A portable wireless‐sensor system from all‐in‐one sensor array based hybrid solid contact layer for point‐of‐care ion monitoring in river basin

Abstract The sensor arrays are considered as a promising way to aim at point‐of‐care (POC) testing for the detection of different ions in environment through the use of solid‐contact ion‐selective electrodes (SC‐ISEs). However, the exorbitant equipment and intricate process for the production of SC‐ISEs arrays has limit its application. Herein, the Au with nano‐branched structure (Au NBS) and poly (3,4‐ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT : PSS) were decorated on the surface of bare pad of traditional printed circuit boards coated with Au (Au‐PCB) to construct a hybrid solid‐contact layer including double‐layer capacitance and pseudocapacitance of SC‐ISEs synergistically, thus the multichannel SC‐ISEs exhibited high stability and specificity. Overall, based on portable multichannel sensor and homemade APP (Ion Analysis), a wireless all‐in‐one sensor system was constructed to detect ions with the limit of NO 3 − , Cl − , Na + , K + , Ca 2+ and Mg 2+ as 0.047 mM, 0.039 mM, 0.022 mM, 0.066 mM, 0.045 mM and 0.024 mM, respectively. Besides, it can detect such ions in river basin successfully. With the cost of each electrode less than 0.5 $, this sensor arrays enable a wide range of hazardous ion monitoring in water environment.