In an effort to control the super-Nernstian response commonly observed in heavy metal ion determination using microfluidic paper-based solution sampling, researchers turned to metal modified paper-based substrates. In a study, potentiometric responses of Pb2+ion selective electrodes (ISEs) coupled with gold, platinum, and palladium coated paper substrates were analyzed. The researchers found that potentiometric response time was largely dependent on the thickness of the metallic layer deposited on the paper substrate. The team discovered that paper-based substrates coated on both sides with 38 nm gold layers were the most effective at controlling the super-Nernstian response of ISEs in non-equilibrium conditions. Durability studies showed that the lifetime of Pb2+-ISEs could be doubled when used with metal modified paper-based substrates in complex environmental samples with high solid-to-liquid content. In order to validate their method, the researchers determined the concentration of lead in real samples using the metal modified paper substrates coupled with Pb2+-ISEs and confirmed the results using inductively coupled plasma optical emission spectrometry (ICP-OES). The researchers also performed detailed life cycle assessments for model screen printed potentiometric sensors with and without metal modified paper-based solution sampling substrates, and found that the use of modified paper substrates demonstrated lower environmental impact per potentiometric measurement of Pb2+-ISE in prepared simulated environmental samples as compared to sensors without the use of paper substrates. Overall, this study provides insight into the use of metal modified paper substrates to control the super-Nernstian response in heavy metal ion determination and highlights the advantages of using such substrates in terms of controllable response and environmental impact.