CMOS Compatible, Low Power, High-Sensitivity Zn/Al Layered Double Hydroxides Humidity Micro-Sensor

After depositing on glass substrates aluminum thin film micro-patterned tracks, we have used a wet chemistry process in order to transform the aluminum metal into Zn/Al layered double hydroxides (LDHs). This technique consists in placing the substrates into a zinc nitrate solution with a basic agent at temperatures lower than 90 °C. Such a hydrothermal method is very simple, low cost, CMOS/MEMS compatible, suitable for large area substrates and results in the growth of Zn/Al LDHs thin films with nanoplatelets shape. We have then tested the nanostructured Zn/Al LDH micro-sized tracks as a humidity sensor and found a high sensitivity at room temperature. Our approach seems ideal for the fabrication of CMOS-compatible, low power, on-chip integrated humidity micro-sensors.