Improving accuracy and reliability of an electrochemical impedance spectroscopy aptamer-based biosensor

Impedance -based biosensors are effective tools for rapid and specific detection. However, they often rely solely on charge transfer resistance as an indicator of surface structural changes upon analyte binding and other valuable data are constantly ignored. In this work we explore different data obtained for a biosensor designed for water toxin (Saxitoxin) detection using electrochemical impedance spectroscopy. Both, the signal gain and the relative standard deviation (RSD) were dependent on the potential applied during the measurement. This indicates that the data reading mode can be modulated to favor either the signal or the deviation. The charge transfer resistance (Rct) values with gain up to 18.0 % were obtained, but with RSD higher than 5.0 %. Impressive 39.3 % of signal gain with negligible RSD was found for the real impedance, which is 2.7 -fold higher the values obtained for conventional Rct analysis. Most of the reasonable signals remain at frequencies above 100 Hz, demonstrating that gain at these frequencies tend to be less dispersive. In addition, the relative standard deviation can be reduced by increasing the concentration of the redox probe. The obtained results highlight the importance of carefully selecting parameters for characterizing the electrochemical behavior of the system to identify the most reliable and informative parameters for detection. This research contributes to broader electrochemistry sensing applications, opening new horizons for improving the accuracy and reliability of electrochemical analysis.