery times (1.94 s/13.02 s), and long-term stability (up to 90 days) with fluctuation of 3.2%, which signifies PRZ composite as a potential material for ammonia gas sensor. Aspects such as simplicity of the synthesis process and fabrication, excellent sensing performance, as well as fast response-recovery time at a particular gas concentration are noteworthy in this study. These features can be utilized for the detection of ammonia gas in chemical and biological fields.