Microfluidic Electrochemical Sensor for Heavy Metal Detection Using Pyrolytic Carbon Electrodes and Valveless Micropump*

Abstract

This paper reports, for the first time, the use of pyrolyzed KMPR photoresist to form carbon sensors for detection of trace heavy metals using anodic stripping voltammetry. Shown in this report is its integration with a valveless micropump. This sensor can be used to detect ions of almost any heavy metal in an aqueous solution due to its low overpotential, preventing production of hydrogen. It achieves continuous, real-time measurements. Bismuth ions are added, and the concentration is optimized to enhance sensitivity. The limit of detection of lead ions is 40 ppt under a steady mass flow rate of 10 mL/h. Compared with traditional heavy metal sensors, this microfluidic carbon sensor reduces the limit of detection by three orders. Use of it with a valveless micropump doubles its sensitivity. This doubling is due to fast mass transfer effected by the unsteady valveless micropump flow.