A new device could soon change how people track their stress\u2014and all it takes is flossing your teeth.<\/p>\n
Developed by researchers at Tufts University<\/a>, this innovative dental floss does more than clean your mouth. It collects your saliva and measures cortisol, a hormone linked to stress, in real time. The system blends a thread-based microfluidic sensor with cutting-edge materials that can detect minute levels of cortisol quickly and accurately.<\/p>\n A New Way to Track Stress<\/p>\n Stress is a natural response to life\u2019s challenges. Short-term stress can help you stay focused. But long-term stress is linked to health problems like high blood pressure, anxiety, depression, and heart disease. Detecting and managing chronic stress is vital to staying healthy.<\/p>\n This dental floss pick has a sensor that can assess your stress level. (CREDIT: Atul Sharma and Nafize Ishtiaque Hossain) <\/p>\n Yet, the tools we use to measure stress haven\u2019t kept up. Right now, people often rely on questionnaires or psychiatric evaluations, which are subjective and don\u2019t give instant feedback. Blood tests<\/a> can track stress hormones, but they\u2019re not convenient for daily use. They need lab visits and equipment most people don\u2019t have access to.<\/p>\n That\u2019s why a team led by Sameer Sonkusale, a professor of electrical and computer engineering at Tufts, wanted a stress monitor that fit seamlessly into everyday life.<\/p>\n \u201cIt started in a collaboration with several departments across Tufts, examining how stress and other cognitive states affect problem solving and learning,\u201d said Sonkusale. \u201cWe didn\u2019t 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? Cortisol<\/a> is a stress marker found in saliva, so flossing seemed like a natural fit to take a daily sample.\u201d<\/p>\n Turning Dental Floss into a Lab<\/p>\n The flossing device looks like a typical plastic floss pick. But when you floss, the thread captures saliva and sends it through a narrow channel to a flexible sensor hidden in the handle. This microfluidic thread uses capillary action to move saliva to a detection area. There, embedded electrodes analyze cortisol levels on the spot.<\/p>\n The secret lies in how the sensor detects cortisol. The team used a method called electropolymerized molecularly imprinted polymers\u2014or eMIPs. These are synthetic materials<\/a> that can \u201cremember\u201d and capture specific molecules.<\/p>\n Think of it like making a mold of a key. A polymer is formed around a cortisol molecule, then the molecule is removed, leaving behind a perfect mold. When new cortisol molecules enter, they fit into the mold and trigger a response in the sensor.<\/p>\n (a) Role of cortisol in stress response; (b) Proposed saliva sensing dental floss use case with the embedded cort-eMIP sensor. The floss is connected to a portable potentiostat for readout and signal transmission to a mobile device. (CREDIT: ACS Applied Materials & Interfaces) <\/p>\n This internal detection system doesn\u2019t need extra chemicals or sample prep, unlike older tests. It\u2019s faster, cleaner, and easier to use.<\/p>\n The sensor can spot cortisol levels as low as 0.048 picograms per milliliter. That\u2019s nearly 100,000 times lower than the typical cortisol level in saliva<\/a> during stress. And it only takes about 12 minutes to get a result.<\/p>\n Proven Accuracy, Real-World Promise<\/p>\n Tests using both artificial and human saliva showed the floss sensor\u2019s accuracy nearly matches that of standard lab tests like ELISA. Results had a 98.64\u2013102.4% recovery rate with only 5% variation. The readings also matched closely with traditional methods, showing a correlation of 0.9910\u2014a near-perfect match.<\/p>\n Demonstration of sampling (saliva, 0.10 mL) and flow of saliva from flossing site to waste zone using sulforhodamine B (SRB, a dye) for visual confirmation. (CREDIT: ACS Applied Materials & Interfaces) <\/p>\n The platform\u2019s sensor is made using a special laser-engraved graphene material<\/a>, which offers high surface area and excellent electrical properties. This boosts sensitivity and ensures precise detection, even in complex saliva samples.<\/p>\n The floss contains four working parts: the saliva collection thread, a capillary microfluidic channel, a flexible electrochemical sensor, and a waste zone. The sensor uses a polypyrrole-prussian blue matrix that generates an electrical signal when cortisol binds to its memory sites. This signal is sent wirelessly to a mobile device for easy tracking.<\/p>\n Unlike bulkier stress sensors like mouthguards, this floss-based version doesn\u2019t feel intrusive. Because it\u2019s used as part of a normal hygiene routine, it encourages consistent use without raising anxiety or requiring extra effort. That\u2019s important because even the act of measuring stress can trigger stress<\/a>, skewing the results.<\/p>\n Beyond Stress: A Platform for Other Conditions<\/p>\n The dental floss sensor doesn\u2019t just stop at cortisol. Because eMIP technology is versatile, researchers can quickly design sensors for other salivary biomarkers. That includes estrogen for fertility tracking, glucose for diabetes, or markers for early cancer detection. There\u2019s even potential to track multiple biomarkers at once for a fuller picture of your health.<\/p>\n (a) FTIR spectrum of PLEG electrode (black curve), cort-eNIP\/PPy\/PB\/PLEG electrode (blue curve), cort-eMIP\/PPy\/PB\/PLEG electrode (green curve) recorded at a scan rate of 32 cm\u20131 in ATR mode; SEM micrograph of (b) PLEG electrode; (c) cort-eMIP\/PPy\/PB\/PLEG electrode; (d) cort-eNIP\/PPy\/PB\/PLEG electrode. (CREDIT: ACS Applied Materials & Interfaces) <\/p>\n \u201cThe eMIP approach is a game changer,\u201d said Sonkusale. \u201cBiosensors have typically been developed using antibodies or other receptors that pick up the molecule of interest. Once a marker is found, a lot of work has to go into bioengineering the receiving molecule attached to the sensor. eMIP does not rely on a lot of investment in making antibodies or receptors. 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.\u201d<\/p>\n Sonkusale believes the biggest value of this new floss isn\u2019t in diagnosis, but in regular monitoring. For now, blood is still the gold standard<\/a> for diagnosing medical conditions. But saliva testing is a great way to keep tabs on how treatments are working, or to flag early signs of trouble.<\/p>\n \u201cFor diagnostics, blood is still the gold standard,\u201d he explained, \u201cbut once you are diagnosed and put on medication, if you need to track, say, a cardiovascular condition over time to see if your heart health is improving, then monitoring with the sensor can be easy and allows for timely interventions when needed.\u201d<\/p>\n (a) Process flow of human saliva collection and corresponding screening methods; quantification of salivary cortisol using ELISA and saliva sensing dental floss in (b) in control (c) in stress-induced student volunteer; (d) establish a correlation between ELISA and saliva sensing dental floss for salivary cortisol quantification (Note: Each data point is an average of triplicate measurement (n = 3)). (CREDIT: ACS Applied Materials & Interfaces) Toward Smarter, Easier Healthcare<\/p>\n