C. Vannucci
Tufts University,
United States
Keywords: Salivary sensor, hormone, electrochemical biosensing, at-home diasgnostics
Summary:
Hormones regulate essential physiological functions—from stress response and circadian rhythms to metabolism, mental health, and sleep. However, hormone fluctuations often go undetected because traditional diagnostics depend on infrequent, invasive blood draws and centralized laboratory analysis, which are costly and fail to capture subtle, time dependent changes. Rising rates of stress-related disorders, metabolic disease, mental health conditions, and hormone dysregulation—especially in women—underscore the need for accessible, continuous, and decentralized biomarker monitoring. Saliva provides a compelling alternative as a specimen matrix: it is painless to collect, clinically validated, and accurately reflects systemic hormone levels, including cortisol and other endocrine markers. Yet current salivary hormone tests still rely on laboratory processing or bulky point of care instruments, limiting their use outside clinical settings. To address these challenges, the SalivaSens platform (also called SensiFloss) was developed as a low cost, user friendly, at home hormone monitoring solution. The device integrates four components into a single dental floss–based system: an FDA approved flossing thread for sample collection, a capillary-driven thread microfluidic channel, a flexible cortisol sensor, and a waste reservoir for sustained unidirectional flow. During routine flossing, saliva is collected and passively transported to the sensing region without pumps or user intervention. The device architecture regulates saliva volume and flow, reducing variability due to viscosity, particulates, or user technique and ensuring consistent sample delivery. The cortisol sensor uses an electropolymerized molecularly imprinted polymer (eMIP) built on porous laser engraved graphene and a Prussian blue internal redox layer enables reagent free detection. The system detects cortisol down to ~10 pg/mL, across a broad 0.10–10,000 pg/mL range, with excellent linearity (R² = 0.9956). Results are delivered within 11–12 minutes. Validation studies demonstrated high accuracy (>98% recovery) and precision (5.01% RSD). The sensor maintained selectivity against structural analogs such as testosterone and corticosterone, as well as common salivary interferents. Human saliva measurements across stress stages confirmed sensitivity and reliability in real-world conditions. In a pilot study, the platform showed strong agreement with gold standard ELISA assays (r = 0.9910; error <5%) and stability for four weeks at 4°C with minimal performance drift. SalivaSens is designed for scalable manufacturing using standard dental and consumer health production methods such as extrusion, laser patterning, screen printing, and injection molding. By integrating sample collection, microfluidic transport, and reagent less sensing into a disposable floss based form factor, the platform supports routine, decentralized, at home monitoring of stress and endocrine function. Its modular design also allows expansion to additional salivary biomarkers, enabling broader applications in preventive health, chronic disease management, and digital health ecosystems.