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.

Capacitive and Conductometric type Dual-Mode Relative Humidity Sensor based on 5,10,15,20-tetra phenyl porphyrinato nickel (II) (TPPNi)

2021 ◽  
Author(s):  
Rizwan Akram ◽  
Muhammad Yaseen ◽  
Zahid Farooq ◽  
Ayesha Rauf ◽  
Karwan Wasman Qadir ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Humidity Sensor ◽  
Dynamic Range ◽  
Layer Structure ◽  
Soret Band ◽  
Organic Polymer ◽  
Synthesis Process ◽  
Microwave Assisted Synthesis ◽  
Electrode Gap ◽  
Electron Microscopic

Abstract In the present study, TPPNi 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 Aluminium (Al) electrodes (deposited by thermal evaporation) and ~ 160 nm facile spin-coated solution-processable organic polymer TPPNi as an active layer between the ~ 40 µm electrode gap which was created through shadow mask process. Physical characterization showed that synthesized TPPNi thin films are very well suitable for their application as ambient sensors based on location and width for Soret band from optical characterization, amorphous structure from XRD, and most importantly the porous surface morphology from field emission scanning electron microscopic study. 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. Our findings demonstrate that the TPPNi has higher humidity sensitivity at lower frequencies. 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. 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 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 ELECTROPOLYMERISATION AND CHARACTERISATION OF DOPED-POLYPYRROLE AS HUMIDITY SENSOR

2010 ◽  
Vol 6 (2) ◽  
pp. 189-194
Author(s):  
Siswoyo Siswoyo ◽  
Trio F. Nugroho ◽  
Zulfikar Zulfikar ◽  
Agus Subekti
Keyword(s):  
Relative Humidity ◽  
Conducting Polymer ◽  
Humidity Sensor ◽  
Synthesis Process ◽  
Principal Characteristic ◽  
Volatile Chemicals ◽  
New Type ◽  
R Value ◽  
The Stability ◽  
Sensor Stability

A new type of sensing materials for humidity measurement has been developed based on conducting polymer polypyrrole synthesised from pyrrole by adding some dopant compounds, bromide and chloride, it is prepared by potentiodynamic-electropolymerisation technique. Variation of dopant types and concentration has been carried out in order to investigate the effect of this variation to the change of polymeric conductivity when interacting with water vapour. Polypyrrole-Cl (Ppy-Cl) and polypyrrole-Br (Ppy-Br) exhibit a good principal characteristic as sensor candidate namely responding proportionally to humidly variation ranging 30% - 90% relative humidity. Characterisation test for the sensor candidates has been carried out for evaluating their linearity respond toward humidity, their stability in certain period and their reproducibility in some tests. The results show that Ppy-Cl and Ppy-Br showing good linearity respond with R value in a range of 0.95 - 0.99. Their reproducibility and sensitivity were relatively good, however their respond stability were only last in few days. The stability probably is related to the stability of resulted polymeric structure that very affected by synthesis process and dopant used. It is necessary to extend the use of other dopant materials and changing the synthesis process in order to improve sensor stability. In other hand it is also necessary to characterise other performance characteristic of the sensor namely response time, and interference effect of some volatile chemicals and other gases.   Keywords: polypyrrole, potentiodynamic, electropolymerisation, humidity sensor and conducting polymer

Hydrogel Coated Long Period Grating Sensor for High Relative Humidity Measurement

2014 ◽  
Vol 981 ◽  
pp. 616-619 ◽  
Author(s):  
Xiu Juan Yu ◽  
Jin Tao Zhang ◽  
Xue Feng Chen ◽  
Sheng Chun Liu
Keyword(s):  
Relative Humidity ◽  
Humidity Sensor ◽  
High Sensitivity ◽  
Dip Coating ◽  
Linear Increase ◽  
High Relative Humidity ◽  
Long Period Grating ◽  
Long Period ◽  
Dip Coating Technique ◽  
Humidity Monitoring

A very sensitive hydrogel coated long period grating (LPG) humidity sensor is developed and experimentally investigated for high relative humidity monitoring. A thin-film of PINPAM hydrogel is deposited onto the cladding of LPG by using dip-coating technique. The transmission spectrum of the coated LPG is studied at different humidity levels. For humidity levels greater than 95%, the resonant dip depth suffers a sharp linear increase with a span of 10.26 dB and the resonant wavelength suffers a redshift of 8.6nm.The proposed hydrogel coated LPG humidity sensor shows a high sensitivity of 2.86dB/%RH at high relative humidity region.

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

The Humidity Sensitive Behavior of Poly(Ethyleneimine)/Multiwall Carbon Nanotube Composite Films

2012 ◽  
Vol 531-532 ◽  
pp. 588-591
Author(s):  
Tao Zhu ◽  
Guang Zhong Xie ◽  
Ya Dong Jiang ◽  
Jian Liao ◽  
Hui Ling Tai
Keyword(s):  
Carbon Nanotube ◽  
Relative Humidity ◽  
Composite Films ◽  
Multiwall Carbon Nanotube ◽  
Sensing Material ◽  
Nanotube Composites ◽  
Interdigitated Microelectrode ◽  
Carbon Nanotube Composite ◽  
Multiwall Carbon ◽  
Sensitive Behavior

In this paper, a novel humidity sensor based on polymer-carbon nanotube composites was prepared and characterized. Two different methods were adopted to fabricate the humidity-sensing film for these sensors. The surface of the films was observed by a scanning electron microscope (SEM). The sensing material made up of poly(ethyleneimine) and multiwall carbon nanotube was sprayed on the interdigitated microelectrode pairs(IDTs). The resistance between the two electrodes was measured at different relative humidity levels at 19°C. The data shows that the resistance increases with the rise of the relative humidity over the range of 5-90% RH and that, the resistance increases almost linearly in the range of 5-71% RH. The response of the sensors to NO2 and NH3 were also examined, and the results reveal that the sensor is not sensitive to both of them.

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