The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temp...The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temperatures.The nanoporous thin films were prepared by sol-gel technique.It was found that the impedance of the sensor sintered at 600 oC changed more than four order of magnitude in the relative humidity（RH） range of 11%-95% at 25 oC.The response and recovery time of the sensor were about 13 and 17 s,respectively.The sensor showed high humidity sensitivity,rapid response and recovery,prominent stability,good repeatability and narrow hysteresis loop.These re-sults indicated that Ce-doped nanoporous ZnO thin films can be used in fabricating high-performance humidity sensors.展开更多
The humidity sensing properties of La^3＋ and K^＋ co-doped Ti0.9Sn0.1O2 thin films were investigated. The humidity sensitive thin films were prepared by sol-gel method on alumina substrates. The sensing behaviors of ...The humidity sensing properties of La^3＋ and K^＋ co-doped Ti0.9Sn0.1O2 thin films were investigated. The humidity sensitive thin films were prepared by sol-gel method on alumina substrates. The sensing behaviors of thin films were inspected at different sintering temperatures by constructing a humidity-impedance measuring system. It was found that the addition of rare earth ion La^3＋ and alkali ion K^＋ was beneficial for improving the humidity sensitive properties of the samples and La0.003K0.5Ti0.9Sn0.1O2 sintered at 500 ℃ for 4 h showed the best humidity sensing properties. The impedance of this thin film decreased from 109 to 104 Ω with excellent linearity in the humidity range of 11%-95%. Narrow hysteresis loop, prominent stability and high sensitivity were obtained. The effects of dopant con-tent and doping mechanism on humidity sensitivity were also discussed in terms of segregation of rare earth ions at grain boundaries and granularity of crystalline and influence of K^＋ on the decrease in the intrinsic resistance of the materials, and increase in the number of wa-ter adsorption sites.展开更多
The humidity sensing properties of La3+/Ce3+-doped TiO2-20 wt.%SnO2 thin films were studied.Sol-gel method was employed to prepare the films on alumina substrates.By constructing a humidity-impedance measuring system,...The humidity sensing properties of La3+/Ce3+-doped TiO2-20 wt.%SnO2 thin films were studied.Sol-gel method was employed to prepare the films on alumina substrates.By constructing a humidity-impedance measuring system,the sensing behaviors were inspected for the films sintered at different temperatures.Experimental results showed that,0.5 wt.% of La2O3 or Ce2O3 doped films sintered at 500 °C for 2 h had the best humidity sensing properties,the impedance decreasing from 109 ? to below 104 ? in the humidity ra...展开更多
In the present work,ferrite(Fe)doped TiO_(2)thin films with different volume percentage(vol%)were synthesized using a spray pyrolysis technique.The effect of Fe doping on structural properties such as crystallite size...In the present work,ferrite(Fe)doped TiO_(2)thin films with different volume percentage(vol%)were synthesized using a spray pyrolysis technique.The effect of Fe doping on structural properties such as crystallite size,texture coefficient,microstrain,dislocation densities etc.were evaluated from the X ray diffratometry(XRD)data.XRD data revealed a polycrystalline anatase TiO_(2)phase for sample synthesized up to 2 vol%and mixed anatase and rutile crystalline phase for sample synthesized at 4 vol%Fe doped TiO_(2).The crystalline size was observed to decrease with increase in Fe dopant vol%and also other structural parameters changes with Fe dopant percentage.In the present work,electrical resistance was observed to decrease with a rise in Fe dopant vol%and temperature of the sample.Thermal properties like temperature coefficient of resistance and activation energy also showed strong correlation with Fe dopant vol%.Humidity sensing properties of the synthesized sample altered with a change in Fe dopant vol%.In the present paper,maximum sensitivity of about 88.7%for the sample synthesized with 2 vol%Fe doped TiO_(2)and also the lowest response and recovery time of about 52 and 3 s were reported for the same sample.展开更多
A γ - type of layered zirconium hydrogen phosphate, Zr(HPO 4) 2·2H 2O( γ ZrP), was synthesized under hydrothermal conditions and characterized by powder X ray diffraction and thermogravimetric analysis....A γ - type of layered zirconium hydrogen phosphate, Zr(HPO 4) 2·2H 2O( γ ZrP), was synthesized under hydrothermal conditions and characterized by powder X ray diffraction and thermogravimetric analysis. The temperature dependence of the proton conductivity in γ ZrP was investigated in a temperature range of 23￣413 ℃ by ac impedance spectroscopy. The variation of the conductivity with water loss and phase transitions was observed. The best proton conductivity in γ ZrP is 6×10 -4 S·cm -1 at 60 ℃. The proton conductivities in the dehydrated sample are ￣10 -5 at 150 ℃ and ￣10 -4 S·cm -1 at 350 ℃, respectively. The conductivities as a function of humidity in the temperature range of 120￣200 ℃ were measured.展开更多
In this letter,a humidity sensor is demonstrated by applying a whispering gallery mode(WGM)from a microsphere resonator onto the ZnO nanorods coated glass surface.The diameter of the microsphere was 234μm and the gla...In this letter,a humidity sensor is demonstrated by applying a whispering gallery mode(WGM)from a microsphere resonator onto the ZnO nanorods coated glass surface.The diameter of the microsphere was 234μm and the glass surface was coated with ZnO nanorods using the hydrothermal method at growth duration of 12 h.A significant response to humidity level ranging from 35%RH to 85%RH has been observed with the sensitivity of 0.0142 nm/%RH.The proposed humidity sensor has successfully employed to enhance interaction between the whispering gallery mode evanescent and surrounds analyte with the assistance of ZnO nanorods coated glass.展开更多
The growing demand for personalized health care,smart wearables,and advanced environmental monitoring has spurred the development of multifunctional materials that combine flexibility,environmental adaptability,and di...The growing demand for personalized health care,smart wearables,and advanced environmental monitoring has spurred the development of multifunctional materials that combine flexibility,environmental adaptability,and diverse functionalities.However,conventional materials often failed to integrate these attributes simultaneously,hindering their applicability in next-generation technologies.Here,we present an organic-inorganic hybrid crystalline material with a unique sandwich-like architecture,in which a flexible organic crystal core is encased by reduced graphene oxide(rGO)and thermoplastic polyurethane(TPU).This strategic integration endows the material with fluorescence,cryogenic flexibility,and electrical conductivity,while also enabling dual sensing and actuation capabilities.The rGO layer facilitates real-time humidity(25-90%RH)and temperature(25-180℃)sensing through environmental interactions,whereas the differential thermal expansion between TPU and the flexible crystal core drives efficient photothermal actuation at-150℃for advanced thermal regulation.The hybrid material exhibits stable performance under extreme conditions,making it a promising candidate for biomedical monitoring,flexible electronics,and energy applications.This work establishes hybrid crystalline materials as versatile and scalable platforms for addressing complex technological demands,paving the way for their application in next-generation multifunctional devices.展开更多
An intelligent humidity sensing system has been developed for real-time monitoring of human behaviors through respiration detection.The key component of this system is a humidity sensor that integrates a thermistor an...An intelligent humidity sensing system has been developed for real-time monitoring of human behaviors through respiration detection.The key component of this system is a humidity sensor that integrates a thermistor and a micro-heater.This sensor employs porous nanoforests as its sensing material,achieving a sensitivity of 0.56 pF/%RH within a range of 60–90%RH,along with excellent long-term stability and superior gas selectivity.The micro-heater in the device provides a high operating temperature,enhancing sensitivity by 5.8 times.This significant improvement enables the capture of weak humidity variations in exhaled gases,while the thermistor continuously monitors the sensor’s temperature during use and provides crucial temperature information related to respiration.With the assistance of a machine learning algorithm,a behavior recognition system based on the humidity sensor has been constructed,enabling behavior states to be classified and identified with an accuracy of up to 96.2%.This simple yet intelligent method holds great potential for widespread applications in medical assistance analysis and daily health monitoring.展开更多
A fiber-optic humidity sensor has been fabricated by coating a moisture sensitive polymer film to the fiber Bragg grating （FBG）. The Bragg wavelength of the polyimide-coated FBG changes while it is exposed to differ...A fiber-optic humidity sensor has been fabricated by coating a moisture sensitive polymer film to the fiber Bragg grating （FBG）. The Bragg wavelength of the polyimide-coated FBG changes while it is exposed to different humidity conditions due to the volume expansion of the polyimide coating. The characteristics of sensors, including sensitivity, temporal response, and hysteresis, were improved by controlling the coating thickness and the degree of imidization during the thermal curing process of the polyimide. In the relative humidity （RH） condition ranging from 11.3%RH to 97.3%RH, the sensitivity of the sensor was about 13.5pm/%RH with measurement uncertainty of ±1.5%RH.展开更多
Traditional ionic liquids are sensitive to humidity but with long response time and nonlinear response.Pure liquid-state ionic liquids are usually hard for dehydration which have ultralong response time for humidity s...Traditional ionic liquids are sensitive to humidity but with long response time and nonlinear response.Pure liquid-state ionic liquids are usually hard for dehydration which have ultralong response time for humidity sensing.The immobilization of ionic liquids provide a possible way for high performance humidity sensing.Hydrophobic materials and structures also promised faster response in humidity sensing,because of easier desorption of water.In this work,we prepared flexible humidity sensitive composites based on hydrophobic ionic liquid and polymer.The combination of hydrophobic ionic liquid with hydrophobic polymer realized linear response,high sensitivity with low hysteresis to humidity.By adjusting the ratio of ionic liquid,not only the impedance but also the hydrophobicity of composite could be modulated,which had a significant influence on the humidity sensing performance.The morphology and microstructure of the material also affected its interaction with water molecules.Due to the diverse processing methods of polymer,highly transparent film fabricated by spinning-coating and nanofibrous membrane fabricated by electrospinning could be prepared and exhibited different response time,which could be used for different application scenarios.Especially,the fibrous membrane made with electrospinning method showed an ultrafast response and could distinguish up to 120 Hz humidity change,due to its fibrous structure with high specific surface area.The humidity sensors with ultrafast,linear response and high sensitivity showed potential applications in human respiratory monitoring and flexible non-contact switch.To better show the multifunction of ionic liquid-polymer composite,as a proof of concept,we fabricated an integrated humidity sensitive color change device by utilizing lower ionic liquid content composite for sensing in the humidity sensing module and higher ionic liquid content composite as the electrolyte in the electrochromic module.展开更多
Microlasers based on high quality(Q)whispering-gallery mode(WGM)resonance are pronfising low threshold laser sources for bio-sensing and imaging applications.In this Letter,dye-doped polymer microspheres were fabricat...Microlasers based on high quality(Q)whispering-gallery mode(WGM)resonance are pronfising low threshold laser sources for bio-sensing and imaging applications.In this Letter,dye-doped polymer microspheres were fabricated by a controlling emulsion solvent evaporation method.WGM lasing with low threshold and high Q factors was realized in an individual microsphere under femtosecond laser pumping.The slight change of environmental relative humidity(RH)can be monitored by measuring the shift of the lasing modes at tile ex-posure of water molecules,which dcmonstrates the sensitivity is as high as 6 pm/RH%.The results would offer an insight into employing microlasers as sensors.展开更多
A series of aluminium-containing α-type hydrated zirconium hydrogen phosphates,Zr_(1-x)Alx (H_(1+x/2)PO_4 )_2 with x=0-0.06,were hydrothermally synthesized and characterizedby means of X-ray diffraction,differential ...A series of aluminium-containing α-type hydrated zirconium hydrogen phosphates,Zr_(1-x)Alx (H_(1+x/2)PO_4 )_2 with x=0-0.06,were hydrothermally synthesized and characterizedby means of X-ray diffraction,differential thermal analysis and thermogravimetric analysis.The proton conductivity,1.2×10￣(-4) S·cm￣(-1)at 180℃ was found in Zr_(0.98)Al_(0.02)(H_(1.01)PO_4)_2·H_2O.Humidity-sensing measurements were carried out at 120℃ and 140℃ respectively.Even a limited substitution of Al for Zr can enhance both proton conductivity and humidity sensitivity.展开更多
The angle dependence of photonic crystals(PCs)dramatically limits their practical applications in the colorimetrical sensing of humidity and volatile organic compound(VOC)vapors.In addition,it is challenging for inver...The angle dependence of photonic crystals(PCs)dramatically limits their practical applications in the colorimetrical sensing of humidity and volatile organic compound(VOC)vapors.In addition,it is challenging for inverse opal PCs to colorimetrically distinguish between vapors with similar refractive indices.Different from the mechanism of PC-based sensors,here,we report an angle-independent polyacrylamide(PAAm)organogel structural color film based on the mechanisms of retroreflection,total internal reflection(TIR)and interference with a shape similar to a single-sided“egg waffle”.During the process of responding to humidity and VOC vapors,the color of the film remains angle-independent in the normal angle range of 0°to 45°under coaxial illumination and observation conditions.At the same time,the film can colorimetrically distinguish between vapors with similar refractive indices,such as methanol and ethanol,which is mainly due to the differences in their polarity and solubility parameters.The film shows good stability,reversibility and selectivity when exposed to vapors.A colorimetric sensor with a new response mechanism is proposed and has the potential to effectively distinguish between vapors with similar refractive indices.Furthermore,this responsive retroreflective structural color film(RRSCF)provides a universal strategy to develop targeted angle-independent structural color sensors by selecting optimized materials.展开更多
Vanadium doped nanoporous Ti0.9Sn0.1O2 thin film has been prepared on an alumina substrate by sol-gel method with Pluronic P123 as the organic template, and humidity sensing properties of it has been investigated. It ...Vanadium doped nanoporous Ti0.9Sn0.1O2 thin film has been prepared on an alumina substrate by sol-gel method with Pluronic P123 as the organic template, and humidity sensing properties of it has been investigated. It is found that V-doped nanoporous Ti0.9Sn0.1O2 thin film shows good humidity sensing properties, and impendence of it de- creases more than four orders of magnitude in the relative humidity （RH） range of 11%--95% at 25 ℃. The response and recovery time of this sensor are about 13 and 17 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good repeatability are obtained. A possible mechanism is sug- gested to explain the humidity sensitive properties.展开更多
Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity ...Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity sensing properties of Cu-Mg-Zn ferrites with rare earth element doping were investigated.Single-phase cubic spinel structure was confirmed via X-ray diffraction(XRD),and the crystal size ranges fro m 22.12 to 63.17 nm according to the Scherrer formula and from 25.66 to 67.46 nm according to the Williamson-Hall method.Po rous structure and elemental characterization of the samples were investigated by scanning electron microscopy(SEM).The optic band gap varies between 2.21 and 2.49 eV.Electrical measurements were conducted in the frequency range of 1 Hz-20 MHz and temperature range of 25-400℃.It has been determined that the dielectric results are consistent with the Maxwell-Wagner method and exhibit a non-Debye relaxation model,as observed from the Nyquist plots.At a minimum frequency value of 1 Hz,the dielectric constants for pure,Ce,Sr,and La samples are 9×10^(4),5×10^(4),1×10^(8),and 2×10^(5) at 25℃,and 1.85×10^(8),1.34×10^(8),1.15×10^(10),and 4.4×10^(8)at 400℃.In the same order,for the maximum frequency value of 20 MHz,the dielectric constants at 25℃are 169,166,3799,and 60,while at 400℃they are 734,624,12108,and 774.The La doped sample's low dielectric loss makes it suitable for high-frequency applications.Humidity measurements were performed at room temperature and in the 5%-95%relative humidity range.The humidity properties of the samples were investigated through humidity mapping,sensitivity,hysteresis,and long-term stability tests.Compared to other samples,the results indicate that Ce exhibits better humidity performance with 99%sensitivity and the highest repeatability(91.2%).These results show that Ce-doped ferrite can be used as a low-cost,high-performance humidity sensor.展开更多
Most resistance-type humidity sensors exhibit negative humidity sensitivity,i.e.,their resistance decreases with a corresponding increase in humidity.This is primarily attributed to the dominant role of ionic conducti...Most resistance-type humidity sensors exhibit negative humidity sensitivity,i.e.,their resistance decreases with a corresponding increase in humidity.This is primarily attributed to the dominant role of ionic conduction in adsorbed water.In this work,a humidity sensor based on a p-type reduced graphene oxide(p-rGO)with positive humidity sensitivity is proposed.Moreover,its positive humidity sensing response is further enhanced by n-type WS_(2) nanoparticles modification.The results show that both rGO and r GO/WS_(2) humidity sensors have good linear response in the relative humidity(RH)range of0%-91.5%.The sensitivity of the rGO/WS_(2) humidity sensor is 1.87 times that of rGO humidity sensor,which is mainly attributed to p-n heterojunction between rGO and WS_(2).Besides,the r GO/WS_(2) humidity sensor has small humidity hysteresis(-3%RH)and good repeatability.This work demonstrates a humidity sensor based on rGO/WS_(2) composite film and provides a facile route for fabricating humidity sensor with positive humidity sensing properties.展开更多
Capacitive humidity sensors were made of nanometer barium titanate.The pellets were prepared under different pressures between 3920N to 7850N force.The capacitance changes in three orders of magnitude in the relative ...Capacitive humidity sensors were made of nanometer barium titanate.The pellets were prepared under different pressures between 3920N to 7850N force.The capacitance changes in three orders of magnitude in the relative humidity range of 10%～98%,indicating high humidity sensitivity of the sensors.At a certain measuring frequency,the capacitance of the sensors increases as increasing of the preparation pressure,while the sensitivity of the sensors basically remains the same.The frequencies corresponding to the peaks of the dielectric loss of the sensors move to the higher frequency direction as increasing of the relative humidity.At a certain humidity,the frequencies corresponding to the peaks of the dielectric loss move to the higher frequency direction as increasing of the preparation pressure.展开更多
Porous materials used for humidity sensing have been commercialized.In this paper,the preparation and humidity sensing characteristics of porous silicon with P-N junctions (PNJPS)are studied.PNJPS is made by electro-c...Porous materials used for humidity sensing have been commercialized.In this paper,the preparation and humidity sensing characteristics of porous silicon with P-N junctions (PNJPS)are studied.PNJPS is made by electro-chemical anodic etched method from silicon wafers with P-N junctions.Its porous structure is verified by scanning electronic micrograph. Experiments also show that PNJPS has high sensitivity,short response time (less than 30 seconds),and long-term stability.展开更多
Flexible optical sensing systems have evolved into a promising frontier for personalized health monitoring,leveraging their non-invasive operation and continuous data acquisition.Nevertheless,current optical solutions...Flexible optical sensing systems have evolved into a promising frontier for personalized health monitoring,leveraging their non-invasive operation and continuous data acquisition.Nevertheless,current optical solutions remain constrained by limitations in detection sensitivity and specificity,hindering their reliability in dynamic clinical environments.Herein,we propose a design of flexible semiinterpenetrating network hydrogel lasing textiles for multifunctional sensing,including relative humidity and acid pH detection.By integrating the humidity-responsive swelling and carboxyl protonation-mediated optical loss modulation of hydrogels with whispering-gallery-mode microcavity lasers,we achieve a dual-parameter flexible optical sensing based on wavelength shift and spectral linewidth modulation,enabling a 227 pm/%RH sensitivity of humidity detection and 125 pm/pH sensitivity of acid pH monitoring,with limit of detection of 0.71%RH and 0.55 pH,respectively.This work is expected to establish new pathways for non-invasive health monitoring in flexible systems.展开更多
Multifunctional materials have attracted tremendous attention in intelligent and interactive devices.However,achieving multi-dimensional sensing capabilities with the same perovskite quantum dot(PQD)material is still ...Multifunctional materials have attracted tremendous attention in intelligent and interactive devices.However,achieving multi-dimensional sensing capabilities with the same perovskite quantum dot(PQD)material is still in its infancy,with some considering it currently challenging and even unattainable.Drawing inspiration from neurons,a novel multifunctional CsPbBr_(3)/PDMS nanosphere is devised to sense humidity,temperature,and pressure simultaneously with unique interactive responses.The carefully engineered polydimethylsiloxane(PDMS)shell enables the reversible activity of the core CsPbBr_(3),serving a dual role similar to dendrites in conveying and evaluating external stimuli with high sensitivity.Molecular dynamics analysis reveals that the PDMS shell with proper pore density enhances the conductivity in water and heat,imparting CsPbBrs with sensitive but reversible properties.By tailoring the crosslinking density of the PDMS shell,nanospheres can surprisingly show customized sensitivity and reversible responses to different level of stimuli,achieving over 95%accuracy in multi-dimensional and wide-range sensing.The regular pressure-sensitive property,discovered for the frst time,is attributed to the regular morphology of the nanosphere,the inherent low rigidity of the PDMS shell,and the uniform distribution of the CsPbBr core material in combination.This study breaks away from conventional design paradigms of perovskite core-shell materials by customizing the cross-linked density of the shell material.The reversible response mechanism of nanospheres with gradient shell density is deeply explored in response to environmental stimuli,which offers fresh insights into multi-dimensional sensing and interactive display applications.展开更多
文摘The humidity sensitive characteristics of the sensor fabricated from Ce-doped nanoporous ZnO by screen-printing on the alumina substrate with Ag-Pd interdigital electrodes were investigated at different sintering temperatures.The nanoporous thin films were prepared by sol-gel technique.It was found that the impedance of the sensor sintered at 600 oC changed more than four order of magnitude in the relative humidity（RH） range of 11%-95% at 25 oC.The response and recovery time of the sensor were about 13 and 17 s,respectively.The sensor showed high humidity sensitivity,rapid response and recovery,prominent stability,good repeatability and narrow hysteresis loop.These re-sults indicated that Ce-doped nanoporous ZnO thin films can be used in fabricating high-performance humidity sensors.
文摘The humidity sensing properties of La^3＋ and K^＋ co-doped Ti0.9Sn0.1O2 thin films were investigated. The humidity sensitive thin films were prepared by sol-gel method on alumina substrates. The sensing behaviors of thin films were inspected at different sintering temperatures by constructing a humidity-impedance measuring system. It was found that the addition of rare earth ion La^3＋ and alkali ion K^＋ was beneficial for improving the humidity sensitive properties of the samples and La0.003K0.5Ti0.9Sn0.1O2 sintered at 500 ℃ for 4 h showed the best humidity sensing properties. The impedance of this thin film decreased from 109 to 104 Ω with excellent linearity in the humidity range of 11%-95%. Narrow hysteresis loop, prominent stability and high sensitivity were obtained. The effects of dopant con-tent and doping mechanism on humidity sensitivity were also discussed in terms of segregation of rare earth ions at grain boundaries and granularity of crystalline and influence of K^＋ on the decrease in the intrinsic resistance of the materials, and increase in the number of wa-ter adsorption sites.
基金supported by the Natioanl Natural Science Foundation of China (50562003)
文摘The humidity sensing properties of La3+/Ce3+-doped TiO2-20 wt.%SnO2 thin films were studied.Sol-gel method was employed to prepare the films on alumina substrates.By constructing a humidity-impedance measuring system,the sensing behaviors were inspected for the films sintered at different temperatures.Experimental results showed that,0.5 wt.% of La2O3 or Ce2O3 doped films sintered at 500 °C for 2 h had the best humidity sensing properties,the impedance decreasing from 109 ? to below 104 ? in the humidity ra...
文摘In the present work,ferrite(Fe)doped TiO_(2)thin films with different volume percentage(vol%)were synthesized using a spray pyrolysis technique.The effect of Fe doping on structural properties such as crystallite size,texture coefficient,microstrain,dislocation densities etc.were evaluated from the X ray diffratometry(XRD)data.XRD data revealed a polycrystalline anatase TiO_(2)phase for sample synthesized up to 2 vol%and mixed anatase and rutile crystalline phase for sample synthesized at 4 vol%Fe doped TiO_(2).The crystalline size was observed to decrease with increase in Fe dopant vol%and also other structural parameters changes with Fe dopant percentage.In the present work,electrical resistance was observed to decrease with a rise in Fe dopant vol%and temperature of the sample.Thermal properties like temperature coefficient of resistance and activation energy also showed strong correlation with Fe dopant vol%.Humidity sensing properties of the synthesized sample altered with a change in Fe dopant vol%.In the present paper,maximum sensitivity of about 88.7%for the sample synthesized with 2 vol%Fe doped TiO_(2)and also the lowest response and recovery time of about 52 and 3 s were reported for the same sample.
文摘A γ - type of layered zirconium hydrogen phosphate, Zr(HPO 4) 2·2H 2O( γ ZrP), was synthesized under hydrothermal conditions and characterized by powder X ray diffraction and thermogravimetric analysis. The temperature dependence of the proton conductivity in γ ZrP was investigated in a temperature range of 23￣413 ℃ by ac impedance spectroscopy. The variation of the conductivity with water loss and phase transitions was observed. The best proton conductivity in γ ZrP is 6×10 -4 S·cm -1 at 60 ℃. The proton conductivities in the dehydrated sample are ￣10 -5 at 150 ℃ and ￣10 -4 S·cm -1 at 350 ℃, respectively. The conductivities as a function of humidity in the temperature range of 120￣200 ℃ were measured.
基金supported by the National Natural Science Foundation of China(Nos.U1304608 and 61774053)the Project of Henan Provincial Department of Science and Technology(No.182102410047)the Program of Henan Polytechnic University(No.B2014-020)。
文摘In this letter,a humidity sensor is demonstrated by applying a whispering gallery mode(WGM)from a microsphere resonator onto the ZnO nanorods coated glass surface.The diameter of the microsphere was 234μm and the glass surface was coated with ZnO nanorods using the hydrothermal method at growth duration of 12 h.A significant response to humidity level ranging from 35%RH to 85%RH has been observed with the sensitivity of 0.0142 nm/%RH.The proposed humidity sensor has successfully employed to enhance interaction between the whispering gallery mode evanescent and surrounds analyte with the assistance of ZnO nanorods coated glass.
基金support from the National Natural Science Foundation of China(52373181 and 52173164)the Natural Science Foundation of Jilin Province(20250102120JC and 20230101038JC)+1 种基金the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(GZB20240259)the Project funded by China Postdoctoral Science Foundation(2024M761121 and 2025T180139).
文摘The growing demand for personalized health care,smart wearables,and advanced environmental monitoring has spurred the development of multifunctional materials that combine flexibility,environmental adaptability,and diverse functionalities.However,conventional materials often failed to integrate these attributes simultaneously,hindering their applicability in next-generation technologies.Here,we present an organic-inorganic hybrid crystalline material with a unique sandwich-like architecture,in which a flexible organic crystal core is encased by reduced graphene oxide(rGO)and thermoplastic polyurethane(TPU).This strategic integration endows the material with fluorescence,cryogenic flexibility,and electrical conductivity,while also enabling dual sensing and actuation capabilities.The rGO layer facilitates real-time humidity(25-90%RH)and temperature(25-180℃)sensing through environmental interactions,whereas the differential thermal expansion between TPU and the flexible crystal core drives efficient photothermal actuation at-150℃for advanced thermal regulation.The hybrid material exhibits stable performance under extreme conditions,making it a promising candidate for biomedical monitoring,flexible electronics,and energy applications.This work establishes hybrid crystalline materials as versatile and scalable platforms for addressing complex technological demands,paving the way for their application in next-generation multifunctional devices.
基金supported by National Natural Science Foundation of China(Grant Nos.62474192 and 62201567)Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant Nos.2022048 and 2022117)State Key Laboratory of Dynamic Test jointly built by Province and Ministry Open Fund(Grant No.2022-SYSJJ-07).
文摘An intelligent humidity sensing system has been developed for real-time monitoring of human behaviors through respiration detection.The key component of this system is a humidity sensor that integrates a thermistor and a micro-heater.This sensor employs porous nanoforests as its sensing material,achieving a sensitivity of 0.56 pF/%RH within a range of 60–90%RH,along with excellent long-term stability and superior gas selectivity.The micro-heater in the device provides a high operating temperature,enhancing sensitivity by 5.8 times.This significant improvement enables the capture of weak humidity variations in exhaled gases,while the thermistor continuously monitors the sensor’s temperature during use and provides crucial temperature information related to respiration.With the assistance of a machine learning algorithm,a behavior recognition system based on the humidity sensor has been constructed,enabling behavior states to be classified and identified with an accuracy of up to 96.2%.This simple yet intelligent method holds great potential for widespread applications in medical assistance analysis and daily health monitoring.
基金This work is supported by National Natural Science Foundation of China （61107073, 61107072 and 61290312）, Fundamental Research Funds for the Central Universities （ZYGX2011J002）, Research Fund for the Doctoral Program of Higher Education of China （20110185120020）, Program for Changjiang Scholars and Innovative Research Team in University （PCSIRT, IRT1218）, and the 111 Project （B 14039）.
文摘A fiber-optic humidity sensor has been fabricated by coating a moisture sensitive polymer film to the fiber Bragg grating （FBG）. The Bragg wavelength of the polyimide-coated FBG changes while it is exposed to different humidity conditions due to the volume expansion of the polyimide coating. The characteristics of sensors, including sensitivity, temporal response, and hysteresis, were improved by controlling the coating thickness and the degree of imidization during the thermal curing process of the polyimide. In the relative humidity （RH） condition ranging from 11.3%RH to 97.3%RH, the sensitivity of the sensor was about 13.5pm/%RH with measurement uncertainty of ±1.5%RH.
基金the National Key Research and Development Program of China(No.2017YFB1104300)the National Natural Science Foundation of China(No.51672150).
文摘Traditional ionic liquids are sensitive to humidity but with long response time and nonlinear response.Pure liquid-state ionic liquids are usually hard for dehydration which have ultralong response time for humidity sensing.The immobilization of ionic liquids provide a possible way for high performance humidity sensing.Hydrophobic materials and structures also promised faster response in humidity sensing,because of easier desorption of water.In this work,we prepared flexible humidity sensitive composites based on hydrophobic ionic liquid and polymer.The combination of hydrophobic ionic liquid with hydrophobic polymer realized linear response,high sensitivity with low hysteresis to humidity.By adjusting the ratio of ionic liquid,not only the impedance but also the hydrophobicity of composite could be modulated,which had a significant influence on the humidity sensing performance.The morphology and microstructure of the material also affected its interaction with water molecules.Due to the diverse processing methods of polymer,highly transparent film fabricated by spinning-coating and nanofibrous membrane fabricated by electrospinning could be prepared and exhibited different response time,which could be used for different application scenarios.Especially,the fibrous membrane made with electrospinning method showed an ultrafast response and could distinguish up to 120 Hz humidity change,due to its fibrous structure with high specific surface area.The humidity sensors with ultrafast,linear response and high sensitivity showed potential applications in human respiratory monitoring and flexible non-contact switch.To better show the multifunction of ionic liquid-polymer composite,as a proof of concept,we fabricated an integrated humidity sensitive color change device by utilizing lower ionic liquid content composite for sensing in the humidity sensing module and higher ionic liquid content composite as the electrolyte in the electrochromic module.
基金supported by the National Natural Science Foundation of China(NSFC)(No.61275054)the Science and Technology Support Program of Jiangsu Province(No.BE2016177)"Collaborative Innovation Center of Suzhou Nano Science and Technology"for their support
文摘Microlasers based on high quality(Q)whispering-gallery mode(WGM)resonance are pronfising low threshold laser sources for bio-sensing and imaging applications.In this Letter,dye-doped polymer microspheres were fabricated by a controlling emulsion solvent evaporation method.WGM lasing with low threshold and high Q factors was realized in an individual microsphere under femtosecond laser pumping.The slight change of environmental relative humidity(RH)can be monitored by measuring the shift of the lasing modes at tile ex-posure of water molecules,which dcmonstrates the sensitivity is as high as 6 pm/RH%.The results would offer an insight into employing microlasers as sensors.
文摘A series of aluminium-containing α-type hydrated zirconium hydrogen phosphates,Zr_(1-x)Alx (H_(1+x/2)PO_4 )_2 with x=0-0.06,were hydrothermally synthesized and characterizedby means of X-ray diffraction,differential thermal analysis and thermogravimetric analysis.The proton conductivity,1.2×10￣(-4) S·cm￣(-1)at 180℃ was found in Zr_(0.98)Al_(0.02)(H_(1.01)PO_4)_2·H_2O.Humidity-sensing measurements were carried out at 120℃ and 140℃ respectively.Even a limited substitution of Al for Zr can enhance both proton conductivity and humidity sensitivity.
基金supported by National Key Research and Development Program of China(Nos.2017YFA0204600,2018YFE0201701)National Natural Science Foundation of China(No.51673041).
文摘The angle dependence of photonic crystals(PCs)dramatically limits their practical applications in the colorimetrical sensing of humidity and volatile organic compound(VOC)vapors.In addition,it is challenging for inverse opal PCs to colorimetrically distinguish between vapors with similar refractive indices.Different from the mechanism of PC-based sensors,here,we report an angle-independent polyacrylamide(PAAm)organogel structural color film based on the mechanisms of retroreflection,total internal reflection(TIR)and interference with a shape similar to a single-sided“egg waffle”.During the process of responding to humidity and VOC vapors,the color of the film remains angle-independent in the normal angle range of 0°to 45°under coaxial illumination and observation conditions.At the same time,the film can colorimetrically distinguish between vapors with similar refractive indices,such as methanol and ethanol,which is mainly due to the differences in their polarity and solubility parameters.The film shows good stability,reversibility and selectivity when exposed to vapors.A colorimetric sensor with a new response mechanism is proposed and has the potential to effectively distinguish between vapors with similar refractive indices.Furthermore,this responsive retroreflective structural color film(RRSCF)provides a universal strategy to develop targeted angle-independent structural color sensors by selecting optimized materials.
文摘Vanadium doped nanoporous Ti0.9Sn0.1O2 thin film has been prepared on an alumina substrate by sol-gel method with Pluronic P123 as the organic template, and humidity sensing properties of it has been investigated. It is found that V-doped nanoporous Ti0.9Sn0.1O2 thin film shows good humidity sensing properties, and impendence of it de- creases more than four orders of magnitude in the relative humidity （RH） range of 11%--95% at 25 ℃. The response and recovery time of this sensor are about 13 and 17 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good repeatability are obtained. A possible mechanism is sug- gested to explain the humidity sensitive properties.
基金supported by the Ondokuz Mayis University Project Number PYO.MUH.1901.21.001。
文摘Rare earth(RE)doped ferrites with the chemical formula Cu_(0.3)Zn_(0.3)Mg_(0.4)T_(x)Fe_(2-x)O_(4)(x=0,0.1;T=La,Ce,Sr)were synthesized by chemical co-precipitation method.The structural,optical,electrical and humidity sensing properties of Cu-Mg-Zn ferrites with rare earth element doping were investigated.Single-phase cubic spinel structure was confirmed via X-ray diffraction(XRD),and the crystal size ranges fro m 22.12 to 63.17 nm according to the Scherrer formula and from 25.66 to 67.46 nm according to the Williamson-Hall method.Po rous structure and elemental characterization of the samples were investigated by scanning electron microscopy(SEM).The optic band gap varies between 2.21 and 2.49 eV.Electrical measurements were conducted in the frequency range of 1 Hz-20 MHz and temperature range of 25-400℃.It has been determined that the dielectric results are consistent with the Maxwell-Wagner method and exhibit a non-Debye relaxation model,as observed from the Nyquist plots.At a minimum frequency value of 1 Hz,the dielectric constants for pure,Ce,Sr,and La samples are 9×10^(4),5×10^(4),1×10^(8),and 2×10^(5) at 25℃,and 1.85×10^(8),1.34×10^(8),1.15×10^(10),and 4.4×10^(8)at 400℃.In the same order,for the maximum frequency value of 20 MHz,the dielectric constants at 25℃are 169,166,3799,and 60,while at 400℃they are 734,624,12108,and 774.The La doped sample's low dielectric loss makes it suitable for high-frequency applications.Humidity measurements were performed at room temperature and in the 5%-95%relative humidity range.The humidity properties of the samples were investigated through humidity mapping,sensitivity,hysteresis,and long-term stability tests.Compared to other samples,the results indicate that Ce exhibits better humidity performance with 99%sensitivity and the highest repeatability(91.2%).These results show that Ce-doped ferrite can be used as a low-cost,high-performance humidity sensor.
基金the National Science Funds for Excellent Young Scholars of China(No.61822106)the National Science Funds for Creative Research Groups of China(No.61421002)the National Natural Science Foundation of China(No.61671115)。
文摘Most resistance-type humidity sensors exhibit negative humidity sensitivity,i.e.,their resistance decreases with a corresponding increase in humidity.This is primarily attributed to the dominant role of ionic conduction in adsorbed water.In this work,a humidity sensor based on a p-type reduced graphene oxide(p-rGO)with positive humidity sensitivity is proposed.Moreover,its positive humidity sensing response is further enhanced by n-type WS_(2) nanoparticles modification.The results show that both rGO and r GO/WS_(2) humidity sensors have good linear response in the relative humidity(RH)range of0%-91.5%.The sensitivity of the rGO/WS_(2) humidity sensor is 1.87 times that of rGO humidity sensor,which is mainly attributed to p-n heterojunction between rGO and WS_(2).Besides,the r GO/WS_(2) humidity sensor has small humidity hysteresis(-3%RH)and good repeatability.This work demonstrates a humidity sensor based on rGO/WS_(2) composite film and provides a facile route for fabricating humidity sensor with positive humidity sensing properties.
基金The project is supported by the National Natural Science Foundation of China （60074031, 60474052）.
文摘Capacitive humidity sensors were made of nanometer barium titanate.The pellets were prepared under different pressures between 3920N to 7850N force.The capacitance changes in three orders of magnitude in the relative humidity range of 10%～98%,indicating high humidity sensitivity of the sensors.At a certain measuring frequency,the capacitance of the sensors increases as increasing of the preparation pressure,while the sensitivity of the sensors basically remains the same.The frequencies corresponding to the peaks of the dielectric loss of the sensors move to the higher frequency direction as increasing of the relative humidity.At a certain humidity,the frequencies corresponding to the peaks of the dielectric loss move to the higher frequency direction as increasing of the preparation pressure.
基金National Natural This work was supported Science Foundation of P. R by the China （Grant number： 69666001）West Glory project of Chinese Academy of Science.
文摘Porous materials used for humidity sensing have been commercialized.In this paper,the preparation and humidity sensing characteristics of porous silicon with P-N junctions (PNJPS)are studied.PNJPS is made by electro-chemical anodic etched method from silicon wafers with P-N junctions.Its porous structure is verified by scanning electronic micrograph. Experiments also show that PNJPS has high sensitivity,short response time (less than 30 seconds),and long-term stability.
基金the Beijing Natural Science Foundation(No.Z180015)the National Natural Science Foundation of China(NSFC)(No.52203252)for financial support.
文摘Flexible optical sensing systems have evolved into a promising frontier for personalized health monitoring,leveraging their non-invasive operation and continuous data acquisition.Nevertheless,current optical solutions remain constrained by limitations in detection sensitivity and specificity,hindering their reliability in dynamic clinical environments.Herein,we propose a design of flexible semiinterpenetrating network hydrogel lasing textiles for multifunctional sensing,including relative humidity and acid pH detection.By integrating the humidity-responsive swelling and carboxyl protonation-mediated optical loss modulation of hydrogels with whispering-gallery-mode microcavity lasers,we achieve a dual-parameter flexible optical sensing based on wavelength shift and spectral linewidth modulation,enabling a 227 pm/%RH sensitivity of humidity detection and 125 pm/pH sensitivity of acid pH monitoring,with limit of detection of 0.71%RH and 0.55 pH,respectively.This work is expected to establish new pathways for non-invasive health monitoring in flexible systems.
基金the support of the National Natural Science Foundation of China(Grant Nos.62175032 and 62104077)Key Science and Technology Project Program of Fujian Province(Grant No.2024HZ022005)+1 种基金Natural Science Foundation for Distinguished Young Scholars of Fujian Province(Grant No.2024J010046)Open Project Program of Wuhan National Laboratory for Optoelectronics(GrantNo.2023WNLOKF011).
文摘Multifunctional materials have attracted tremendous attention in intelligent and interactive devices.However,achieving multi-dimensional sensing capabilities with the same perovskite quantum dot(PQD)material is still in its infancy,with some considering it currently challenging and even unattainable.Drawing inspiration from neurons,a novel multifunctional CsPbBr_(3)/PDMS nanosphere is devised to sense humidity,temperature,and pressure simultaneously with unique interactive responses.The carefully engineered polydimethylsiloxane(PDMS)shell enables the reversible activity of the core CsPbBr_(3),serving a dual role similar to dendrites in conveying and evaluating external stimuli with high sensitivity.Molecular dynamics analysis reveals that the PDMS shell with proper pore density enhances the conductivity in water and heat,imparting CsPbBrs with sensitive but reversible properties.By tailoring the crosslinking density of the PDMS shell,nanospheres can surprisingly show customized sensitivity and reversible responses to different level of stimuli,achieving over 95%accuracy in multi-dimensional and wide-range sensing.The regular pressure-sensitive property,discovered for the frst time,is attributed to the regular morphology of the nanosphere,the inherent low rigidity of the PDMS shell,and the uniform distribution of the CsPbBr core material in combination.This study breaks away from conventional design paradigms of perovskite core-shell materials by customizing the cross-linked density of the shell material.The reversible response mechanism of nanospheres with gradient shell density is deeply explored in response to environmental stimuli,which offers fresh insights into multi-dimensional sensing and interactive display applications.
