Ultrafast humidity-responsive structural colors from disordered nanoporous titania microspheres

2019 ◽  
Vol 7 (17) ◽  
pp. 10561-10571 ◽  
Author(s):  
Syazwani Mohd-Noor ◽  
Hansol Jang ◽  
Kyungnae Baek ◽  
Yi-Rong Pei ◽  
Al-Mahmnur Alam ◽  
...  
Keyword(s):  
Response Times ◽  
Water Molecules ◽  
Humidity Sensors ◽  
Structural Colors ◽  
Titania Microspheres ◽  
Monolayer Coverage

Ultrafast and reversible colorimetric responses to humidity changes are observed with disordered, nanoporous titania microspheres, optimized in speed and intensity with a monolayer coverage. The response times, defined by intracrystalline diffusion of water molecules, represent the fastest values for colorimetric humidity sensors.

Capacitive Humidity Sensors With High Sensitivity and Subsecond Response Times

2007 ◽  
Vol 7 (6) ◽  
pp. 955-956 ◽  
Author(s):  
John J. Steele ◽  
Glen A. Fitzpatrick ◽  
Michael J. Brett
Keyword(s):  
Response Times ◽  
High Sensitivity ◽  
Humidity Sensors

Nanostructured Oxide Films for High-Speed Humidity Sensors

2003 ◽  
Vol 788 ◽  
Author(s):  
John J. Steele ◽  
Kenneth D. Harris ◽  
Michael J. Brett
Keyword(s):  
Thin Film ◽  
High Speed ◽  
Response Times ◽  
Glancing Angle Deposition ◽  
Multiple Response ◽  
Humidity Sensors ◽  
Advanced Technique ◽  
Glancing Angle ◽  
Nanostructured Oxide ◽  
Angle Deposition

ABSTRACTMiniaturized thin film humidity sensors were fabricated using nanostructured materials deposited by an advanced technique known as glancing angle deposition (GLAD). These sensors exhibited extremely fast desorption response times of less than 40 ms to steplike changes in humidity. Multiple response time measurements for various initial humidities have shown that the sensors maintain their rapid response at all levels of humidity.

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 Solid State Humidity Sensors

2021 ◽  
Author(s):  
Rajesh Kumar
Keyword(s):  
Solid State ◽  
Thick Film ◽  
Response Times ◽  
Humidity Sensors ◽  
Humidity Sensing ◽  
Humidity Measurement ◽  
Film Preparation

A variety of humidity sensors have been developed to address the problem of humidity measurement in instrumentation, agriculture and systems which are automatic. Various types of humidity sensors have been reviewed along with their mechanisms of humidity detection. Thin and thick film preparation processes are quite flexible. This flexibility provides advantages over other technologies. After comparing all the aspects of different humidity sensors, it has been observed that there are still some shortcomings left, which need to be removed to enhance the humidity sensing capability, recovery and response times of the sensor elements.

scholarly journals Effects of pH on High-Performance ZnO Resistive Humidity Sensors Using One-Step Synthesis

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5267 ◽  
Author(s):  
Yu ◽  
Zhang ◽  
Zhang ◽  
Li
Keyword(s):  
High Performance ◽  
Oxygen Vacancies ◽  
Humidity Sensor ◽  
Ph Value ◽  
Precursor Solution ◽  
Hydroxyl Group ◽  
Water Molecules ◽  
Hydroxyl Groups ◽  
Humidity Sensors ◽  
One Step

In this paper, we prepared a high-performance zinc oxide (ZnO) humidity sensor in an alkaline environment using one-step hydrothermal method. Experiments showed that the pH value of the precursor solution affects the performance of ZnO humidity sensors. There are abundant hydroxyl group and oxygen vacancies on the surface of ZnO with a precursor pH value of 10. Abundant hydroxyl groups on the surface of ZnO can adsorb a large number of water molecules and rich oxygen vacancies can accelerate the decomposition of water molecules, thus increasing the number of conductive ions (H3O+) and further improving the performance of the sensor. So, such a ZnO humidity sensor exhibited high sensitivity (14,415), good linearity, small hysteresis (0.9%), fast response/recovery time (31/15 s) in the range from 11% to 95% relative humidity (RH). Moreover, the ZnO-2 humidity sensor has good repeatability and can be effectively used for a long time. This study provides a new idea for the development of low-cost, high-performance and reusable ZnO resistive humidity sensors.

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

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1623
Author(s):  
Wang-De Lin ◽  
You-Chen Lin ◽  
Ren-Jang Wu ◽  
Murthy Chavali
Keyword(s):  
Raman Spectroscopy ◽  
Zinc Oxide ◽  
Humidity Sensor ◽  
Response Times ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Atmospheric Humidity ◽  
Humidity Sensors ◽  
Structure And Morphology ◽  
Recovery Times

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.

scholarly journals Capacitance and Resistivity Measurements of Polythiophene /Metallic Nanoparticles-based Humidity Sensors

2021 ◽  
pp. 1158-1163
Author(s):  
Estabraq Talib Abdullah ◽  
Omar A. Ibrahim
Keyword(s):  
Indium Tin Oxide ◽  
Metallic Nanoparticles ◽  
Room Temperature ◽  
Response Times ◽  
Active Material ◽  
Scanning Electron Micrographs ◽  
Electrical Characteristics ◽  
Humidity Sensors ◽  
Humidity Level ◽  
Resistivity Measurements

Capacitive–resistive humidity sensors based on polythiophene (P3HT) organic semiconductor as an active material hybrid with three types of metallic nanoparticles (NP) (Ag, Al, and Cu) were synthesized by pulsed laser ablation (PLA). The hybrid P3HT/metallic nanoparticles were deposited on indium-tin-oxide (ITO) substrate at room temperature. The surface morphology of theses samples was studied by using field emission scanning electron micrographs (FE-SEM), which indicated the formation of nanoparticles with grain size of about 50nm. The electrical characteristics of the sensors were examined as a function of the relative humidity levels. The sensors showed an increase in the capacitance with variation in the humidity level.  While the resistivity While the resistivity decrease nonlinearity in the variation of humidity level from 10% to 100%.. The results show that the recovery and response times were higher for the Al/P3HT/Cu/Al sensor compared with those of the other nanoparticles.   

Effects of graphene layer and gold nanoparticles on sensitivity of humidity sensors

2020 ◽  
Vol 3 (1) ◽  
pp. 20-27
Author(s):  
Jiawei Bao ◽  
Niloofar Hashemi ◽  
Jingshuai Guo ◽  
Nicole N. Hashemi
Keyword(s):  
Gold Nanoparticles ◽  
Relative Humidity ◽  
Graphene Layer ◽  
Humidity Sensor ◽  
Response Times ◽  
Humidity Sensors ◽  
Micro Electro Mechanical Systems ◽  
Layer Graphene ◽  
Different Response ◽  
The Relationship

Humidity sensors can be used to monitor body sweat. Here, we studied a humidity sensor that comprised of a graphene layer between two electrodes. The operating principle is that the humidity sensor will respond when vapor reaches the graphene layer from the top. Based on the humidity diffusion, the sensor measures the relative humidity (RH) with different response times. Graphene is a material with high diffusivity and small thickness that can increase the sensitivity of a sensor. Based on the micro electro mechanical systems (MEMS) method, we modeled the humidity sensor using COMSOL Multiphysics® transport of diluted species software. Additionally, we used the concentration values from the simulations to determine the relationship between capacitance and relative humidity. The sensitivity was found to be 3.379 × 10−11 pF/%RH for the 4-layer graphene, 1.210 × 10−14 pF/%RH for the 8-layer graphene, and 3.597 × 10−11 pF/%RH for the 16-layer graphene sensor. The sensitivity of 4-layer graphene with gold sensor is 3.872 × 10−13 pF/%RH which is smaller than 4-layer graphene sensor, and graphene with gold nanoparticles shows better response time than 4-layer graphene sensor.

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