Researchers have developed a dental floss pick capable of measuring salivary cortisol levels to analyze stress.
Although standard strategies for measuring cortisol levels typically involve blood tests or saliva kits, the new dental floss pairs electropolymerized molecularly imprinted polymers with thread microfluidics to provide noninvasive, real-time results.
Researchers 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,” Atul Sharma, PhD, of Tufts University, Medford, Mass., and colleagues wrote.
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 enzyme-linked immunosorbent assay (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 laboratory-based analysis.
Unlike bulky mouthguard biosensors or tests requiring manual pipetting, the floss system is low-cost, hands-free, and unobtrusive—traits the researchers said 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,” the study authors concluded.
The sensor is currently in prototype form, but the researchers envisioned future adaptations to detect multiple biomarkers for mental health, inflammation, or metabolic conditions.
