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

Sensors ◽  
2019 ◽  
Vol 19 (15) ◽  
pp. 3308 ◽  
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.

A miniaturized evanescent mode HMSIW humidity sensor

2017 ◽  
Vol 10 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Chang-Ming Chen ◽  
Jun Xu
Keyword(s):  
Humidity Sensor ◽  
Split Ring Resonator ◽  
Evanescent Mode ◽  
Split Ring ◽  
Promising Candidate ◽  
Humidity Sensing ◽  
Complementary Split Ring Resonator ◽  
Sensing Applications ◽  
Sensing Material ◽  
Compact Size

A passive evanescent mode half-mode substrate integrated waveguide (HMSIW) resonator loaded with a complementary split ring resonator (CSRR) is designed and fabricated for humidity sensing applications. The use of the CSRR which is etched on the top plane of the HMSIW can significantly reduce the size of the device. Without any sensing material, the sensor which has a compact size of 0.17λg × 0.17λg can provide high humidity sensitivity up to 5.82 MHz/%relative humidity (RH) at high RH region (>84.3%). The results indicate that the proposed structure is a promising candidate for radio and microwave humidity sensing applications.

scholarly journals Relative Humidity Sensors Based on Microfiber Knot Resonators—A Review

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5196 ◽  
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.

scholarly journals Wide range and highly linear signal processed systematic humidity sensor array using Methylene Blue and Graphene composite

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Umair Khan ◽  
Gul Hassan ◽  
Rayyan Ali Shaukat ◽  
Qazi Muhammad Saqib ◽  
Mahesh Y. Chougale ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Linear Combination ◽  
Linear Function ◽  
Humidity Sensor ◽  
Sensor Array ◽  
Combination Method ◽  
Humidity Sensing ◽  
Sensing Applications ◽  
Wide Range ◽  
Graphene Flakes

AbstractThis paper proposes a signal processed systematic 3 × 3 humidity sensor array with all range and highly linear humidity response based on different particles size composite inks and different interspaces of interdigital electrodes (IDEs). The fabricated sensors are patterned through a commercial inkjet printer and the composite of Methylene Blue and Graphene with three different particle sizes of bulk Graphene Flakes (BGF), Graphene Flakes (GF), and Graphene Quantum Dots (GQD), which are employed as an active layer using spin coating technique on three types of IDEs with different interspaces of 300, 200, and 100 µm. All range linear function (0–100% RH) is achieved by applying the linear combination method of nine sensors in the signal processing field, where weights for linear combination are required, which are estimated by the least square solution. The humidity sensing array shows a fast response time (Tres) of 0.2 s and recovery time (Trec) of 0.4 s. From the results, the proposed humidity sensor array opens a new gateway for a wide range of humidity sensing applications with a linear function.

scholarly journals Hybrid Grating in Reduced-Diameter Fiber for Temperature-Calibrated High-Sensitivity Refractive Index Sensing

2019 ◽  
Vol 9 (9) ◽  
pp. 1923
Author(s):  
Biqiang Jiang ◽  
Zhen Hao ◽  
Dingyi Feng ◽  
Kaiming Zhou ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Refractive Index ◽  
Simultaneous Measurement ◽  
Surrounding Medium ◽  
High Sensitivity ◽  
Fiber Grating ◽  
Bragg Resonance ◽  
Core Mode ◽  
Promising Alternative ◽  
Sensing Applications ◽  
Highly Sensitive

We propose and experimentally demonstrate a hybrid grating, in which an excessively tilted fiber grating (Ex-TFG) and a fiber Bragg grating (FBG) were co-inscribed in a reduced-diameter fiber (RDF). The hybrid grating showed strong resonances due to coupling among core mode and a set of polarization-dependent cladding modes. This coupling showed enhanced evanescent fields by the reduced cladding size, thus allowing stronger interaction with the surrounding medium. Moreover, the FBG’s Bragg resonance confined by the thick cladding was exempt from the change of the surrounding medium’s refractive index (RI), and then the FBG can work as a temperature compensator. As a result, the Ex-TFG in RDF promised a highly sensitive RI measurement, with a sensitivity up to ~1224 nm/RIU near the RI of 1.38. Through simultaneous measurement of temperature and RI, the temperature dependence of water’s RI is then determined. Therefore, the proposed hybrid grating with a spectrum of multi-peaks embedded with a sharp Bragg resonance is a promising alternative for the simultaneous measurement of multi-parameters for many RI-based sensing applications.

A highly sensitive humidity sensor based on an aggregation-induced emission luminogen-appended hygroscopic polymer microresonator

2021 ◽  
Author(s):  
Airong Qiagedeer ◽  
Hiroshi Yamagishi ◽  
Minami Sakamoto ◽  
Hanako Hasebe ◽  
Fumitaka Ishiwari ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
High Sensitivity ◽  
Aggregation Induced Emission ◽  
Highly Sensitive ◽  
Self Assembled

A self-assembled microsphere resonator, comprising a hygroscopic polymer with aggregation-induced emission luminogen pendants, can sense humidity with high sensitivity and repeatability.

scholarly journals Highly Sensitive Temperature and Humidity Sensor Based on Carbon Nanotube-Assisted Mismatched Single-Mode Fiber Structure

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 521 ◽  
Author(s):  
Yuan ◽  
Qian ◽  
Liu ◽  
Wang ◽  
Yu
Keyword(s):  
Carbon Nanotube ◽  
Humidity Sensor ◽  
Single Mode ◽  
Small Region ◽  
Single Mode Fiber ◽  
Fiber Structure ◽  
Humidity Sensing ◽  
Highly Sensitive ◽  
Temperature And Humidity ◽  
Stable Performance

Here we report on a miniaturized optical interferometer in one fiber based on two mismatched nodes. The all-fiber structure shows stable performance of temperature and humidity sensing. For temperature sensing in large ranges, from 40 to 100 °C, the sensor has a sensitivity of 0.24 dB/°C, and the adjusted R-squared value of fitting result reaches 0.99461 which shows a reliable sensing result. With carbon nanotubes coating the surface of the fiber, the temperature sensitivity is enhanced from 0.24561 to 1.65282 dB/°C in a small region, and the performance of humidity sensing becomes more linear and applicable. The adjusted R-squared value of the linear fitting line for humidity sensing shows a dramatic increase from 0.71731 to 0.92278 after carbon nanotube coating, and the humidity sensitivity presents 0.02571 nm/%RH.

An intrinsically stretchable humidity sensor based on anti-drying, self-healing and transparent organohydrogels

2019 ◽  
Vol 6 (3) ◽  
pp. 595-603 ◽  
Author(s):  
Jin Wu ◽  
Zixuan Wu ◽  
Huihua Xu ◽  
Qian Wu ◽  
Chuan Liu ◽  
...  
Keyword(s):  
Humidity Sensor ◽  
Self Healing ◽  
Solvent Exchange ◽  
Humidity Sensing ◽  
Sensing Applications

A facile solvent-exchange strategy is devised to fabricate anti-drying, self-healing and transparent organohydrogels for stretchable humidity sensing applications.

Design of Conductive MWNTs/SiO2 Humidity Sensor Interface ASIC Based on AC Signals

2013 ◽  
Vol 562-565 ◽  
pp. 344-349
Author(s):  
Tuo Li ◽  
Xiao Wei Liu ◽  
Liang Yin ◽  
Chang Chun Dong
Keyword(s):  
Humidity Sensor ◽  
Work Group ◽  
High Sensitivity ◽  
Cmos Process ◽  
Humidity Sensing ◽  
Interface Circuit ◽  
Testing Frequency ◽  
Zero Offset ◽  
Different Response ◽  
Circuit Output

Previous research on MWNTs/SiO2 humidity sensing film by our work group has proved that MWNTs sensor has a different response mechanism to humidity at AC testing signals and shows greater testing stability and higher sensitivity, compared with traditional DC signal measurement. An interface circuit for conductive MWNTs/SiO2 humidity sensor is designed in this paper for humidity detection and prospection in miniaturization and integration. It aims at detecting the sensor’s humidity sensitive conductance signal at AC testing signals, and inhibiting the interference of capacitance signals. The ASIC demodulates the two signals by their phase difference and outputs a direct voltage proportional to conductance. The layout for ASIC is drawn by standard 0.5um P2M2 CMOS process and has a total area of 4*2mm2. In circuit level simulation by HSPICE which introduces practical data of the sensor’s humidity sensing characteristics, the relation of circuit output to conductance turns out to have great linearity at no more than 300 kHz and zero offset can be neglected at less than 100 kHz frequency. It is feasible to select proper testing frequency for high sensitivity and stability and make further investigations on the sensor’s frequency property.

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 The Effect of rGO-Doping on the Performance of SnO2/rGO Flexible Humidity Sensor

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3368
Author(s):  
Huangping Yan ◽  
Zilu Chen ◽  
Linyuan Zeng ◽  
Zijun Wang ◽  
Gaofeng Zheng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Performance ◽  
Humidity Sensor ◽  
High Sensitivity ◽  
Polyimide Film ◽  
Fast Response ◽  
Humidity Sensing ◽  
Transmission Electron ◽  
Bending Radius ◽  
New Applications

The development of a flexible and high-performance humidity sensor is essential to expand its new applications, such as personal health monitoring and early diagnosis. In this work, SnO2/rGO nanocomposites were prepared by one-step hydrothermal method. The effect of rGO-doping on humidity sensing performance was investigated. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy were used to characterize the nanostructure, morphology and chemical composition of SnO2/rGO nanocomposites. The SnO2/rGO humidity sensitive film was prepared by electrospinning on a polyimide film modified with gold electrodes. The humidity test results show that different doping ratios of rGO have different effects on humidity sensing properties. Among them, the sensor with 2 wt% rGO-doping has a high sensitivity (37,491.2%) within the humidity range as well as the fast response time (80 s) and recover time (4 s). Furthermore, the sensor with 2 wt% rGO-doping remains good flexibility and stability in the case of bending (1000 times). The sensitivity of the 2 wt% rGO-doping sensor at the bending radius (8 mm and 4 mm) is 48,219% and 91,898%, respectively. More importantly, the sensor could reflect different breathing states clearly and track breathing intervals as short as 3 s. The SnO2/rGO flexible humidity sensor with accuracy, flexibility and instantaneity as well as the facile fabrication strategy is conceivable to be applied in the potential application for human health real-time monitoring.

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