A Microfluidic Chip Integrated With a Carbon Nanotube-Polydimethylsiloxane Electrode Array for Simultaneous Detection of Cd2+, Pb2+, and Hg2+

The reliably and sensitively simultaneous tracking of multiple heavy metal ions in human serum is still a challenge. Hence, a microfluidic chip integrated with a carbon nanotube-polydimethylsiloxane (CNT-PDMS) electrode array was developed to detect various heavy metal ions. To improve electrochemical activity and the reactive site number of the electrode, the bismuth nanoparticles (BiNPs) were electrodeposited onto the surface of the CNT-PDMS. To enhance the reproducibility of the electrode, a gelatin-glutaraldehyde cross-linking hydrogel film (GLT-CNT-GTA) was introduced. Simultaneous detection of Cd2+, Pb2+, and Hg2+ can be measured with high sensitivity (1728.5, 1332.7, and 2111.3 nA/nM), low detection limit (3.75, 0.49, and 2.91 nM). Furthermore, shelf-life investigation over 20 days, the measurement signals of the electrode in microfluidic device still maintain 88.23%, 89.93%, and 90.88%, respectively, for Cd2+, Pb2+, and Hg2+ detection. This platform demonstrates the potential application in simultaneous detection of Cd2+, Pb2+, and Hg2+ in human serum.