Proton transport over nanoparticle surface in insulating nanoparticle film-based humidity sensor

Author(s):  
Shinya Kano ◽  
Harutaka MEKARU

Abstract We study a proton transport on the surface of insulating nanoparticles for humidity sensors. We use the approach to reveal proton transfer mechanisms in humidity sensitive materials. Hydrophilic and hydrophobic ligand-terminated silica nanoparticle films are adopted for evaluating temperature dependence of the ion conductivity. According to the activation energy of the conductivity, we explain the Grotthuss (H+ transfer) and vehicular (H3O+ transfer) mechanisms are mainly dominant on hydrophilic (-OH terminated) and hydrophobic (acrylate terminated) surface of nanoparticles, respectively. This investigation gives us a clue to understand a proton transfer mechanism in solution-processed humidity-sensitive materials such as oxide nanomaterials.

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3858
Author(s):  
Shinya Kano ◽  
Harutaka Mekaru

Fast-response humidity sensors using nanomaterials are attractive and have been intensively studied. Among the various nanomaterials, nonporous inorganic nanoparticles are suitable for use in humidity sensitive films for sensors. Here, we focus on a nonporous inorganic nanoparticle film and investigate a humidity sensor using the film. Hysteresis error and a dynamic response to a change of humidity are fundamental specifications of humidity sensors. A humidity sensor using a 50 nm silica nanoparticle film shows a hysteresis error of 2% at 85% RH and a response/recovery time of 2.8/2.3 s in 30% RH to 70% RH. We also summarize response/recovery times and hysteresis errors of state-of-the-art humidity sensors. As compared to those of commercial sensors and porous nanoparticle-based sensors evaluated using saturated salt solutions, the fabricated sensor shows a comparative hysteresis error and shorter response time.


2017 ◽  
Vol 53 (32) ◽  
pp. 4465-4468 ◽  
Author(s):  
Yuan Gao ◽  
Pengtao Jing ◽  
Ning Yan ◽  
Michiel Hilbers ◽  
Hong Zhang ◽  
...  

Combined photoluminescence and impedance spectroscopy studies show that a europium-based metal–organic framework behaves as a highly effective and reliable humidity sensor, enabling dual-mode humidity detection.


Nanoscale ◽  
2014 ◽  
Vol 6 (12) ◽  
pp. 6521-6525 ◽  
Author(s):  
Ming Zhuo ◽  
Yuejiao Chen ◽  
Tao Fu ◽  
Haonan Zhang ◽  
Zhi Xu ◽  
...  

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.


2018 ◽  
Vol 15 ◽  
pp. 207-212 ◽  
Author(s):  
Byung Il Choi ◽  
Sang-Wook Lee ◽  
Sang-Bong Woo ◽  
Jong Chul Kim ◽  
Yong-Gyoo Kim ◽  
...  

Abstract. Accurate measurements of temperature and water vapor in the upper-air are of great interest in relation to weather prediction and climate change. Those measurements are mostly conducted using radiosondes equipped with a variety of sensors that are flown by a balloon up to lower stratosphere. Reference Upper Air Network (GRUAN) has identified water vapor pressure as one of the most important measurands and has set an accuracy requirement of 2 % in terms of the mixing ratio. In order to achieve the requirement, many errors in the humidity measurement such as a temperature dependency in sensing characteristics including measurement values and response time need to be corrected because humidity sensors of radiosondes pass through low-pressure (1 kPa) and low-temperature (−80 ∘C) environments in the upper-air. In this paper, the humidity sensing characteristics of Jinyang radiosonde sensors in relation to temperature dependencies were evaluated at low temperature using a newly developed ultralow-temperature humidity chamber. The sensitivity characteristic curve of the radiosonde sensors was evaluated down to −80 ∘C, and the calibration curves of the humidity sensor and the temperature sensor were obtained. The response time of humidity sensor slowly increased from 52 to 116 s at the temperature from 20 to −40 ∘C, respectively, and then rapidly increased to almost one hour at −80 ∘C. Those results will help to improve the reliability of the upper-air observation data.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Anabel Renteria ◽  
Luisa F. Garcia ◽  
Jorge A. Diaz ◽  
Luis C. Delfin ◽  
Jaime E. Regis ◽  
...  

Purpose The purpose of this study is to evaluate different 3D structures for humidity sensing that will enable the fabrication of complex geometries with high moisture sensitivity. Design/methodology/approach Humidity sensors based on alumina ceramics were fabricated using direct ink write (DIW) technique. Different engineered surface area, polymer binder ratio and post-processing treatment were considered to increase moisture sensitivity. Findings It was found that the binder ratio plays an important role in controlling the rheology of the paste during printing and determining the pore size after post-processing treatment. The sensibility of the fabricated humidity sensor was investigated by measuring its capacitance response toward relative humidity (RH) varying from 40% to 90% RH at 25°C. It is shown that using 3D lattice design, printed alumina humidity sensor could improve sensitivity up to 31.6 pF/RH%, over an order of magnitude higher than solid alumina. Originality/value Most of the alumina humidity sensors available are films in nature because of manufacturing difficulties, which limited its potential of higher sensitivity, and thus broader applications. In this paper, a novel 3D alumina humidity sensor was fabricated using DIW 3D printing technology.


2020 ◽  
Vol 54 (1) ◽  
pp. 232-241
Author(s):  
Hulin Tai ◽  
Shun Hirota ◽  
Sven T. Stripp

Sensors ◽  
2019 ◽  
Vol 19 (21) ◽  
pp. 4607 ◽  
Author(s):  
Yaqin He ◽  
Mengyao Zhang ◽  
Nan Zhang ◽  
Danrong Zhu ◽  
Chun Huang ◽  
...  

Humidity sensors are indispensable for various electronic systems and instrumentations. To develop a new humidity sensing mechanism is the key for the next generation of sensor technology. In this work, a novel flexible paper-based current humidity sensor is proposed. The developed alternating current electroluminescent devices (ACEL) consist of the electroless plating Ni on filter paper and silver nanowires (AgNWs) as the bottom and upper electrodes, and ZnS:Cu as the phosphor layer, respectively. The proposed humidity sensor is based on ACEL with the paper substrate and the ZnS:Cu phosphor layer as the humidity sensing element. The moisture effect on the optical properties of ACELs has been studied firstly. Then, the processing parameters of the paper-based ACELs such as electroless plated bottom electrode and spin-coated phosphor layer as a function of the humidity-sensitive characteristics are investigated. The sensing mechanism of the proposed sensor has been elucidated based on the Q ~ V analysis. The sensor exhibits an excellent linearity ( R 2 = 0.99965 ) within the humidity range from 20% to 90% relative humidity (RH) and shows excellent flexibility. We also demonstrate its potential application in postharvest preservation where the EL light is used for preservation and the humidity can be monitored simultaneously through the current.


2013 ◽  
Vol 73 (3) ◽  
pp. 613-618 ◽  
Author(s):  
Takashi Kawahara ◽  
Akira Yuuki ◽  
Kumi Hashimoto ◽  
Kazuhiro Fujiki ◽  
Takeshi Yamauchi ◽  
...  

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