Uniformly Porous Nanocrystalline CaMgFe1.33Ti3O12 Ceramic Derived Electro-Ceramic Nanocomposite for Impedance Type Humidity Sensor

Abstract

Since humidity sensors have been widely used in many sectors, a suitable humidity sensing material with improved sensitivity, faster response and recovery times, better stability and low hysteresis is necessary to be developed. Here, we fabricate a uniformly porous humidity sensor using Ca, Ti substituted Mg ferrites with chemical formula of CaMgFe1.33Ti3O12 as humidity sensing materials by solid-sate step-sintering technique. This synthesis technique is useful to control the grain size with increased porosity to enhance the hydrophilic characteristics of the CaMgFe1.33Ti3O12 nanoceramic based sintered electro-ceramic nanocomposites. The highest porosity, lowest density and excellent surface-hydrophilicity properties were obtained at 1050 °C sintered ceramic. The performance of this impedance type humidity sensor was evaluated by electrical characterizations using alternating current (AC) in the 33%–95% relative humidity (RH) range at 25 °C. Compared with existing conventional resistive humidity sensors, the present sintered electro-ceramic nanocomposite based humidity sensor showed faster response time (20 s) and recovery time (40 s). This newly developed sensor showed extremely high sensitivity (%S) and small hysteresis of <3.4%. Long-term stability of the sensor had been determined by testing for 30 consecutive days. Therefore, the high performance sensing behavior of the present electro-ceramic nanocomposites would be suitable for a potential use in advanced humidity sensors.

Ultrafast‐Response Humidity Sensor with High Humidity Durability Based on a Freestanding Film of Graphene Oxide Supramolecular

“…Compared with other films for humidity sensing, the as‐fabricated GOA film possessed competitive ultrafast response time in a thicker case, which had more space to improve responsiveness. It can be observed that the response time decreased with decreased thickness for the same type materials, such as the GO‐based films (pink dotted line) and rGO‐based films (blue dotted line) in the figure . In the ultrafast response region marked as yellow, there were three films with the response time smaller than 100 ms. GOA film can maintain ultrafast response at 140 μm thickness, whereas other two films holding ultrafast response were limited to a thickness less than 1 μm.…”

Dielectric and AC conductivity studies of novel porous armalcolite nanocomposite‐based humidity sensor

“…Due to single hydrogen bonding, water molecules move freely and were ionized due to the application of external electric field. As a result, more number of hydronium ions (H 3 O + ) were formed and deposited at the grain and grain‐boundary interface, and thus enhanced the dielectric properties of the composite at higher humid condition …”

“…Moreover, we aimed to design and develop a porous armalcolite nanocomposite‐based humidity sensor in order to analyze their dielectric response at different RH conditions. According to our previous reports, the capacitive and resistive properties of the armalcolite‐based nanocomposite as a function of RH have only been explored until now . In the present work, the RH‐dependent dielectric constant (ɛʹ), ɛʺ, tanδ, alternating current conductivity (σ ac ) along with hysteresis, response time, recovery time, stability and humidity‐sensing mechanism of armalcolite nanocomposite‐based sensor had been studied.…”

“…So far, no study has been done on armalcolite‐based nanocomposite in dielectric‐type humidity sensor applications. In our previous studies, we have developed capacitive‐type and resistive‐type armalcolite‐based nanocomposite ceramics and thin film . Therefore, our present work aims to develop dielectric‐type humidity sensor based on armalcolite ceramic nanocomposite.…”

Polyimide-Based Capacitive Humidity Sensor

“…However, the wide application range of devices being able to record humidity is behind the intensive scientific studies dedicated to this area. Their most important fields of use are indoor application, plants growth in agricultural market, and control of industrial processes, electronics, and semiconductor area, as well as medical processes [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ].…”