Abstract
Humidity detection range is an important indicator for measuring the performance of humidity sensors, but semiconductor humidity sensors often face the problems of narrow detection ranges and insufficient detection sensitivities. In this paper, a magnesium oxide (MgO) humidity sensor based on micro-arc oxidation (MAO) technology was designed to solve these problems by simultaneously using impedance and capacitance as the response signals, as well as by normalizing the output of the two signals. The experimental results showed that the average output of the micro-arc MgO ceramic film, with impedance as the response signal, could reach 150 in the low relative humidity(RH) range (11.3–67% RH), which was much higher than its sensitivity in the high humidity range (< 1), and the film showed fast response (13 s) and recovery (61 s). Under high humidity conditions (67–97.3% RH), with capacitance as the response signal, the output of the micro-arc MgO was as high as 120. Therefore, the micro-arc MgO humidity sensor with impedance, and the sensor with capacitance as the response signal, demonstrated good stability in low humidity and in high humidity environments, respectively, indicating that the method of selecting appropriate response signals for different humidity environments can be applied to extend the humidity detection range of sensing material, and to improve the humidity detection capability of a sensor.
Highlights
Humidity sensors have been widely used in various fields of human production and life, including weather forecasting, health care, and food processing [1,2,3,4,5,6]
→ 600 # → 800 #) was used to grind and remove oil (10% NaOH solution), the magnesium plate was rinsed with deionized water and air-dried for later use
After the printing was completed, the micro-arc oxidation (MAO) plate was held at 80 ◦ C for 1 h to ensure that the silver paste was completely cured to fabricate a micro-arc magnesium oxide (MgO) humidity sensor
Summary
Humidity sensors have been widely used in various fields of human production and life, including weather forecasting, health care, and food processing [1,2,3,4,5,6]. Its faster carrier mobility gives it more potential to develop a humidity sensor with a rapid response [18,19] To this end, this paper is devoted to the use of MAO to grow MgO film layers in situ on the surface of Mg plates to produce humidity sensing material. The micro-arc MgO film layer with impedance and capacitance as the response signals showed a major difference in output, indicating that the method of selecting appropriate response signals for different humidity conditions could be used to extend the humidity detection range of sensing material
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