scholarly journals Low-Hysteresis and Fast Response Time Humidity Sensors Using Suspended Functionalized Carbon Nanotubes

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 680 ◽  
Author(s):  
Shivaram Arunachalam ◽  
Ricardo Izquierdo ◽  
Frederic Nabki
Keyword(s):  
Carbon Nanotubes ◽  
Response Time ◽  
Humidity Sensor ◽  
Fast Response ◽  
Hysteresis Curve ◽  
Humidity Sensors ◽  
Fold Reduction ◽  
Stable Performance ◽  
Suspended Structure ◽  
Temperature Surface

A humidity sensor using suspended carbon nanotubes (CNTs) was fabricated using a low-temperature surface micromachining process. The CNTs were functionalized with carboxylic acid groups that facilitated the interaction of water vapor with the CNTs. The humidity sensor showed a response time of 12 s and a recovery time of 47 s, along with superior hysteresis and stable performance. The hysteresis curve area of the suspended structure is 3.6, a 3.2-fold reduction in comparison to the non-suspended structure. A comparative study between suspended and non-suspended devices highlights the advantages of using a suspended architecture.

scholarly journals Nonporous Inorganic Nanoparticle-Based Humidity Sensor: Evaluation of Humidity Hysteresis and Response Time

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3858
Author(s):  
Shinya Kano ◽  
Harutaka Mekaru
Keyword(s):  
Response Time ◽  
Humidity Sensor ◽  
Silica Nanoparticle ◽  
Fast Response ◽  
Inorganic Nanoparticles ◽  
Humidity Sensors ◽  
Inorganic Nanoparticle ◽  
Response Recovery ◽  
Recovery Times ◽  
Nanoparticle Film

Fast-response humidity sensors using nanomaterials are attractive and have been intensively studied. Among the various nanomaterials, nonporous inorganic nanoparticles are suitable for use in humidity sensitive films for sensors. Here, we focus on a nonporous inorganic nanoparticle film and investigate a humidity sensor using the film. Hysteresis error and a dynamic response to a change of humidity are fundamental specifications of humidity sensors. A humidity sensor using a 50 nm silica nanoparticle film shows a hysteresis error of 2% at 85% RH and a response/recovery time of 2.8/2.3 s in 30% RH to 70% RH. We also summarize response/recovery times and hysteresis errors of state-of-the-art humidity sensors. As compared to those of commercial sensors and porous nanoparticle-based sensors evaluated using saturated salt solutions, the fabricated sensor shows a comparative hysteresis error and shorter response time.

High-performance humidity sensors from Ni(SO4)0.3(OH)1.4 nanobelts

Nanoscale ◽  
2014 ◽  
Vol 6 (12) ◽  
pp. 6521-6525 ◽  
Author(s):  
Ming Zhuo ◽  
Yuejiao Chen ◽  
Tao Fu ◽  
Haonan Zhang ◽  
Zhi Xu ◽  
...  
Keyword(s):  
High Performance ◽  
Humidity Sensor ◽  
High Sensitivity ◽  
Fast Response ◽  
Humidity Sensors ◽  
Term Stability ◽  
Long Term Stability

Ni(SO4)0.3(OH)1.4 nanobelts are utilized in a humidity sensor by a facile method. The nanobelt based sensor shows a high sensitivity, fast response and long-term stability in the sensing process.

scholarly journals Evaluation of radiosonde humidity sensors at low temperature using ultralow-temperature humidity chamber

2018 ◽  
Vol 15 ◽  
pp. 207-212 ◽  
Author(s):  
Byung Il Choi ◽  
Sang-Wook Lee ◽  
Sang-Bong Woo ◽  
Jong Chul Kim ◽  
Yong-Gyoo Kim ◽  
...  
Keyword(s):  
Water Vapor ◽  
Low Temperature ◽  
Response Time ◽  
Humidity Sensor ◽  
Weather Prediction ◽  
Observation Data ◽  
Humidity Sensors ◽  
Ultralow Temperature ◽  
Humidity Chamber ◽  
Sensing Characteristics

Abstract. Accurate measurements of temperature and water vapor in the upper-air are of great interest in relation to weather prediction and climate change. Those measurements are mostly conducted using radiosondes equipped with a variety of sensors that are flown by a balloon up to lower stratosphere. Reference Upper Air Network (GRUAN) has identified water vapor pressure as one of the most important measurands and has set an accuracy requirement of 2 % in terms of the mixing ratio. In order to achieve the requirement, many errors in the humidity measurement such as a temperature dependency in sensing characteristics including measurement values and response time need to be corrected because humidity sensors of radiosondes pass through low-pressure (1 kPa) and low-temperature (−80 ∘C) environments in the upper-air. In this paper, the humidity sensing characteristics of Jinyang radiosonde sensors in relation to temperature dependencies were evaluated at low temperature using a newly developed ultralow-temperature humidity chamber. The sensitivity characteristic curve of the radiosonde sensors was evaluated down to −80 ∘C, and the calibration curves of the humidity sensor and the temperature sensor were obtained. The response time of humidity sensor slowly increased from 52 to 116 s at the temperature from 20 to −40 ∘C, respectively, and then rapidly increased to almost one hour at −80 ∘C. Those results will help to improve the reliability of the upper-air observation data.

Fast-response ionogel humidity sensor for real-time monitoring of breathing rate

2019 ◽  
Vol 3 (3) ◽  
pp. 484-491 ◽  
Author(s):  
Songhua Xiao ◽  
Jianxia Nie ◽  
Rou Tan ◽  
Xiaochuan Duan ◽  
Jianmin Ma ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Real Time ◽  
Humidity Sensor ◽  
Fast Response ◽  
Breathing Rate ◽  
Real Time Monitoring ◽  
Silica Network ◽  
Humidity Sensors ◽  
Human Breath

Ionogel-based chemoresistive humidity sensors have been successfully fabricated through ionothermal assembly of ionic liquids into a silica network, which exhibited superior humidity performances. Fast substantial impedance changes were observed with changing humidity for real-time monitoring of human breath.

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 Design and Verification of Humidity Sensors Based on Magnesium Oxide Micro-Arc Oxidation Film Layers

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1736 ◽  
Author(s):  
Mingqiang Pan ◽  
Jun Sheng ◽  
Jizhu Liu ◽  
Zeming Shi ◽  
Lei Jiu
Keyword(s):  
Magnesium Oxide ◽  
Humidity Sensor ◽  
Fast Response ◽  
High Humidity ◽  
Response Signal ◽  
Humidity Sensors ◽  
Average Output ◽  
Important Indicator ◽  
Detection Range ◽  
Micro Arc Oxidation

Humidity detection range is an important indicator for measuring the performance of humidity sensors, but semiconductor humidity sensors often face the problems of narrow detection ranges and insufficient detection sensitivities. In this paper, a magnesium oxide (MgO) humidity sensor based on micro-arc oxidation (MAO) technology was designed to solve these problems by simultaneously using impedance and capacitance as the response signals, as well as by normalizing the output of the two signals. The experimental results showed that the average output of the micro-arc MgO ceramic film, with impedance as the response signal, could reach 150 in the low relative humidity(RH) range (11.3–67% RH), which was much higher than its sensitivity in the high humidity range (< 1), and the film showed fast response (13 s) and recovery (61 s). Under high humidity conditions (67–97.3% RH), with capacitance as the response signal, the output of the micro-arc MgO was as high as 120. Therefore, the micro-arc MgO humidity sensor with impedance, and the sensor with capacitance as the response signal, demonstrated good stability in low humidity and in high humidity environments, respectively, indicating that the method of selecting appropriate response signals for different humidity environments can be applied to extend the humidity detection range of sensing material, and to improve the humidity detection capability of a sensor.

scholarly journals Preparation and Performance Analysis of Ag/ZnO Humidity Sensor

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 857
Author(s):  
Peng Li ◽  
Shuguo Yu ◽  
Hongyan Zhang
Keyword(s):  
Active Sites ◽  
Humidity Sensor ◽  
Molar Ratio ◽  
Water Molecules ◽  
Humidity Sensors ◽  
Response Recovery ◽  
Highly Sensitive ◽  
Stable Performance ◽  
And Performance ◽  
Decomposition Of Water

Highly sensitive silver (Ag) modified zinc oxide (ZnO) humidity sensors were prepared by hydrothermal synthesis and the mechanism was studied. Experimental results show that Ag-modified ZnO can effectively enhance the performance of a humidity sensor. Large number of oxygen vacancies and many active sites are generated on the surface when molar ratio of Ag+ to Zn2+ is 1:100, which can accelerate the decomposition of water molecules on surface of the material, thereby improving the response of humidity sensor. Moreover, the linearity of ZnO humidity sensor is greatly improved by silver nanoparticles. Compared with previously reported ZnO-based humidity sensors, Ag/ZnO humidity sensors have a better response (151,700%), good linearity, low hysteresis (3%), and short response/recovery time (36/6 s). At the same time, it is found that the light had little effect on the performance of Ag/ZnO. Therefore, this kind of ZnO sensor with stable performance and excellent performance is expected to be used in the detection of relative humidity in conventional environments.

scholarly journals Humidity Sensors with Shielding Electrode Under Interdigitated Electrode

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 659 ◽  
Author(s):  
Hong Liu ◽  
Qi Wang ◽  
Wenjie Sheng ◽  
Xubo Wang ◽  
Kaidi Zhang ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
High Sensitivity ◽  
Fast Response ◽  
Capacitive Sensors ◽  
Humidity Sensors ◽  
Interdigitated Electrode ◽  
Response Recovery ◽  
Chip Fabrication ◽  
Good Agreement ◽  
Capacitive Humidity Sensor

Recently, humidity sensors have been investigated extensively due to their broad applications in chip fabrication, health care, agriculture, amongst others. We propose a capacitive humidity sensor with a shielding electrode under the interdigitated electrode (SIDE) based on polyimide (PI). Thanks to the shielding electrode, this humidity sensor combines the high sensitivity of parallel plate capacitive sensors and the fast response of interdigitated electrode capacitive sensors. We use COMSOL Multiphysics to design and optimize the SIDE structure. The experimental data show very good agreement with the simulation. The sensitivity of the SIDE sensor is 0.0063% ± 0.0002% RH. Its response/recovery time is 20 s/22 s. The maximum capacitance drift under different relative humidity is 1.28% RH.

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