Experimental and finite element method studies for femtomolar cobalt ion detection using a DHI modified nanochannel

In this work, a sensing nanochannel based on a N-[3-(triethoxysilyl)propyl]-4,5-dihydroimidazole (DHI) modified nanopipette was prepared and characterized for the ultrasensitive detection of cobalt ions (Co²⁺) in aqueous solutions. By both experimental and theoretical studies, the detection conditions (chelation balance time, pH of the electrolyte, nanopipette diameter, potentials for ionic current) and parameters (rectification value, resistance and ionic current) have been fully optimized, and the proposed Co²⁺ sensor shows a significantly wide detection range from 20 fM to 0.2 mM, with an ultra-low detection limit down to 0.94 fM.