Effects of graphene layer and gold nanoparticles on sensitivity of humidity sensors

2020 ◽  
Vol 3 (1) ◽  
pp. 20-27
Author(s):  
Jiawei Bao ◽  
Niloofar Hashemi ◽  
Jingshuai Guo ◽  
Nicole N. Hashemi
Keyword(s):  
Gold Nanoparticles ◽  
Relative Humidity ◽  
Graphene Layer ◽  
Humidity Sensor ◽  
Response Times ◽  
Humidity Sensors ◽  
Micro Electro Mechanical Systems ◽  
Layer Graphene ◽  
Different Response ◽  
The Relationship

Humidity sensors can be used to monitor body sweat. Here, we studied a humidity sensor that comprised of a graphene layer between two electrodes. The operating principle is that the humidity sensor will respond when vapor reaches the graphene layer from the top. Based on the humidity diffusion, the sensor measures the relative humidity (RH) with different response times. Graphene is a material with high diffusivity and small thickness that can increase the sensitivity of a sensor. Based on the micro electro mechanical systems (MEMS) method, we modeled the humidity sensor using COMSOL Multiphysics® transport of diluted species software. Additionally, we used the concentration values from the simulations to determine the relationship between capacitance and relative humidity. The sensitivity was found to be 3.379 × 10−11 pF/%RH for the 4-layer graphene, 1.210 × 10−14 pF/%RH for the 8-layer graphene, and 3.597 × 10−11 pF/%RH for the 16-layer graphene sensor. The sensitivity of 4-layer graphene with gold sensor is 3.872 × 10−13 pF/%RH which is smaller than 4-layer graphene sensor, and graphene with gold nanoparticles shows better response time than 4-layer graphene sensor.

Highly chemoresistive humidity sensing using poly(ionic liquid)s

2016 ◽  
Vol 52 (54) ◽  
pp. 8417-8419 ◽  
Author(s):  
Lingling Wang ◽  
Xiaochuan Duan ◽  
Wuyuan Xie ◽  
Qiuhong Li ◽  
Taihong Wang
Keyword(s):  
Ionic Liquid ◽  
Relative Humidity ◽  
High Performance ◽  
Humidity Sensor ◽  
High Sensitivity ◽  
Fast Response ◽  
Humidity Sensors ◽  
Humidity Sensing ◽  
Good Repeatability ◽  
Poly Ionic Liquid

A novel resistance type humidity sensor was fabricated using poly(ionic liquid)s, which exhibited high sensitivity, fast response, small hysteresis and good repeatability at a relative humidity (RH) in the range of 11–98%, making poly(ionic liquid)s as promising sensing materials for high-performance humidity sensors.

scholarly journals Porous Nanostructured Gadolinium Aluminate for High-Sensitivity Humidity Sensors

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7102
Author(s):  
Corneliu Doroftei ◽  
Liviu Leontie
Keyword(s):  
Relative Humidity ◽  
Significant Influence ◽  
Humidity Sensor ◽  
Sol Gel ◽  
High Sensitivity ◽  
Combustion Method ◽  
Humidity Sensors ◽  
Oxide Compound ◽  
P Type ◽  
Highly Porous

This paper presents the synthesis of gadolinium aluminate (GdAlO3), an oxide compound with a perovskite structure, for applications as a capacitive and/or resistive humidity sensor. Gadolinium aluminate was synthesized by the sol-gel self-combustion method. This method allowed us to obtain a highly porous structure in which open pores prevail, a structure favorable to humidity sensors. Most of the materials studied as capacitive/resistive humidity sensors have significant sensitivities only with respect to one of these types of sensors. In the case of the studied gadolinium aluminate with p-type electric conductivity, the relative humidity of the air has a significant influence on both capacitive and resistive types of electric humidity sensors. The capacity increases about 10,000 times, and the resistance decreases about 8000 times as the relative humidity increases from 0 to 98%. The investigated gadolinium aluminate can be used successfully to obtain high-sensitivity capacitive and/or resistive humidity sensors.

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.

scholarly journals PANI/MWCNT based humidity sensor

2019 ◽  
Vol 15 (33) ◽  
pp. 111-121
Author(s):  
Hammad R. Humud
Keyword(s):  
Relative Humidity ◽  
Humidity Sensor ◽  
Energy Gap ◽  
Low Frequency ◽  
Plasma Jet ◽  
Humidity Sensors ◽  
Surface Type ◽  
Weight Concentration ◽  
Nanocomposite Thin Films ◽  
Initial Capacity

Polyaniline Multi wall Carbon nanotube (PANI/MWCNTs) nanocomposite thin films have been prepared by Plasma jet polymerization at low frequency on glass substrate with preliminary deposited aluminum electrodes to form Al/PANI-MWCNT/Al surface-type capacitive humidity sensors, the gap between the electrodes about 50 μm and the MWCNTs weight concentration varied between 0, 1, 2, 3, 4%. The diameter of the MWCNTs was in the range of 8-15 nm and the length 10-55 μm. The capacitance-humidity relationships of the sensors were investigated at humidity levels from 35 to 90% RH. The electrical properties showed that the capacity increased with increasing relative humidity, and that the sensitivity of the sensor increases with the increase of the additive (MWCNTs); while each of the response time and the recovery time increasing with concentration. The change in MWCNTs concentration leads to a change in the energy gap as well as the initial capacity. The capacitance increases linearly with the relative humidity at MWCNTs concentration of 3% for thus the possibility of manufacturing humidity sensor with good specifications at this concentration.

scholarly journals The Optoelectronic Sensor Relative Humidity

2020 ◽  
Vol 6 (10) ◽  
pp. 244-252
Author(s):  
M. Matbabayev
Keyword(s):  
Relative Humidity ◽  
Continuous Monitoring ◽  
Humidity Sensor ◽  
Block Diagram ◽  
Air Humidity ◽  
Humidity Sensors ◽  
Laboratory Installation ◽  
Object A ◽  
Optoelectronic Sensor ◽  
Controlled Object

This paper discusses the main characteristics of atmospheric air, the selected closed object on which the relative humidity depends to a certain extent, as well as a laboratory installation for studying the principle of constructing an optoelectronic sensor for measuring relative humidity. A description and diagram of the air humidity sensor, a block diagram of the installation for continuous monitoring of air humidity in the controlled object, a device for calibrating humidity sensors, and an algorithm for calibrating humidity sensors are given.

scholarly journals Gr/3D–ZnO Nanocomposites as Humidity Sensors with Enhanced Sensing Response

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1623
Author(s):  
Wang-De Lin ◽  
You-Chen Lin ◽  
Ren-Jang Wu ◽  
Murthy Chavali
Keyword(s):  
Raman Spectroscopy ◽  
Zinc Oxide ◽  
Humidity Sensor ◽  
Response Times ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Atmospheric Humidity ◽  
Humidity Sensors ◽  
Structure And Morphology ◽  
Recovery Times

This work introduces a novel humidity sensor based on a nanocomposite material comprising graphene decorated with three-dimensional flower-like structures of zinc oxide (Gr/3D–ZnO) fabricated via a hydrothermal method with various weight percentages of graphene. The surface structure and morphology of the Gr/3D–ZnO nanocomposite were analyzed using XRD, EDS, SEM, TEM, and Raman spectroscopy. The influence of humidity on the electrical properties of the nanocomposite was also investigated. Experiment results revealed that the nanocomposite with 70 wt% of graphene provided high sensitivity (S = 446) with rapid response times (120 s) and recovery times (160 s). These results demonstrate the excellent potential of the proposed Gr/3D–ZnO nanocomposite in monitoring atmospheric humidity. A discussion on the mechanism underlying the effects of humidity on the Gr/3D–ZnO nanocomposite is also provided.

Humidity Sensors Based on Nanostructured Materials

2006 ◽  
Vol 51 ◽  
pp. 197-200
Author(s):  
S. Krutovertsev ◽  
A. Tarasova ◽  
L. Krutovertseva ◽  
A. Zorin ◽  
O. Ivanova
Keyword(s):  
Relative Humidity ◽  
Nanostructured Materials ◽  
Humidity Sensor ◽  
Dew Point ◽  
Humidity Sensors ◽  
Humidity Range

Constraction and characteristics of sorption polymeric relative humidity sensors, sorption SiOx microhumidity sensors, and condensation type (dew point) sensors are compared. The characteristics of the sensors are examined in dew point range from -80 to +20oC. An integrated multifunctional humidity sensor, for measurements in wide humidity range at different conditions is developed. The sensors are intended for use in various branches of industry, and in scientific researches.

scholarly journals Humidity Sensor Based on Multi-Walled Carbon Nanotube Thin Films

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
C. L. Cao ◽  
C. G. Hu ◽  
L. Fang ◽  
S. X. Wang ◽  
Y. S. Tian ◽  
...  
Keyword(s):  
Thin Films ◽  
Carbon Nanotube ◽  
Relative Humidity ◽  
Humidity Sensor ◽  
Sensitive Material ◽  
Humidity Sensors ◽  
Multi Walled Carbon Nanotube ◽  
Chemically Treated ◽  
Humidity Sensitivity ◽  
Higher Sensitivity

The properties of the humidity sensors made of chemically treated and untreated multi-walled carbon nanotube (MWCNT) thin films are investigated systematically. It shows that both the chemically treated and untreated MWCNT thin films demonstrate humidity sensitive properties, but the former have stronger sensitivity than the latter. In the range of 11%–98% relative humidity (RH), the resistances of the chemically treated and untreated MWCNT humidity sensors increase 120% and 28%, respectively. Moreover, the treated humidity sensors showed higher sensitivity and better stability. In addition, the response and recover properties, and stabilization of the humidity sensors are measured, and the humidity sensitive mechanisms of the sensors are analyzed. The humidity sensitivity of carbon nanotube thin films indicates it promise as a kind of humidity sensitive material.

Performance and Modeling of a Nanostructured Relative Humidity Sensor

2007 ◽  
Vol 1054 ◽  
Author(s):  
Mike Taschuk ◽  
John Steele ◽  
Mike Brett
Keyword(s):  
Dielectric Constant ◽  
Relative Humidity ◽  
Humidity Sensor ◽  
Large Change ◽  
Glancing Angle Deposition ◽  
Dielectric Constants ◽  
Tio2 Thin Films ◽  
Humidity Sensors ◽  
Glancing Angle ◽  
Angle Deposition

ABSTRACTCapacitive humidity sensors were fabricated using interdigitated electrodes coated with amorphous nanostructured TiO2 thin films grown by glancing angle deposition. The sensor exhibited a large change in capacitance, increasing exponentially from ∼ 1 nF to ∼ 1 μF for an increase in relative humidity from 2 % to 92 %. A simple model of the capacitive response and dielectric constant of the devices has been developed and compared to the experimental results. From this comparison, it is clear that the magnitude of the device response observed cannot be explained with bulk dielectric constants or literature values.

scholarly journals Novel humidity sensors based on nanomodified Portland cement

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thanyarat Buasiri ◽  
Karin Habermehl-Cwirzen ◽  
Lukasz Krzeminski ◽  
Andrzej Cwirzen
Keyword(s):  
Electrical Resistivity ◽  
Relative Humidity ◽  
Portland Cement ◽  
Threshold Value ◽  
High Humidity ◽  
Humidity Sensors ◽  
The Relationship ◽  
Humidity Range ◽  
Very High

AbstractCommonly used humidity sensors are based on metal oxides, polymers or carbon. Their sensing accuracy often deteriorates with time, especially when exposed to higher temperatures or very high humidity. An alternative solution based on the utilization of Portland cement-based mortars containing in-situ grown carbon nanofibers (CNFs) was evaluated in this study. The relationship between the electrical resistivity, CNF content and humidity were determined. The highest sensitivity was observed for samples containing 10 wt.% of the nanomodified cement which corresponded to 0.27 wt.% of CNFs. The highest calculated sensitivity was approximately 0.01024 per 1% change in relative humidity (RH). The measured electrical resistivity is a linear function of the RH in the humidity range between 11 and 97%. The percolation threshold value was estimated to be at around 7 wt.% of the nanomodified cement, corresponding to ~ 0.19 wt.% of CNFs.

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