Rapid and Ultrasensitive Sensor for Point-of-Use Detection of Perfluorooctanoic Acid Based on Molecular Imprinted Polymer and AC Electrothermal Effect

Perfluorooctanoic acid (PFOA) is one of the most persistent and bioaccumulative water contaminants. Sensitive, rapid, and in-field analysis is needed to ensure safe water supplies. Here, we present a single step (one shot) and rapid sensor capable of measuring PFOA at the sub-quadrillion (ppq) level, 4.5 × 10^-4 ppq, within 10 s. This innovative sensor employs a synergistic combination of a molecularly imprinted polymer (MIP)-modified gold interdigitated microelectrode chip and AC electrothermal effects (ACETs), which enhance detection sensitivity by facilitating the accelerated movement of PFOA molecules towards specific recognition sites on the sensing surface. The application of a predetermined AC signal induces microfluidic enrichment and results in concentration-dependent changes in interfacial capacitance during the binding process. This enables real-time, rapid quantification with exceptional sensitivity. We achieved a linear dynamic range spanning from 0.4 to 40 fg/L (4 × 10^-7-4 × 10^-5 ppt) and demonstrated good selectivity (~1:100) against other PFAS compounds, including perfluorooctanoic acid (PFOS), in PBS buffer. The sensor's straightforward operation, cost-effectiveness, elimination of the need for external redox probes, compact design, and functionality in relatively resistant environmental matrices position it as an outstanding candidate for deployment in practical applications.