PANI and PPy-Based Biosensing of Salt Stress in Plants: An Electrochemical Approach

Organic electrochemical transistor (OECT)-based biosensors fabricated from two different conducting polymer composite materials, carbon black/polyaniline and carbon black/polypyrrole have been demonstrated for direct, real-time, in-vivo monitoring of salt stress in plants. Similar in-vivo monitoring of salt stress in plants was also done by means of OECT-based biosensor fabricated from the conducting polymer Poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT: PSS) and a comparison has been drawn between the three types of biosensor. Electrochemical Impedance Spectroscopy studies were done for each biosensor in order to understand the dependence of its channel current on its control voltage and also to electrically model its channel. When a plant was subjected to salt stress, changes in ionic concentration in its sap were found to modulate channel current of the transistor-based device integrated in the plant. This current modulation was observed at the output of all the three devices, demonstrating the ability of all of them to monitor salt stress.