Abstract: A solid-state nanopore system includes a single-molecule chip that works on the principle of pore occlusion by the detected molecule, which then can be registered as a change in ionic current. Low-noise and low-capacitance glass chips are used with ultrathin (<20 nm) silicon nitride (SiN) nanopores of 1.5-5 nm diameter and a miniaturized nanopore reader are used as the nanopore sensor, which is capable of sensing the presence of mercury ion (Hg2+) and lead ion (Pb2+) at concentrations down to 0.5 nM and 5 nM, respectively. Detectable distinct electrical translocation characteristics between the two metal ions were enabled by short DNA molecules (aptamers) functioning as a carrier, binding via specific interactions with the metal ions to provide a selective nanopore sensor for water monitoring by identification of electrical fingerprints of the respective ions.