Fabrication of a surface type humidity sensor based on methyl green thin film, with the analysis of capacitance and resistance through neutrosophic statistics (original) (raw)
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2022 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS)
This paper presents a low cost, easy to fabricate, thin-film sensor. We used three different methods to make the thin film using two different base (film) materials: carbon and graphite. We briefly summarize the method and outcome of multi-layer thin film fabrication using spray coating, spin-coating, and drop-casting. The quality of the thin films is compared, and electrical resistance is characterized. The fabricated thin film is used to measure humidity and is characterized against a commercial humidity sensor (DHT22). The experimental details and results of humidity measurement are discussed. We were able to achieve resistance range of 5k-1.5k ohms for 40-80 % RH, respectively. Plans to further optimize the sensitivity of the sensor, in future is discussed.
Capacitive Humidity Sensor Based on Polymer Composite Thin Film
2018
Nowadays humidity sensors are used in every industry, such as in food, pharmaceuticals [1], medicine, [2] and agriculture [3, 4]. These commercial humidity sensors are quite expensive, complicated in operation, and have low sensitivity and stability because of the materials used as a sensing element [5]. It is difficult to maintain their operational cost, power losses, sensitivity and stability [4]. Therefore, it is essential for a sensor to have high sensitivity and stability, low cost, small hysteresis, wide linear range, simple operation, short response, and short recovery time [5, 6]. Electrical conduction is affected significantly by dipoles of water molecules, which makes it important for researchers to investigate the magnitude of change in impedance and capacitance of the samples with respect to varying relative humidity. The investigation becomes more important for composite materials due to the contribution of properties by two or more ingredients. Changing the constitutin...
Humidity-dependent characteristics of methyl-red thin film-based Ag/methyl-red/Ag surface-type cell
Physica E-low-dimensional Systems & Nanostructures, 2008
Capacitive and resistive humidity sensor Response and recovery time Hysteresis a b s t r a c t This paper describes the experimental results for humidity-dependent resistive and capacitive response of methyl-red thin films in a Ag/methyl-red/Ag surface-type cell. A 300-nm-thick film of methyl-red was deposited from 10 wt% solution in benzene by a spin coater at an angular speed of 2000 revolutions per minute (RPM) on a glass substrate with preliminary deposited metal electrodes to form the Ag/methyl-red/Ag surface-type cell. The length and width of the gap between the electrodes were 50 mm and 15 mm, respectively. The resistance of the film reduced from 37 to 17 MO with an elevation of relative humidity level over the whole humidity range. It was also observed that under the effect of humidity, the capacitance of the methyl-red thin film increased by 12 times. The capacitive/resistive sensor has a quasi-linear function with relative humidity in the range of 30-95% and has a small hysteresis. The response and recovery time of the sensor was about 10 s for the capacitive sensor. The humidity-dependent resistive and capacitive properties of this sensor make it promising for use in a humidity meter.
2014
The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability.
The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability.
Journal of Semiconductors, 2015
The humidity sensing properties of the thin films of an organic semiconductor material orange dye (OD) and its composite with CNTs deposited at high gravity conditions have been reported. Impedance, phase angle, capacitance and dissipation of the samples were measured at 1 kHz and room temperature conditions. The impedance decreases and capacitance increases with an increase in the humidity level. It was found that the sensitivity of the OD-based thin film samples deposited at high gravity condition is higher than the samples deposited at low gravity condition. The impedances and capacitance sensitivities of the of the samples deposited under high gravity condition are 6.1 times and 1.6 times higher than the films deposited under low gravity condition.
Ag/PEPC/NiPc/ZnO/Ag thin film capacitive and resistive humidity sensors
Journal of Semiconductors, 2010
A thin film of blended poly-N-epoxypropylcarbazole (PEPC) (25 wt.%), nickel phthalocyanine (NiPc) (50 wt.%) and ZnO nano-powder (25 wt.%) in benzene (5 wt.%) was spin-coated on a glass substrate with silver electrodes to produce a surface-type Ag/PEPC/NiPc/ZnO/Ag capacitive and resistive sensor. Sensors with two different PEPC/NiPc/ZnO film thicknesses (330 and 400 nm) were fabricated and compared. The effects of humidity on capacitance and resistance of the Ag/PEPC/NiPc/ZnO/Ag sensors were investigated at two frequencies of the applied voltage: 120 Hz and 1 kHz. It was observed that at 120 Hz under humidity of up to 95% RH the capacitance of the sensors increased by 540 times and resistance decreased by 450 times with respect to humidity conditions of 50% RH. It was found that the sensor with a thinner semiconducting film (330 nm) was more sensitive than the sensor with a thicker film (400 nm). The sensitivity was improved when the sensor was used at a lower frequency as compared with a high frequency. It is assumed that the humidity response of the sensors is associated with absorption of water vapors and doping of water molecules in the semiconductor blend layer. This had been proven by simulation of the capacitance-humidity relationship.
Bi-layer capacitive type light and humidity sensors
2008
In this work, we have investigated the capacitive type light and humidity sensors fabricated by using cellulose and copper phtalocyanine (CuPc). Films of cellulose were deposited on glass substrates with preliminary deposited metallic electrodes followed by deposition of CuPc films. The capacitances of the samples were evaluated under the effect of light and humidity. It was observed that the capacitance of the sensor increases with increase in light intensity and relative humidity level. Comparison of the samples with different electrodes shows that the light sensitivity of the sample having Al electrodes is 2 times greater than the Ag one.
Microporous copper chromite thick film based novel and ultrasensitive capacitive humidity sensor
Journal of Alloys and Compounds, 2020
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