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

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.

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Tin Disulfide-Coated Microfiber for Humidity Sensing with Fast Response and High Sensitivity

Crystals ◽

10.3390/cryst11060648 ◽

2021 ◽

Vol 11 (6) ◽

pp. 648

Author(s):

Aijie Liang ◽

Jingyuan Ming ◽

Wenguo Zhu ◽

Heyuan Guan ◽

Xinyang Han ◽

...

Keyword(s):

Humidity Sensor ◽

Small Diameter ◽

High Sensitivity ◽

Large Change ◽

Small Variation ◽

Response Speed ◽

Fast Response ◽

Tin Disulfide ◽

Recovery Times ◽

Response And Recovery

Breath monitoring is significant in assessing human body conditions, such as cardiac and pulmonary symptoms. Optical fiber-based sensors have attracted much attention since they are immune to electromagnetic radiation, thus are safe for patients. Here, a microfiber (MF) humidity sensor is fabricated by coating tin disulfide (SnS2) nanosheets onto the surface of MF. The small diameter (~8 μm) and the long length (~5 mm) of the MF promise strong interaction between guiding light and SnS2. Thus, a small variation in the relative humidity (RH) will lead to a large change in optical transmitted power. A high RH sensitivity of 0.57 dB/%RH is therefore achieved. The response and recovery times are estimated to be 0.08 and 0.28 s, respectively. The high sensitivity and fast response speed enable our SnS2-MF sensor to monitor human breath in real time.

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Capacitive Humidity Sensors With High Sensitivity and Subsecond Response Times

IEEE Sensors Journal ◽

10.1109/jsen.2007.897363 ◽

2007 ◽

Vol 7 (6) ◽

pp. 955-956 ◽

Cited By ~ 56

Author(s):

John J. Steele ◽

Glen A. Fitzpatrick ◽

Michael J. Brett

Keyword(s):

Response Times ◽

High Sensitivity ◽

Humidity Sensors

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Evaluation Humidity Sensing Properties of Graphene/HS-TiO2 Nanocomposites

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2021.19446 ◽

2021 ◽

Vol 21 (10) ◽

pp. 5143-5149

Author(s):

Zhen Zhu ◽

Wang-De Lin

Keyword(s):

Room Temperature ◽

Response Times ◽

Sol Gel ◽

Hollow Spheres ◽

High Sensitivity ◽

Humidity Sensing ◽

X Ray ◽

Transmission Electron ◽

Recovery Times ◽

Relative Humidity Range

This paper reports on a nanocomposite synthesized by sol–gel procedure comprising graphene sheets with hollow spheres of titanium dioxide (G/HS-TiO2) with varying weight percentages of graphene for the purpose of humidity sensors. The surface morphology of the nanocomposite was characterized using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The structural properties were examined using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). The response to 12–80% RH at room temperature exhibited sensitivity (S = 135). However, the relative humidity range of 12–90% at room temperature exhibited higher sensitivity (S = 557). Sensors fabricated using the proposed nanocomposite exhibited high sensitivity to humidity, high stability, rapid response times, and rapid recovery times with hysteresis error of less than 1.79%. These results demonstrate the outstanding potential of his material for the monitoring of atmospheric humidity. This study also sought to elucidate the mechanisms underlying humidity sensing performance.

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

Nanoscale ◽

10.1039/c4nr00277f ◽

2014 ◽

Vol 6 (12) ◽

pp. 6521-6525 ◽

Cited By ~ 7

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.

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Highly chemoresistive humidity sensing using poly(ionic liquid)s

Chemical Communications ◽

10.1039/c6cc04056j ◽

2016 ◽

Vol 52 (54) ◽

pp. 8417-8419 ◽

Cited By ~ 26

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.

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Porous Nanostructured Gadolinium Aluminate for High-Sensitivity Humidity Sensors

Materials ◽

10.3390/ma14227102 ◽

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.

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Humidity Sensor - A Review of Nanostructured Zinc Oxide (ZnO)-Based Humidity Sensor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1109.395 ◽

2015 ◽

Vol 1109 ◽

pp. 395-400 ◽

Cited By ~ 2

Author(s):

A.S. Ismail ◽

M.H. Mamat ◽

Mohamad Rusop

Keyword(s):

Zinc Oxide ◽

Band Gap ◽

Humidity Sensor ◽

Preparation Method ◽

Low Cost ◽

Sol Gel ◽

Extreme Environment ◽

Humidity Sensors ◽

Humidity Sensing ◽

Gel Preparation

We have reviewed humidity sensors based on the Zinc oxide (ZnO) humidity sensor. There are only a few papers reviewing on the ZnO humidity sensor. The characteristics, structures, advantages, and fabrication methods of ZnO have been studied to understand the suitability of the ZnO to be applied at different kind of condition such as for extreme environment, low level humidity detection, and very high humidity level circumstances. The electrical and physical properties of ZnO humidity sensors such as sensitivity, response time, stability, uniformity, and crystallinity have also been discussed in this review. ZnO nanostructures have been widely used for humidity sensors because of its’ good stability, high sensitivity for humidity-sensing, low cost, and has a wide band gap. Sol-gel preparation method is commonly used to for ZnO humidity sensor fabrication since it can produce a film with high uniformity, simple process and low cost. Keywords: Humidity Sensor, Metal Oxide, Semiconducting Type, Ceramic Type, Humidity-Sensing, Band Gap, Sol-Gel Preparation Method.

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Synthesized of Highly Sensitive Tin (IV)-Doped Zinc Oxide Humidity Sensor

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1109.559 ◽

2015 ◽

Vol 1109 ◽

pp. 559-563

Author(s):

Ahmad Syakirin Ismail ◽

Mohd Firdaus Malek ◽

Muhammad Amir Ridhwan Abdullah ◽

Mohamad Hafiz Mamat ◽

M. Rusop

Keyword(s):

Zinc Oxide ◽

Recovery Time ◽

Humidity Sensor ◽

Sol Gel ◽

High Sensitivity ◽

Average Diameter ◽

Undoped Sample ◽

Immersion Method ◽

Response Recovery ◽

Highly Sensitive

High sensitivity Tin (IV) (Sn) - doped zinc oxide (ZnO) humidity sensor was deposited using sol-gel immersion method. The Sn-doped sample was deposited on glass substrate and undoped sample was also prepared to seem the improvement made through doping process. The analyses showed that the sensor’s morphology has become more porous and having lower average diameter of nanorods, high conductivity and higher response, recovery time, and sensitivity. The sensitivity of the sensor increased from 2 to 4 by doping with Sn.

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A Flexible Humidity Sensor Based on Co3O4 Nanoneedles with High Sensitivity and Quick Response

Journal of Nanoelectronics and Optoelectronics ◽

10.1166/jno.2020.2788 ◽

2020 ◽

Vol 15 (7) ◽

pp. 870-874

Author(s):

Qi Qi ◽

Qi Wang ◽

Nanliu Liu ◽

Xiaoping Zheng ◽

Xiongjie Ding ◽

...

Keyword(s):

Humidity Sensor ◽

High Sensitivity ◽

Current Sensor ◽

Quick Response ◽

Bending Tests ◽

Humidity Sensing ◽

Recovery Times ◽

Response And Recovery ◽

Sensing Performance ◽

Semilogarithmic Scale

A flexible humidity sensor has been realized based on Co3O4 nanoneedles via a deposition technique. High humidity sensing and excellent flexible properties are observed in the tests. The impedance of the as-prepared sensor decreases by nearly three orders of magnitude with increasing relative humidity (RH) from 11% to 95% on a semilogarithmic scale. The response and recovery times are about 3 and 6 s respectively. The maximum hysteresis is less than 4% under 80% RH. No obvious changes for the sensing performance can be obtained after 100 bending/extending cycles and bending tests. These performances make the current sensor a good candidate for flexible humidity detection.

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High-Speed, High-Sensitivity Polyimide Humidity Sensors Based on MEMS Microhotplates

MRS Proceedings ◽

10.1557/proc-1075-j07-04 ◽

2008 ◽

Vol 1075 ◽

Author(s):

Jea Sung Kim ◽

Tea Jin Kim ◽

Moon Sik Kang ◽

Kum Pyo Yoo ◽

Nam Ki Min

Keyword(s):

Thin Films ◽

High Speed ◽

Humidity Sensor ◽

High Sensitivity ◽

Time Response ◽

Polyimide Films ◽

Humidity Sensors

ABSTRACTPolyimides thin films, which are the most commonly used group of sensing materials for capacitive humidity sensors, were cured locally using MEMS microhotplates. The polyimide locally cured at temperature over 350 °C for 1 hour was fully cured. There were no significant differences in the polyimide thin films between cured in convection ovens and locally cured on microhotplate. The locally cured polyimide humidity sensor showed a linearity of 0.9995, a sensitivity of 0.766pF/%RH, a hysteresis of 0.6%RH, and a time response of 3 s. These results show the possibility of locally-cured polyimide films as high speed, high-sensitivity humidity sensors.

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