Ultrafast Humidity Sensing by Anisotropic Deformation of Carbon Nitride Nanoribbons for Real-Time Respiratory Monitoring

Developing humidity sensing materials with fast response and high sensitivity was of great interest for many applications from industrial field to human healthcare. Here, we report a carbon nitride nanoribbons (CNNRs)-based humidity sensor. Thanks to the delicate humidity-responsive anisotropic deformation and well-balanced hydrophilic surfaces/hydrophobic framework with rapid adsorption/desorption of water molecules by CNNRs, this humidity sensor possessed an ultrafast response of ca. 50 ms, high reproducibility and selectivity, and linearity in an almost full humidity range. As an example, this sensor was successfully applied to real-time breathing detection, and the as-obtained breathing graphic waveforms exhibited a higher sensitivity than that by the traditional clinic measurements. This work would pave a new way for ultrafast and sensitive humidity sensing by using anisotropic deformation of CNNRs and introduce a new application scheme of humidity sensors in more user-friendly respiratory monitoring with higher resolution.<br>

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

Nanomaterials ◽

10.3390/nano11123368 ◽

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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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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A Full-Range Flexible and Printed Humidity Sensor Based on a Solution-Processed P(VDF-TrFE)/Graphene-Flower Composite

Nanomaterials ◽

10.3390/nano11081915 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1915

Author(s):

Shenawar Ali Khan ◽

Muhammad Saqib ◽

Muhammad Muqeet Rehman ◽

Hafiz Mohammad Mutee Ur Rehman ◽

Sheik Abdur Rahman ◽

...

Keyword(s):

Active Layer ◽

Humidity Sensor ◽

High Reliability ◽

Full Range ◽

High Sensitivity ◽

Fast Response ◽

Considerable Change ◽

Relative Humidity Range ◽

Response And Recovery ◽

Proportional Relationship

A novel composite based on a polymer (P(VDF-TrFE)) and a two-dimensional material (graphene flower) was proposed as the active layer of an interdigitated electrode (IDEs) based humidity sensor. Silver (Ag) IDEs were screen printed on a flexible polyethylene terephthalate (PET) substrate followed by spin coating the active layer of P(VDF-TrFE)/graphene flower on its surface. It was observed that this sensor responds to a wide relative humidity range (RH%) of 8–98% with a fast response and recovery time of 0.8 s and 2.5 s for the capacitance, respectively. The fabricated sensor displayed an inversely proportional response between capacitance and RH%, while a directly proportional relationship was observed between its impedance and RH%. P(VDF-TrFE)/graphene flower-based flexible humidity sensor exhibited high sensitivity with an average change of capacitance as 0.0558 pF/RH%. Stability of obtained results was monitored for two weeks without any considerable change in the original values, signifying its high reliability. Various chemical, morphological, and electrical characterizations were performed to comprehensively study the humidity-sensing behavior of this advanced composite. The fabricated sensor was successfully used for the applications of health monitoring and measuring the water content in the environment.

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

Materials Chemistry Frontiers ◽

10.1039/c8qm00596f ◽

2019 ◽

Vol 3 (3) ◽

pp. 484-491 ◽

Cited By ~ 9

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.

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

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.562-565.344 ◽

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.

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