Capacitive and resistive response of humidity sensors based on graphene decorated by PMMA and silver nanoparticles

Abstract

In this paper, we reported comparative study of the humidity characteristics of graphene/silver nanoparticles composite (Gr-AgNps) and graphene/silver nanoparticles/PMMA composite (Gr-AgNps-PMMA) based efficient humidity sensors. Aqueous solution of Gr-AgNps and Gr-AgNps-PMMA was drop casted over interdigitated copper electrodes with 50 µm gap embedded in the substrates in dust free environment. The band gap obtained from the UV-vis spectra for Gr-AgNps and Gr-AgNps-PMMA based humidity sensors was 4.7 and 4.1 eV respectively. The capacitive and resistive humidity response was studied using LCR meter (GW Instek817). Apparent increase in capacitance was observed (100-10,000 nF) with the increase in the humidity percentage (30-95 %RH) at lower frequencies for both the sensors. Resistance of the sensors dropped to zero as the humidity level is increased from 30 to 95 %RH in the chamber. The devices were tested for real time stability and for fast response/recovery time. Both the devices showed an excellent stability and response by recording their resistance and capacitance respectively. A lagging of RH decreasing response from RH increasing response was observed at 500 Hz frequency for both the sensors depicted from the hysteresis curve. The humidity response of Gr-AgNps was comparatively better than that of the Gr-AgNps-PMMA based humidity sensors.

Impact of annealing temperature to the performance of hematite based humidity sensor

“…Figure 4 shows Tauc's plot of the hematite nanorod arrays derived using (2). The equation for optical band gap energy estimation is shown (2):…”

“…An ultimate humidity sensor should meet special requirements such as high sensitivity, excellent stability and repeatability, and fast response/recovery rate. Various types of humidity sensors such as capacitive [1] and resistive [2]- [6] were studied for different applications. Among these types, resistive humidity sensor is one of the promising sensors for humidity and vapor detection, based on its simplicity of fabrication process, low cost, and relatively high precision of sensor measurement [7].…”

Effect of Humidity on Gas Sensing Performance of Carbon Nanotube Gas Sensors Operated at Room Temperature

“…The effect of humidity on hydrophilic materials can be macroscopic as well as microscopic while in the hydrophobic materials this effect is only visible microscopically [11]. These effects can cause changes in weight [12], capacitance [13], electrical resistance [14], thermal conductivity [15], crystal frequency [16], etc.…”

High-Performance Humidity Sensor Based on the Graphene Flower/Zinc Oxide Composite

“…Relative humidity sensors can be classified into several types depending on their operation such as resistive, capacitive, impedance, field-effect transistor (FET), optic-fiber, surface acoustic wave (SAW), etc. [ 4 , 5 , 6 ]. Resistive, capacitive, and impedance-based humidity sensors have similar device structure and are commonly used due to their facile fabrication, simplicity of operation, cost-effectiveness, and low driven power [ 5 , 6 , 7 ].…”

“…[ 4 , 5 , 6 ]. Resistive, capacitive, and impedance-based humidity sensors have similar device structure and are commonly used due to their facile fabrication, simplicity of operation, cost-effectiveness, and low driven power [ 5 , 6 , 7 ]. The performance of any type of humidity sensor is strongly dependent on the functional material which can bring good change to its electrical properties with respect to variation in humidity.…”