An Electrochemical Cortisol Sensor Based on rGO-Modified Molecularly Imprinted Polymers

The growing burden of stress-related mental disorders has intensified the demand for practical tools that enable objective and continuous stress assessment. Cortisol is a well-established biochemical indicator of stress and is detectable in sweat, making it attractive for portable monitoring. In this work, we present a portable electrochemical cortisol sensor (PECS) constructed on a screen-printed carbon electrode, where reduced graphene oxide (rGO) enhances charge transfer and an electropolymerized molecularly imprinted polymer (MIP) provides selective recognition. The PECS delivers reliable quantification from 0.01 to 100 nM with stable signal output, achieving a sensitivity of 670.0 nA·nM−1·cm−2 and a limit of detection of 0.0031 nM (i–t mode). The proposed platform supports non-invasive, real-time cortisol readout and offers a feasible route toward soft bioelectronic systems for mental-health-oriented monitoring.