A new wearable sensor disguised as a dental floss pick can measure stress levels in just over ten minutes by detecting cortisol in saliva, researchers from Tufts University report. The device – an electropolymerized molecularly imprinted polymer (eMIP) sensor embedded in a floss handle – offers a sensitive, real-time alternative to conventional cortisol tests that require blood samples or complex saliva kits.
The team, led by Sameer Sonkusale and Atul Sharma, developed the point-of-care platform to facilitate effortless, routine stress monitoring as part of daily dental hygiene. “We posit a ‘what-if scenario’ where dental floss design can automatically provide a salivary cortisol measurement without engaging the subject under test,” the authors write.
Cortisol, a key stress biomarker, diffuses from blood into saliva, making it an attractive target for noninvasive monitoring. The flossing thread collects saliva, which is wicked via capillary action to a flexible graphene-based electrochemical sensor. The sensor’s polymer matrix contains molecular “memory sites” for cortisol, created through electropolymerization of pyrrole in the presence of the hormone. Upon rebinding, cortisol disrupts redox cycling of embedded Prussian Blue, altering the current measured by chronoamperometry and enabling quantification.
The device achieved a detection limit of 0.048 pg/mL in spiked artificial saliva – well below physiological concentrations – and showed strong correlation (r = 0.9910) with conventional ELISA results when tested on real human samples. It also demonstrated high selectivity over structurally similar hormones like cortisone, testosterone, and glucose.
In real-world evaluations, saliva samples were collected from volunteers at various timepoints in a longitudinal stress study and tested both with the floss sensor and ELISA. The platform consistently detected cortisol changes corresponding to stress exposure, matching the accuracy of lab-based analysis.
Unlike bulky mouthguard biosensors or tests requiring manual pipetting, the floss system is low-cost, hands-free, and unobtrusive – traits the researchers say could enhance adherence and compliance in at-home health monitoring. “This platform allowed us to measure subtle changes in salivary cortisol and wireless readout conveniently,” they conclude.
The sensor is currently in prototype form, but the researchers envision future adaptations to detect multiple biomarkers for mental health, inflammation, or metabolic conditions.
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