tRemote unattended sensor networks are increasingly sought after to monitor the drinking water dis-tribution grid, industrial wastewater effluents, and even rivers and lakes. One of the biggest challengesfor application of such sensors is the issue of in-field device calibration. With this challenge in mind, wereport here the use of anodic stripping coulometry (ASC) as the basis of a calibration-free micro-fabricatedelectrochemical sensor (CF-MES) for heavy metal determinations. The sensor platform consisted of aphoto-lithographically patterned gold working electrode on SiO2substrate, which was housed within acustom stopped-flow thin-layer cell, with a total volume of 2–4 L. The behavior of this platform wascharacterized by fluorescent particle microscopy and electrochemical studies utilizing Fe(CN)63−/4−as amodel analyte. The average charge obtained for oxidation of 500 M ferrocyanide after 60 s over a 10month period was 176 C, corresponding to a volume of 3.65 L (RSD = 2.4%). The response of the platformto copper concentrations ranging from 50 to 7500 ppb was evaluated, and the ASC results showed a lineardependence of charge on copper concentrations with excellent reproducibility (RSD ≤ 2.5%) and accuracyfor most concentrations (≤5–10% error). The platform was also used to determine copper and mercurymixtures, where the total metallic content was measurable with excellent reproducibility (RSD ≤ 4%) andaccuracy (≤6% error).