Humidity Sensor Based on Graphene Oxide Film Prepared by Simple Drop-Casting Process

In this work, the film of graphene oxide was deposited by drop-casting process for humidity sensor device. The structural property of graphene oxide film was performed by Raman spectroscopy. The humidity device was fabricated onto the indium-tin oxide transparent electrode. The device exhibited the adsorption and desorption behavior of humidity in range of 23-93%RH. The complex impedance measurement was used to explain the mechanisms of the humidity device. The equivalent circuit model of the device has been demonstrated.

Complex Impedance Measurement System for the Frequency Range from 5 kHz to 100 kHz

The improved design of previously developed complex impedance measurement system is described. Realized system for measurement of complex impedance is based on integrated circuit AD5933 which is controlled by microcontroller ATmega128. Device has full standalone capabilities with LCD for displaying of results and keyboard for configuration on the field. Created report with measured values of impedance magnitude and phase angle is stored on micro SD card in format compatible with MS Excel which ensures easy off-line analysis on PC. Realized device is equipped with self-calibration system which ensures high accuracy in wide range of impedance and frequency. In the aim of the verification of developed system, the measurement results are plotted and compared with theoretical impedance values. Realized system can be used for complex impedance measurement, impedance spectrometry, biomedical and automotive sensors, proximity sensors, FFT processing, structural health monitoring, etc.