Fast Fourier-Transform Impedance Spectroscopy Applied to Electrochemical Sensors

Abstract

We show that using fast Fourier transform electrochemical impedance spectroscopy (FFT-EIS) to interrogate electrochemical aptamer-based biosensors leads to improved (here better than 2 s) time resolution and calibration-free operation, even when such sensors are deployed in vivo. Because this approach uses the heterogeneous electron transfer rate constant as a means of monitoring target concentration, rather than absolute current, it is independent of both sensor-to-sensor fabrication variation and the drift arising due to fouling in biological fluids, rendering the technique suitable for performing calibration-free in vivo measurements. To showcase these benefits, we demonstrate the approach’s ability to perform real-time molecular measurements in the veins of living rats.