Summary: Researchers have created a dental-floss-based sensor that detects cortisol, a hormone associated with stress, directly from saliva. The device provides a painless, real-time method for stress monitoring by integrating electropolymerized molecularly imprinted polymers (eMIPs) that selectively recognize cortisol molecules.
With analytical performance comparable to current laboratory biosensors, this floss-based technology could let people monitor stress as easily as part of their daily oral care. The research team is working to adapt the same platform to detect other clinically relevant salivary biomarkers, which could broaden its use for personal health tracking across multiple conditions.
Key Facts:
- Stress Detection: A floss-based electrochemical sensor measures salivary cortisol using molecularly imprinted polymer recognition sites.
- Multi-Marker Potential: The same approach can be adapted to target other salivary biomarkers such as glucose, estrogen, or cancer-related markers.
- Home Use: The device is designed for untrained users, enabling noninvasive, routine stress monitoring at home.
Source: Tufts University
Chronic stress increases the risk of high blood pressure, cardiovascular disease, immune dysfunction, depression, and anxiety.
Current stress assessment methods—self-report questionnaires and clinical evaluations—can be subjective, time-consuming, or costly. To address these limitations, engineers at Tufts developed an easy-to-use dental-floss sensor that measures salivary cortisol quickly and accurately without causing additional stress during measurement.
“This project began as a collaboration across departments at Tufts to study how stress and cognitive states affect problem solving and learning,” said Sameer Sonkusale, professor of electrical and computer engineering. “We did not want the measurement itself to become another source of stress, so we asked whether a sensor could blend into daily routines. Because cortisol is present in saliva, flossing offered a natural, familiar way to collect a sample.”
The device resembles a conventional floss pick: a short plastic handle with two prongs holding a fine thread. Saliva is drawn into the thread by capillary action through a very narrow channel. The fluid travels into the handle and an attached sensing tab where it contacts electrodes that detect cortisol electrochemically.
Selectivity for cortisol is achieved using electropolymerized molecularly imprinted polymers (eMIPs). These polymers are formed around a cortisol template and then the template is removed, leaving nanometer-scale cavities that match the shape and chemical properties of cortisol molecules. In effect, the polymer forms a “cast” that recognizes and binds cortisol from the saliva sample.
Because eMIPs are synthetic and highly tunable, the same fabrication approach can be applied to create floss sensors for other salivary targets such as estrogen for fertility monitoring, glucose for diabetes management, or biomarkers related to cancer and cardiovascular disease. The platform also supports multiplexed detection, enabling simultaneous measurement of multiple markers for a more comprehensive health assessment.
“The eMIP approach changes the game,” Sonkusale said. “Traditional biosensors often rely on antibodies or engineered biological receptors, which require significant development effort. With eMIPs you can rapidly produce a polymer ‘mold’ for a newly identified marker without investing in antibody production.”
Performance of the floss-based cortisol sensor matches the best lab and prototype sensors. Its combination of sensitivity, reliability, and ease of use could bring routine stress monitoring into everyday life and clinical follow-up. Sonkusale and colleagues are forming a startup to commercialize the technology.
The team cautions that saliva-based markers are most valuable for longitudinal monitoring rather than initial diagnosis, since concentrations can vary between individuals. “Blood tests remain the diagnostic gold standard,” Sonkusale noted, “but once a condition is diagnosed, convenient saliva monitoring can help track treatment progress and prompt timely interventions.”
This work builds on prior thread- and textile-based sensor innovations from the research group, including gas sensors, sweat metabolite detectors, movement sensors embedded in clothing, and flexible transistors suitable for wearable electronics.
About this mental health and neurotech research news
Author: Mike Silver
Source: Tufts University
Contact: Mike Silver – Tufts University
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Saliva-Sensing Dental Floss: An Innovative Tool for Assessing Stress via On-Demand Salivary Cortisol Measurement with Molecularly Imprinted Polymer and Thread Microfluidics Integration” by Sameer Sonkusale et al. ACS Applied Materials and Interfaces
Abstract
Saliva-Sensing Dental Floss: An Innovative Tool for Assessing Stress via On-Demand Salivary Cortisol Measurement with Molecularly Imprinted Polymer and Thread Microfluidics Integration
The authors present a dental-floss-based point-of-care platform for noninvasive, real-time quantification of salivary cortisol. The design integrates redox-molecule-embedded molecularly imprinted polymers with thread-based microfluidics and a high-surface-area graphene electrode substrate to synthesize selective cortisol MIPs and build a highly sensitive electrochemical cortisol sensor.
Using flossing to collect and transport saliva by capillary action to a flexible sensor, the platform demonstrated a detection limit as low as 0.048 pg mL–1 and an effective detection range of 0.10–10,000 pg mL–1 (R2 = 0.9916). The system provides results within 11–12 minutes. Thread-based microfluidics reduce interference and improve repeatability for testing artificial and human saliva, yielding recoveries of 98.64–102.4% and a relative standard deviation of 5.01%, indicating high accuracy and precision.
In a human saliva study, the platform correlated strongly with conventional ELISA assays (r = 0.9910). When combined with wireless readout, this saliva-sensing floss offers a practical approach for daily stress monitoring and can be extended to detect a range of salivary biomarkers with high sensitivity and selectivity in complex biological samples.