Redesigning an Electrochemical MIP Sensor for PFOS: Practicalities and Pitfalls

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Science

Background:

• Growing demand for portable electrochemical sensors for in situ environmental contaminant monitoring.
• Technological transfer of sensors requires consideration of various parameters, including electrode surface properties.
• Molecularly imprinted polymer (MIP) sensors offer high performance but need careful optimization during redesign.

Purpose of the Study:

• To investigate the poor performance of a redesigned MIP electrochemical sensor for perfluorooctanesulfonic acid (PFOS) on screen-printed electrodes.
• To characterize the electrode surfaces and polymer distribution before further sensor optimization.
• To establish a comprehensive characterization protocol for similar sensor redesign projects.

Main Methods:

• Redesign of a PFOS-MIP sensor from gold disk to gold screen-printed electrodes.
• Morphological analysis using Scanning Electron Microscopy-Energy-Dispersive X-ray Spectrometry (SEM-EDS).
• Surface characterization via Atomic Force Microscopy (AFM) and profilometry.
• Electrochemical performance evaluation using differential pulse voltammetry.

Main Results:

• The redesigned sensor exhibited poor electrochemical performance.
• SEM-EDS, AFM, and profilometry revealed heterogeneous polymer distribution on the screen-printed electrodes.
• Electrode surface roughness was identified as a critical factor influencing polymer morphology.
• A method to map polymer distribution using the fluorine content of the PFOS molecule was developed.

Conclusions:

• Electrode surface roughness significantly influences the performance of MIP electrochemical sensors.
• A multi-analytical characterization approach is crucial for understanding and optimizing sensor redesign.
• The developed characterization protocol can guide future efforts in developing robust portable analytical devices.