In the contemporary quest to unravel the complexities of human health, stress remains one of the most elusive and impactful factors influencing well-being. Chronic stress is implicated in a host of serious medical conditions, from cardiovascular diseases to compromised immune function, and neuropsychiatric disorders such as depression and anxiety. However, accurately measuring stress levels in real time has long challenged clinicians and researchers alike, hampered by imprecise tools like subjective questionnaires or costly clinical tests. Now, an innovative approach emerging from Tufts University engineers is poised to revolutionize the way we monitor stress, with a deceptively simple but scientifically sophisticated tool: dental floss that senses cortisol in saliva.
Stress biomarkers such as cortisol, a steroid hormone released during the body’s stress response, are pivotal for understanding an individual’s physiological stress load. Traditionally, cortisol measurement involves blood tests or saliva collection using cumbersome sampling methods, which demand clinical expertise and laboratory analysis, making continuous monitoring impractical. The team led by Sameer Sonkusale, a professor of electrical and computer engineering at Tufts, has developed a novel saliva-sensing dental floss that merges microfluidics and molecular imprinting technology, enabling on-demand detection of cortisol as part of daily dental hygiene routines.
The conceptual brilliance of integrating a biosensor into an everyday object like dental floss lies in its seamless incorporation into people’s lifestyles without introducing additional stress. As Sonkusale notes, "We didn’t want measurement to create an additional source of stress, so we thought, can we make a sensing device that becomes part of your day-to-day routine?" With cortisol readily present in saliva, dental floss represents an ideal medium for sample collection — non-invasive, simple to use, and familiar to users worldwide.
Technically, the device resembles an ordinary floss pick, with a taut string stretched between two prongs on a plastic handle roughly the size of an index finger. The saliva drawn between the floss strands travels via capillary action through an ultra-narrow microchannel embedded within the string. From there, the fluid is transported into the handle, where it interacts with precisely engineered electrodes designed to selectively recognize cortisol molecules.
At the heart of this detection system lies the innovative use of electropolymerized molecularly imprinted polymers (eMIPs), a technology dating back nearly three decades but applied here with renewed ingenuity. Molecularly imprinted polymers function akin to molecular “casts”: a polymer matrix is synthesized in the presence of a target molecule — in this case, cortisol — which is then removed, leaving behind cavities that are complementary in shape and chemical functionality. These imprinted sites have a memory that allows them to selectively rebind the target hormone with high affinity and specificity, acting as robust synthetic receptors on the electrode surface.
Unlike traditional biosensors reliant on biological receptors such as antibodies, which can be expensive, fragile, and require complex bioengineering, the eMIP approach offers agility and scalability. This synthetic receptor strategy facilitates rapid development of sensors for new biomarkers simply by creating a polymer mold of the newly identified target molecule. Sonkusale emphasizes the disruptive potential of this method, stating, "If you discover a new marker for stress or any other disease or condition, you can just create a polymer cast in a very short period of time."
The practical applications of this technology extend well beyond stress detection. Because the eMIP molds can be tailored to a variety of salivary biomarkers, this floss-based sensor platform could monitor estrogen levels for fertility tracking, glucose for diabetes management, or other markers linked to cancer and cardiovascular disease. Moreover, the potential exists to engineer multiplexed sensors capable of simultaneously detecting multiple analytes, thereby providing a comprehensive real-time health profile from a single saliva sample.
In their experimental study published in the journal ACS Applied Materials and Interfaces, Sonkusale and colleagues demonstrated that the accuracy of their dental floss cortisol sensors rivals that of the best devices currently available, whether in research settings or commercial development. This level of precision, coupled with the ease of home use without professional training, paves the way toward integrating stress monitoring seamlessly into routine health care, fostering proactive wellness management.
While acknowledging that saliva-based biomarker monitoring is best suited for ongoing assessment rather than initial clinical diagnosis — owing to individual variability in salivary constituents — the researchers highlight its invaluable role in disease management. For example, patients already diagnosed with cardiovascular conditions can use these sensors to track their physiological responses over time, enabling timely interventions and personalized adjustments to treatment regimens.
This pioneering work is part of a broader trajectory of thread- and textile-based sensing technologies developed by Sonkusale’s interdisciplinary team at Tufts. Their portfolio includes sensors integrated into clothing to detect gases, metabolites in sweat, and body movements, as well as flexible electronic devices fabricated entirely from threads. The convergence of these wearable biosensing innovations with the dental floss sensor hints at a future in which seamless, continuous, and non-invasive health monitoring becomes the norm.
A startup company is currently being formed to transition this dental floss sensor from the lab bench to the consumer market, aiming to make stress biomarker monitoring accessible and routine within everyday life. Such commercialization efforts could democratize stress management, empower individuals with actionable data, and ultimately improve public health outcomes at scale.
This research not only advances the frontiers of biosensor technology but also exemplifies how engineering ingenuity can meet real-world health challenges head-on. By embedding sophisticated sensing capabilities into a commonplace object, Sonkusale and his team have charted a path toward revolutionizing how we perceive and measure the invisible burden of stress — transforming a mundane daily ritual into a powerful health assessment tool.
Subject of Research: Biosensor technology for real-time stress monitoring using saliva-sensing dental floss
Article Title: Saliva-Sensing Dental Floss: An Innovative Tool for Assessing Stress via On-Demand Salivary Cortisol Measurement with Molecularly Imprinted Polymer and Thread Microfluidics Integration
News Publication Date: 17-Apr-2025
Web References:
- ACS Applied Materials and Interfaces Article
- Tufts University Research News on Stress and Cognitive States
References:
Sonkusale, S. et al. Saliva-Sensing Dental Floss: An Innovative Tool for Assessing Stress via On-Demand Salivary Cortisol Measurement with Molecularly Imprinted Polymer and Thread Microfluidics Integration. ACS Applied Materials & Interfaces (2025). DOI: 10.1021/acsami.5c02988
Image Credits: Nafize Ishtiaque Hossain
Keywords: Stress responses, Sensors, Dental care, Cortisol
