Flexible Inkjet Printed Ag/rGO/Nafion-Ru(NH3)63+/2+ Two-Electrode Hydrogen Sulfide Sensor for Real-Time Monitoring in Liquids

In this article, we demonstrate real-time hydrogen sulfide monitoring in liquid using a flexible inkjet printed Ag/rGO/Nafion-Ru(NH3)
$_{6}^{3+/2+}$
two-electrode amperometric sensor. The electrodes are inkjet-printed on a flexible substrate, Kapton film, where silver nanoparticles (Ag NPs) are printed as conductive electrodes. The working and reference electrodes (REs) are printed Ag/rGO/Nafion-Ru(NH3)
$_{6}^{3+/2+}$
and Ag/AgCl(s)/PU layers, respectively. The as-printed sensor exhibits a linear sensitivity of 40 nA/
$\mu \text{M}$
/cm2 (
$R= 99.7$
%) and an limit of detection (LoD) of
$0.75~\mu \text{M}$
in the range of 1–
$120~\mu \text{M}$
. The sensor shows the tendency of increase and saturation of the hydrogen sulfide released from cysteine in heating eggs, indicating the effectiveness of the sensor for real-time monitoring.