scholarly journals Synthesis and Fabrication of Polyvinyl Alcohol Nanofibers Based Capacitive Relative Humidity Sensor

2021 ◽  
Vol 11 (01) ◽  
Author(s):  
Haroon Ur Rashid
Keyword(s):  
Relative Humidity ◽  
Polyvinyl Alcohol ◽  
Humidity Sensor ◽  
Morphological Structure ◽  
Electrospun Nanofibers ◽  
Electrospinning Technique ◽  
Thermogravimetric Analyzer ◽  
Sensing Material ◽  
Heat Treated ◽  
Response And Recovery

  Abstract Capacitive humidity sensor based on Polyvinyl-alcohol (PVA) electrospun nanofibers was fabricated. PVA nanofibers were synthesized through versatile electrospinning technique. The synthesized nanofibers were heat treated and characterized via Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and thermogravimetric Analyzer (TGA) for structural, morphological and thermal properties. The fibers of admirable morphological structure were selected and deposited over interdigitated alumina electrodes for the investigation of Relative Humidity (RH) sensing characteristics. The variation in capacitance of the sensor with RH was measured 48pf at 32-92% RH. The dynamic response study confirmed the durability and stability of the sensor. The material exhibited quick response and recovery time and takes 13.27 seconds to measure the maximum RH value. Thus, the proposed sensing material has the potential of possible application in humidity sensing devices.  

Relative Humidity Sensor Based on Tilted Fiber Bragg Grating With Polyvinyl Alcohol Coating

2009 ◽  
Vol 21 (7) ◽  
pp. 441-443 ◽  
Author(s):  
Yinping Miao ◽  
Bo Liu ◽  
Hao Zhang ◽  
Yuan Li ◽  
Haibin Zhou ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Polyvinyl Alcohol ◽  
Fiber Bragg Grating ◽  
Humidity Sensor ◽  
Bragg Grating ◽  
Relative Humidity Sensor

scholarly journals Evaluation of chemical and physical properties of biodegradable gum Arabic/PVA/Ag nanofibrous membranes as a potential wrapping material

2020 ◽  
Vol 15 ◽  
pp. 155892502094645
Author(s):  
Mayza Ibrahim ◽  
Michal Krejčík ◽  
Karel Havlíček ◽  
Stanislav Petrík ◽  
Mohamed Eldessouki
Keyword(s):  
Polyvinyl Alcohol ◽  
Food Packaging ◽  
Mechanical Performance ◽  
Micrococcus Luteus ◽  
Gum Arabic ◽  
Electrospun Nanofibers ◽  
Longitudinal Direction ◽  
Inhibition Zone ◽  
Electrospinning Technique ◽  
Direction Parallel

There is a growing public interest in utilizing biomass and biomaterials to obtain products with high sustainability and less harm to the environment. This study reports on using electrospinning technique to produce nanofiber membranes based on homogeneous polymeric blends of gum Arabic, polyvinyl alcohol, and silver nanoparticles. The produced interconnected membranes were cross-linked via heat and plasma treatments, and the membranes were characterized for their chemical and physical characteristics. Fourier transform infrared spectroscopy shows a cross-linking of gum Arabic and polyvinyl alcohol through esterification during the heat treatment, and through graft polymerization with methyl groups after methane plasma treatment. The mechanical performance of the membranes showed an increase in the modulus of elasticity in the longitudinal direction (parallel to electrospun nanofibers) from 85 ± 4 MPa to 148 ± 5 MPa compared with the transverse direction. Also, well-dispersed nanoparticles in the spinning solution tend to increase the elasticity from 41 ± 3 MPa to 148 ± 5 MPa, while the agglomeration of these nanoparticles decreases the mechanical properties of the nanofibers. Results of the biodegradation tests confirmed the significant biodegradable nature of the produced nanofibers, where 99.09% of the material was degraded within 28 days. Moreover, samples showed significant bactericidal activity against Micrococcus luteus with significantly less-observed bacteria in the measured plate, while the inhibition zone for Escherichia coli was 1 cm. The produced biodegradable electrospun membranes have multiple potential applications in many fields; especially for medical, antibacterial, and food packaging. This work reports the results for moisture and oxygen transfer of the membranes as a proposed application in food wrapping.

Optical fiber relative-humidity sensor with polyvinyl alcohol film

2004 ◽  
Vol 43 (21) ◽  
pp. 4127 ◽  
Author(s):  
Ainhoa Gastón ◽  
Fátima Pérez ◽  
Joaquín Sevilla
Keyword(s):  
Relative Humidity ◽  
Polyvinyl Alcohol ◽  
Optical Fiber ◽  
Humidity Sensor ◽  
Polyvinyl Alcohol Film ◽  
Relative Humidity Sensor

Preparation and Characterization of Calcium Metaphosphate Nanofibers via Electrospinning

2007 ◽  
Vol 330-332 ◽  
pp. 207-210 ◽  
Author(s):  
Timur R. Tadjiev ◽  
Sung Su Chun ◽  
Hong Mi Kim ◽  
Inn Kyu Kang ◽  
Suk Young Kim
Keyword(s):  
Calcium Nitrate ◽  
Electrospun Nanofibers ◽  
Heat Treatment Condition ◽  
Calcium Nitrate Tetrahydrate ◽  
Mixed Solution ◽  
Electrospinning Technique ◽  
Heat Treated ◽  
Nitrate Tetrahydrate ◽  
Phosphorus Precursor ◽  
Viscous Solutions

Bioresorbable calcium metaphosphate (CMP) nanofibers were produced by an electrospinning technique. In order to produce the nanofibers, CMP sol was prepared by the mixing of two precursors, such as calcium nitrate tetrahydrate (Ca[NO3]⋅4H2O) and triethyl phosphate (TEP, [C2H5O]3PO), using methyl alcohol as a solvent. The Ca/P ratio of the mixture was set to be 0.50 to produce stoichiometric CMP sol. At least 5 hrs of pre-hydrolysis of phosphorus precursor were required to obtain β-CMP phase. Viscous solutions for the electrospinning were made by the mixing of CMP sol and high-molecular weight polymeric solution at various ratios. The ratio of CMP sol and polymer solution was controlled to obtain an appropriate viscosity for the electrospinning. As-electrospun CMP nanofibers were dried in a drying oven at 70°C for 24 hrs and then heat-treated at various temperatures at a ramp of 1°C/min in air for 1hr. The as-electrospun and heat-treated CMP nanofibers were characterized using X-ray analysis, FT-IR, TG-DTA and SEM techniques. The results showed that the preparation of CMP sol, mixed solution properties, and heat-treatment condition of as-electrospun nanofibers significantly affect the spinability and surface morphology of the CMP nanofibers.

scholarly journals On the design and characterisation of a microwave microstrip resonator for gas sensing applications

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 54
Author(s):  
Giovanni Gugliandolo ◽  
Davide Aloisio ◽  
Giuseppe Campobello ◽  
Giovanni Crupi ◽  
Nicola Donato
Keyword(s):  
Relative Humidity ◽  
Reflection Coefficient ◽  
Humidity Sensor ◽  
Gas Sensing ◽  
Microstrip Resonator ◽  
Resonant Frequencies ◽  
Sensing Applications ◽  
Sensing Material ◽  
Central Disk ◽  
Humidity Monitoring

This study focuses on the microwave characterisation of a microstrip resonator aimed for gas sensing applications. The developed one-port microstrip resonator, consisting of three concentric rings with a central disk, is coupled to a 50-Ohm microstrip feedline through a small gap. A humidity sensing layer is deposited on this gap by drop-coating an aqueous solution of Ag@alpha-Fe<sub>2</sub>O<sub>3</sub> nanocomposite. The operation principle of the developed humidity sensor is based on the change of the dielectric properties of the Ag@alpha-Fe<sub>2</sub>O<sub>3</sub> nanocomposite when the relative humidity is varied. However, it should be underlined that, depending on the choice of the sensing material, different target gases of interest can be detected with the proposed structure. The frequency-dependent response of the sensor is obtained using the reflection coefficient measured from 3.5 GHz to 5.6 GHz with relative humidity ranging from 0 %rh to 83 %rh. The variation of the humidity concentration strongly impacts on the two resonances detected in the measured reflection coefficient. In particular, an increase of the humidity level leads to lowering both resonant frequencies, which can be used as sensing parameters for humidity monitoring purpose. An exponential function has been used to accurately model the two resonant frequencies as a function of the humidity.

scholarly journals Capacitive and Conductometric Type Dual-Mode Relative Humidity Sensor Based on 5,10,15,20-tetra Phenyl Porphyrinato Nickel (II) (TPPNi)

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3336
Author(s):  
Rizwan Akram ◽  
Muhammad Yaseen ◽  
Zahid Farooq ◽  
Ayesha Rauf ◽  
Ziyad M. Almohaimeed ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Humidity Sensor ◽  
Dynamic Range ◽  
Layer Structure ◽  
Synthesis Process ◽  
Microwave Assisted Synthesis ◽  
Electrode Gap ◽  
Sensing Material ◽  
Increasing Demand ◽  
Humidity Monitoring

(1) Background: A quest for a highly sensitive and reliable humidity monitoring system for a diverse variety of applications is quite vital. Specifically, the ever-increasing demand of humidity sensors in applications ranging from agriculture to healthcare equipment (to cater the current demand of COVID-19 ventilation systems), calls for a selection of suitable humidity sensing material. (2) Methods: In the present study, the TPPNi macromolecule has been synthesized by using a microwave-assisted synthesis process. The layer structure of the fabricated humidity sensor (Al/TPPNi/Al) consists of pair of planar 120 nm thin aluminum (Al) electrodes (deposited by thermal evaporation) and ~160 nm facile spin-coated solution-processable organic TPPNi as an active layer between the ~40 µm electrode gap. (3) Results: Electrical properties (capacitance and impedance) of sensors were found to be substantially sensitive not only on relative humidity but also on the frequency of the input bias signal. The proposed sensor exhibits multimode (capacitive and conductometric) operation with significantly higher sensitivity ~146.17 pF/%RH at 500 Hz and 48.23 kΩ/%RH at 1 kHz. (4) Conclusions: The developed Al/TPPNi/Al surface type humidity sensor’s much-improved detecting properties along with reasonable dynamic range and response time suggest that it could be effective for continuous humidity monitoring in multi environmental applications.

scholarly journals Development of La3+Doped CeO2Thick Film Humidity Sensors

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Chunjie Wang ◽  
Aihua Zhang ◽  
Hamid Reza Karimi
Keyword(s):  
Relative Humidity ◽  
High Performance ◽  
Humidity Sensor ◽  
Humidity Sensors ◽  
Response Recovery ◽  
Relative Humidity Range ◽  
Response And Recovery ◽  
Sensitive Characteristics ◽  
Humidity Range ◽  
Maximum Humidity

The humidity sensitive characteristics of the sensor fabricated from 10 mol% La2O3doped CeO2nanopowders with particle size 17.26 nm synthesized via hydrothermal method were investigated at different frequencies. It was found that the sensor shows high humidity sensitivity, rapid response-recovery characteristics, and narrow hysteresis loop at 100 Hz in the relative humidity range from 11% to 95%. The impedance of the sensor decreases by about five orders of magnitude as relative humidity increases. The maximum humidity hysteresis is about 6% RH, and the response and recovery time is 12 and 13 s, respectively. These results indicate that the nanosized La2O3doped CeO2powder has potential application as high-performance humidity sensor.

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