Epitaxial Graphene Sensors Combined with 3D-Printed Microfluidic Chip for Heavy Metals Detection
Maria Francesca Santangelo1, Ivan Shtepliuk2, Daniel Filippini3
1Applied Sensors Science, Department of Physics, Chemistry, and Biology-IFM, Linköping University, S-58183 Linköping, Sweden. maria.francesca.santangelo@liu.se.
Sensors (Basel, Switzerland)
|May 28, 2019
Summary
Epitaxial graphene on silicon carbide shows promise for detecting heavy metals like lead and cadmium in liquids. This new sensor platform offers fast, stable, and sensitive detection, crucial for environmental monitoring.
Area of Science:
- Materials Science
- Environmental Science
- Nanotechnology
Background:
- Heavy metal contamination poses significant environmental and health risks.
- Developing sensitive and selective detection methods is crucial for monitoring pollutants.
- Epitaxial graphene (EG) on silicon carbide (SiC) is a promising material for sensor applications due to its unique electronic properties.
Purpose of the Study:
- To investigate the sensing performance of epitaxial graphene on Si-face 4H-SiC (EG/SiC) for the liquid-phase detection of heavy metals, specifically lead (Pb) and cadmium (Cd).
- To develop and utilize a 3D-printed microfluidic device integrated with EG/SiC for lab-on-chip (LOC) heavy metal analysis.
- To elucidate the sensing mechanisms and preferential binding of heavy metal ions on EG.
Main Methods:
- Fabrication of a sensing platform using 3D-printed microfluidic devices incorporating EG/SiC.
- Conductometric measurements of EG/SiC sensors exposed to varying concentrations of Pb2+ and Cd2+ solutions.
- Computational analysis including van-der-Waals (vdW)-corrected density functional theory (DFT), non-covalent interaction (NCI) analysis, extended charge decomposition analysis (ECDA), and topological analysis.
- Electrochemical measurements to confirm conductometric findings.
Main Results:
- EG/SiC demonstrated fast and stable responses with a low detection limit for Pb and Cd ions.
- A Langmuir correlation was observed between the sensor signal and Pb2+ concentrations (125 nM to 500 µM).
- The sensor response was dominated by Pb2+ in the presence of both metals, indicating preferential binding.
- DFT calculations and NCI analysis revealed that Pb2+ and Cd2+ act as electron acceptors, enhancing EG conductivity via charge transfer, with Pb2+ showing stronger binding affinity.
- Electrochemical tests confirmed EG's higher sensitivity to lead than cadmium.
Conclusions:
- EG/SiC is a highly effective material for sensitive and selective liquid-phase detection of heavy metals like lead and cadmium.
- The 3D-printed microfluidic platform enables efficient lab-on-chip (LOC) heavy metal analysis.
- The preferential sensing of lead over cadmium is attributed to stronger Pb2+ binding with graphene, supported by theoretical calculations.
- This technology holds potential for environmental monitoring and water quality assessment.
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