Humidity Sensitivity of Chemically Synthesized ZnAl 2 O 4 /Al.

Humidity sensitivity is evaluated for chemically synthesized ZnAl 2 O 4 /Al devices. We succeeded in synthesizing the ZnAl 2 O 4 /Al device by applying chemical techniques only. Hydrothermal treatment for the anodized aluminum (AlO x /Al) gives us the device of the ZnAl 2 O 4 /Al structure. All fabrication processes were conducted under 400 °C. The key was focusing on ZnAl 2 O 4 as the sensing material instead of MgAl 2 O 4 , which is generally investigated as the humidity sensor. The evaluation of this ZnAl 2 O 4 /Al device clarified its effectiveness as a sensor. Both electrical capacitance, C p , and the resistivity, R p , measured by an LCR meter, obviously responded to the humidity with good sensitivity and appreciable repeatability. Our synthesis technique is possible in principle to improve on the process for the device with a complex structure providing a large surface area. These characteristics are believed to expand the application study of spinel aluminate devices as the sensor.