Humidity-dependent characteristics of methyl-red thin film-based Ag/methyl-red/Ag surface-type cell

Ahmad, Zubair; Sayyad, Muhammad Hassan; Saleem, M.; Karimov, Khasan S.; Shah, Masaud

doi:10.1016/j.physe.2008.05.018

Cited by 74 publications

(29 citation statements)

References 20 publications

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“…Electronics 2016, 5, 23 6 of 8 critical frequency may be attributed to the resistance of the device. Dielectric permittivity and mobility of charge carriers are believed to be responsible for the interdependence of the impedance of the sensor and frequency of the AC signal.…”

Section: Resultsmentioning

confidence: 99%

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Frequency Dependence of Electrical Parameters of an Organic-Inorganic Hybrid Composite Based Humidity Sensor

Akram

2016

Electronics

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Abstract:The present study highlights the interdependence of ambient humidity levels on the electrical parameters of organic-inorganic hybrid composite based humidity sensor at varied AC frequencies of input signal. Starting from the bottom, the layer stack of the fabricated humidity sensor was 200-nm silver (Ag) thin film and 4 µm spun-coated PEPC+NiPC+Cu 2 O active layer. Silver thin films were deposited by thermal evaporator on well cleaned microscopic glass slides, which served as a substrate. Conventional optical lithography procedure was adapted to define pairs of silver-silver surface electrodes with two sorts of configurations, i.e., interdigitated and rectangular. Humidity-sensitive layers of organic-inorganic composite were then spun-cast upon the channel between the silver electrodes. The changes in relative humidity levels induced variation in capacitance and impedance of the sensors. These variations in electrical parameters of sensors were also found to be highly dependent upon frequency of input AC signal. Our findings reveal that the organic-inorganic composite shows higher humidity sensitivity at smaller orders of frequency. This finding is in accordance with the established fact that organic semiconductors-based devices are not applicable for high frequency applications due to their lower charge carrier mobility values. Two distinct geometries of semiconducting medium between the silver electrodes were investigated to optimize the sensing parameters of the humidity sensor. Furthermore, the effect of temperature change on the resistance of organic composite has also been studied.

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Section: Resultsmentioning

confidence: 99%

“…Electronics 2016, 5, 23 3 of 8 film of silver on the glass substrates. A film thickness of 200 nm was obtained by passing 22A current through the tungsten filament for ~2 m. Meanwhile the pressure inside the thermal evaporator was kept below 10 −5 mbar.…”

Section: Methodsmentioning

confidence: 99%

Frequency Dependence of Electrical Parameters of an Organic-Inorganic Hybrid Composite Based Humidity Sensor

Akram

2016

Electronics

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“…It is well known that capacitance of the sensor is directly proportional to dielectric permittivity of organic thin film. Thus, when the relative-humidity increases, dielectric permittivity increases and consequently capacitance increases [33]. For calculating capacitance versus relative-humidity, the following expression can be used:…”

Section: Device Characterizationmentioning

confidence: 99%

“…However, in the succeeding physisorption layers, molecules are singly bonded and can be polarized easily, which in turn give rise to increased permittivity and capacitance of the sensor with increasing humidity levels. Later on, a point arrives when no more molecules are adsorbed because all the pores present in surface of the film get filled completely, making capacitance variation less conspicuous and device less sensitive to higher humidity levels [33].The explanation given here can be correlated with our results in the following manner; initially when chemisorption and initial physisorption layers are formed, capacitance remains unchanged below a certain humidity level (i.e. below 50 and 30% RH for 1 k Hz and 120 Hz, respectively).…”

Section: Device Characterizationmentioning

confidence: 99%

Investigating sensing properties of poly-(dioctylfluorene) based planar sensor

Rehman

Tahir

Hameed

et al. 2015

Materials Science in Semiconductor Processing

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“…Currently, meteorological detection humidity sensors can be divided into two categories, the first one is the resistive humidity sensor, and the other is the capacitive humidity sensor [10,11]. The most sensitive material used in resistive humidity sensors is LiCl [12], and this type of humidity sensor has the advantages of good sensing performance and good reliability, but its time response is slow and it presents undesired limitations in low or high humidity environments [13]. The capacitive humidity sensor is being widely used thank to its high sensitivity, low power consumption, fast response time and low fabrication cost [14].…”

Section: Introductionmentioning

confidence: 99%

A Radiosonde Using a Humidity Sensor Array with a Platinum Resistance Heater and Multi-Sensor Data Fusion

Shi

Luo

Zhao

et al. 2013

Sensors

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This paper describes the design and implementation of a radiosonde which can measure the meteorological temperature, humidity, pressure, and other atmospheric data. The system is composed of a CPU, microwave module, temperature sensor, pressure sensor and humidity sensor array. In order to effectively solve the humidity sensor condensation problem due to the low temperatures in the high altitude environment, a capacitive humidity sensor including four humidity sensors to collect meteorological humidity and a platinum resistance heater was developed using micro-electro-mechanical-system (MEMS) technology. A platinum resistance wire with 99.999% purity and 0.023 mm in diameter was used to obtain the meteorological temperature. A multi-sensor data fusion technique was applied to process the atmospheric data. Static and dynamic experimental results show that the designed humidity sensor with platinum resistance heater can effectively tackle the sensor condensation problem, shorten response times and enhance sensitivity. The humidity sensor array can improve measurement accuracy and obtain a reliable initial meteorological humidity data, while the multi-sensor data fusion technique eliminates the uncertainty in the measurement. The radiosonde can accurately reflect the meteorological changes.

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Humidity-dependent characteristics of methyl-red thin film-based Ag/methyl-red/Ag surface-type cell

Cited by 74 publications

References 20 publications

Frequency Dependence of Electrical Parameters of an Organic-Inorganic Hybrid Composite Based Humidity Sensor

Frequency Dependence of Electrical Parameters of an Organic-Inorganic Hybrid Composite Based Humidity Sensor

Investigating sensing properties of poly-(dioctylfluorene) based planar sensor

A Radiosonde Using a Humidity Sensor Array with a Platinum Resistance Heater and Multi-Sensor Data Fusion

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