Textile-Integrated Organic Electrochemical Transistor for Selective Ion Detection via Electrical Impedance Spectroscopy

In this letter, we present a novel approach for the fabrication of a fully printed poly(3,4 ethyldioxythiophene)poly(styrenesulfunate)-based organic electrochemical transistor (OECT) on textile substrates, that serves as a selective cation sensor, thanks to the combination of both OECT and electrochemical impedance spectroscopy (EIS) response. In particular, the selectivity achieved relies on discerning ion diffusion dynamics at low frequencies during EIS measurements and coupling these with the variations in OECT response associated with ion concentration. Unlike existing literature, our sensor is fabricated using cost-effective techniques, is planar, integrated directly onto textiles, and operates without external gate electrodes. Employing the same device configuration for both OECT and EIS measurements (both methods with a high coefficient of correlation
$R^{2} = 89\%$
and
$R^{2} > 94\%$
, respectively), we demonstrate its efficacy by characterizing the sensor across three different concentrations of potassium chloride and sodium chloride, establishing a comprehensive 3-D calibration space to extract the electrolyte composition in a concentration between 1.25 and 100 mM.