Novel Chemoresistive Sensor for Sensitive Detection of Pb²⁺ Ions Using an Interdigital Gold Electrode Fabricated with...

This study presents novel chemoresistive reduced graphene oxide-ion-imprinted polymer (IIP-rGO)-based sensors for detection of lead (Pb²⁺) ions. The ion-imprinted polymer was synthesized by bulk polymerization and modified with a variable amount of rGO incorporated to form an IIP-rGO composite. The amount of rGO in the polymer matrix affected the sensor's relative response, and 1:3 mass ratio produced excellent results, with a consistent trend as the concentration of Pb²⁺ ions increased in the solution. The decrease in relative resistance (ΔR/R _o) followed an exponential decay relationship between the ΔR/R _o response and the concentration of Pb²⁺ ions in aqueous solutions. After solving the exponential decay function, it is observed that the sensor has the upper limit of ΔR/R _o >1.7287 μg L^-1, and the limit of detection of the sensor is 1.77 μg L^-1. A nonimprinted polymer (NIP)-based sensor responded with a low relative resistance of the same magnitude although the concentration was varied. The response ratio of the IIP-based sensor to the NIP-based sensor (ΔR/R _o)_IIP/(ΔR/R _o)_NIP as a function of the concentration of Pb²⁺ ions in the solution shows that the response ratios recorded a maximum of around 22 at 50 μg L^-1 and then decreased as the concentration increased, following an exponential decay function with the minimum ratio of 2.09 at 200 μg L^-1 but never read 1. The sensor showed excellent selectivity against the bivalent cations Mn²⁺, Fe²⁺, Sn²⁺, and Ti²⁺. The sensor was capable of exhibiting 90% ΔR/R _o response repeatability in a consecutive test.