Cortisol is an accurate biomarker of stress; found abundantly in serum and saliva. Continuous monitoring of cortisol over a span of 24 hours can yield important information on a person’s stress level and endurance. The current gold standards of cortisol analysis are lab centric and not point of care. We present a paper-microfluidic electrochemical sensor specifically designed for cortisol detection from saliva samples.

Graphene electrodes were screen printed on paper along with a layer of Zinc Oxide- metalloporphyrin for enhanced electrochemical detection. The proposed cortisol sensor is based on a competitive binding assay, conducted in a paper reaction site. Response of the sensor was found to a strong linear function of cortisol concentrations in the 50 pM-100 nM range. Limit of detection was found to be as low as 10 pM. The proposed sensing technique was used to detect cortisol levels in clinical saliva samples. In comparison to existing techniques for cortisol detection, our method does not rely on immobilized affinity probes. Rather a magnetic bead based approach has been adopted to deliver the samples to the electrochemical site