Effects of Tungsten Disulphide Coating on Tapered Microfiber for Relative Humidity Sensing Applications

Tungsten disulphide (WS2) is a two-dimensional transition-metal dichalcogenide material that can be used to improve the sensitivity of a variety of sensing applications. This study investigated the effect of WS2 coating on tapered region microfiber (MF) for relative humidity (RH) sensing applications. The flame brushing technique was used to taper the standard single-mode fiber (SMF) into three different waist diameter sizes of MF 2, 5, and 10 µm, respectively. The MFs were then coated with WS2 via a facile deposition method called the drop-casting technique. Since the MF had a strong evanescent field that allowed fast near-field interaction between the guided light and the environment, depositing WS2 onto the tapered region produced high humidity sensor sensitivity. The experiments were repeated three times to measure the average transmitted power, presenting repeatability and sensing stability. Each MF sample size was tested with varying humidity levels. Furthermore, the coated and non-coated MF performances were compared in the RH range of 45–90% RH at room temperature. It was found that the WS2 coating on 2 µm MF had a high sensitivity of 0.0861 dB/% RH with linearity over 99%. Thus, MF coated with WS2 encourages enhancement in the evanescent field effect in optical fiber humidity sensor applications.

Download Full-text

Relative Humidity Sensors Based on Microfiber Knot Resonators—A Review

Sensors ◽

10.3390/s19235196 ◽

2019 ◽

Vol 19 (23) ◽

pp. 5196 ◽

Cited By ~ 3

Author(s):

Young-Geun Han

Keyword(s):

Relative Humidity ◽

High Sensitivity ◽

Physical Parameters ◽

Humidity Sensors ◽

Coating Materials ◽

High Q ◽

Sensing Applications ◽

Compact Size ◽

The Many ◽

Humidity Sensitivity

Recent research and development progress of relative humidity sensors using microfiber knot resonators (MKRs) are reviewed by considering the physical parameters of the MKR and coating materials sensitive to improve the relative humidity sensitivity. The fabrication method of the MKR based on silica or polymer is briefly described. The many advantages of the MKR such as strong evanescent field, a high Q-factor, compact size, and high sensitivity can provide a great diversity of sensing applications. The relative humidity sensitivity of the MKR is enhanced by concerning the physical parameters of the MKR, including the waist or knot diameter, sensitive materials, and Vernier effect. Many techniques for depositing the sensitive materials on the MKR surface are discussed. The adsorption effects of water vapor molecules on variations in the resonant wavelength and the transmission output of the MKR are described regarding the materials sensitive to relative humidity. The sensing performance of the MKR-based relative humidity sensors is discussed, including sensitivity, resolution, and response time.

Download Full-text

Polymer Based Whispering Gallery Mode Humidity Sensor

Sensors ◽

10.3390/s18072383 ◽

2018 ◽

Vol 18 (7) ◽

pp. 2383 ◽

Cited By ~ 4

Author(s):

Ann Petermann ◽

Thomas Hildebrandt ◽

Uwe Morgner ◽

Bernhard Roth ◽

Merve Meinhardt-Wollweber

Keyword(s):

Relative Humidity ◽

Humidity Sensor ◽

Real Life ◽

High Sensitivity ◽

Whispering Gallery Mode ◽

Whispering Gallery ◽

Humidity Measurements ◽

Wgm Resonators

Whispering gallery mode (WGM) resonators are versatile high sensitivity sensors, but applications regularly suffer from elaborate and expensive manufacturing and read-out. We have realized a simple and inexpensive concept for an all-polymer WGM sensor. Here, we evaluate its performance for relative humidity measurements demonstrating a sensitivity of 47 pm/% RH. Our results show the sensor concepts’ promising potential for use in real-life applications and environments.

Download Full-text

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.

Download Full-text

A high-sensitivity polyimide capacitive relative humidity sensor for monitoring anodically bonded hermetic micropackages

Journal of Microelectromechanical Systems ◽

10.1109/84.925735 ◽

2001 ◽

Vol 10 (2) ◽

pp. 197-204 ◽

Cited By ~ 69

Author(s):

M. Dokmeci ◽

K. Najafi

Keyword(s):

Relative Humidity ◽

Humidity Sensor ◽

High Sensitivity ◽

Relative Humidity Sensor

Download Full-text

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.

Download Full-text

On the design and characterisation of a microwave microstrip resonator for gas sensing applications

ACTA IMEKO ◽

10.21014/acta_imeko.v10i2.1039 ◽

2021 ◽

Vol 10 (2) ◽

pp. 54

Author(s):

Giovanni Gugliandolo ◽

Davide Aloisio ◽

Giuseppe Campobello ◽

Giovanni Crupi ◽

Nicola Donato

Keyword(s):

Relative Humidity ◽

Reflection Coefficient ◽

Humidity Sensor ◽

Gas Sensing ◽

Microstrip Resonator ◽

Resonant Frequencies ◽

Sensing Applications ◽

Sensing Material ◽

Central Disk ◽

Humidity Monitoring

This study focuses on the microwave characterisation of a microstrip resonator aimed for gas sensing applications. The developed one-port microstrip resonator, consisting of three concentric rings with a central disk, is coupled to a 50-Ohm microstrip feedline through a small gap. A humidity sensing layer is deposited on this gap by drop-coating an aqueous solution of Ag@alpha-Fe2O3 nanocomposite. The operation principle of the developed humidity sensor is based on the change of the dielectric properties of the Ag@alpha-Fe2O3 nanocomposite when the relative humidity is varied. However, it should be underlined that, depending on the choice of the sensing material, different target gases of interest can be detected with the proposed structure. The frequency-dependent response of the sensor is obtained using the reflection coefficient measured from 3.5 GHz to 5.6 GHz with relative humidity ranging from 0 %rh to 83 %rh. The variation of the humidity concentration strongly impacts on the two resonances detected in the measured reflection coefficient. In particular, an increase of the humidity level leads to lowering both resonant frequencies, which can be used as sensing parameters for humidity monitoring purpose. An exponential function has been used to accurately model the two resonant frequencies as a function of the humidity.

Download Full-text

Piezotronics modulates high sensitivity relative humidity sensor based on single tellurium microwire

Semiconductor Science and Technology ◽

10.1088/1361-6641/ab1fd0 ◽

2019 ◽

Vol 34 (7) ◽

pp. 075011 ◽

Cited By ~ 2

Author(s):

Jinzong Kou ◽

Aifang Yu ◽

Yudong Liu ◽

Mengmeng Jia ◽

Junmeng Guo ◽

...

Keyword(s):

Relative Humidity ◽

Humidity Sensor ◽

High Sensitivity ◽

Relative Humidity Sensor

Download Full-text

A Compact Double-Folded Substrate Integrated Waveguide Re-Entrant Cavity for Highly Sensitive Humidity Sensing

Sensors ◽

10.3390/s19153308 ◽

2019 ◽

Vol 19 (15) ◽

pp. 3308 ◽

Cited By ~ 2

Author(s):

Zhihua Wei ◽

Jie Huang ◽

Jing Li ◽

Junshan Li ◽

Xuyang Liu ◽

...

Keyword(s):

Humidity Sensor ◽

High Sensitivity ◽

Substrate Integrated Waveguide ◽

Humidity Sensing ◽

Food Industries ◽

High Q ◽

Sensing Applications ◽

Compact Size ◽

Highly Sensitive ◽

Humidity Chamber

In this study, an ultra-compact humidity sensor based on a double-folded substrate integrated waveguide (SIW) re-entrant cavity was proposed and analyzed. By folding a circular re-entrant cavity twice along its two orthogonally symmetric planes, the designed structure achieved a remarkable size reduction (up to 85.9%) in comparison with a conventional TM010-mode circular SIW cavity. The operating principle of the humidity sensor is based on the resonant method, in other words, it utilizes the resonant properties of the sensor as signatures to detect the humidity condition of the ambient environment. To this end, a mathematical model quantitatively relating the resonant frequency of the sensor and the relative humidity (RH) level was established according to the cavity perturbation theory. The sensing performance of the sensor was experimentally validated in a RH range of 30%–80% by using a humidity chamber. The measured absolute sensitivity of the sensor was calculated to be 135.6 kHz/%RH, and the corresponding normalized sensitivity was 0.00627%/%RH. It was demonstrated that our proposed sensor not only has the merits of compact size and high sensitivity, but also benefits from a high Q-factor and ease of fabrication and integration. These advantages make it an excellent candidate for humidity sensing applications in various fields such as the agricultural, pharmaceutical, and food industries.

Download Full-text

Hydrogel Coated Long Period Grating Sensor for High Relative Humidity Measurement

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.981.616 ◽

2014 ◽

Vol 981 ◽

pp. 616-619 ◽

Cited By ~ 2

Author(s):

Xiu Juan Yu ◽

Jin Tao Zhang ◽

Xue Feng Chen ◽

Sheng Chun Liu

Keyword(s):

Relative Humidity ◽

Humidity Sensor ◽

High Sensitivity ◽

Dip Coating ◽

Linear Increase ◽

High Relative Humidity ◽

Long Period Grating ◽

Long Period ◽

Dip Coating Technique ◽

Humidity Monitoring

A very sensitive hydrogel coated long period grating (LPG) humidity sensor is developed and experimentally investigated for high relative humidity monitoring. A thin-film of PINPAM hydrogel is deposited onto the cladding of LPG by using dip-coating technique. The transmission spectrum of the coated LPG is studied at different humidity levels. For humidity levels greater than 95%, the resonant dip depth suffers a sharp linear increase with a span of 10.26 dB and the resonant wavelength suffers a redshift of 8.6nm.The proposed hydrogel coated LPG humidity sensor shows a high sensitivity of 2.86dB/%RH at high relative humidity region.

Download Full-text