(Invited) The New Paradigm in Passive Sweat Wearables: Temporal Profiling of Biomarkers to Elucidate the Relationship between Stress and Inflammation in Passively Expressed Eccrine Sweat

When the body is under stress, a lot of physiological processes work towards bringing the body back to its normal state. Cortisol, a stress hormone and TNF-alpha, a protein related to inflammation, are direct products of these physiological processes. The goal of this work is the demonstration of a biosensor that is capable of tracking these molecules in human sweat. The significance lies in simplifying chronic disease diagnostics, i.e. technique used to detect and monitor diseases in a non-invasive manner. This system is designed to be a wearable device that will track those physiologica process and use cortisol and TNF-alpha levels as indicators of user’s health status. Background: The HPA (Hypothalamic-Pituitary-Adrenal) axis is involved in maintaining homeostasis by engaging with the parasympathetic nervous system. During the process of chronic disease affliction to the body, this relationship is disturbed and there is an imbalance driven response observed with creation of disease related symptoms. This is of prime clinical importance when the body is chronically exposed to high levels of stress. By monitoring the two key components, cortisol, a direct product of the HPA axis and TNF-alpha, a pro-inflammatory cytokine, the manifestations of chronic stress on the homeostasis and diseased state of the body can be evaluated in a holistic/comprehensive manner. Materials and Methods: This work describes a novel sweat based sensing system which uses electrochemical modality to perform detection of cortisol and TNF-alpha. Results and Conclusion: This work highlights the development of an electrochemical detection system for the two biomarkers through human sweat. Limit of detection of the system is 1 ng/ml for cortisol and 1 pg/ml for TNF-alpha and dynamic range is 1-200ng/ml and 1-1000 pg/ml for cortisol and TNF-alpha respectively. This wearable system is designed to be a point of use, patient centric, chronic disease self-monitoring and management platform.