Oil-Membrane Protection of Electrochemical Sensors for Fouling-and pH-Insensitive Detection of Lipophilic Analytes

To take full advantage of the reagent-and label-free sensing capabilities of electrochemical sensors, a frequent and remaining challenge is interference and degradation of the sensors due to uncontrolled pH or salinity in the sample solution or foulants from the sample solution. Here, we present an oil membrane sensor protection technique that allows for the permeation of hydrophobic (lipophilic) analytes into a sealed sensor compartment containing ideal salinity and pH conditions while simultaneously blocking common hydrophilic interferents (proteins, acids, bases, etc.) In this paper, we validate the oil membrane sensor protection technique by demonstrating continuous cortisol detection via electrochemical aptamer-based (EAB) sensors. The encapsulated EAB cortisol sensor exhibits a 5 min concentration-on rise time and maintains a measurement signal of at least 7 h even in the extreme condition of an acidic solution of pH 3.

Automated summary

This paper presents an oil membrane sensor protection technique to prevent interference and degradation of electrochemical sensors due to uncontrolled pH, salinity, or foulants in sample solutions. The technique allows for the permeation of hydrophobic analytes while blocking common hydrophilic interferents, demonstrating continuous cortisol detection with a 5 min concentration-on rise time and maintaining signal measurement for at least 7 h even in extreme acidic conditions.