Enabling Sweat-Based Biosensors: Solving the Problem of Low
Enabling sweat-based biosensors: Solving the problem of low biomarker concentration in sweat A dissertation submitted to the Graduate School of the University of Cincinnati in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biomedical Engineering of the College of Engineering & Applied Science by Andrew J. Jajack B.S., Biology, Wittenberg University, 2014 Committee Chairs: Jason C. Heikenfeld, Ph.D. and Chia-Ying Lin, Ph.D. Abstract Non-invasive, sweat biosensing will enable the development of an entirely new class of wearable devices capable of assessing health on a minute-to-minute basis. Every aspect of healthcare stands to benefit: prevention (activity tracking, stress-level monitoring, over-exertion alerting, dehydration warning), diagnosis (early-detection, new diagnostic techniques), and management (glucose tracking, drug-dose monitoring). Currently, blood is the gold standard for measuring the level of most biomarkers in the body. Unlike blood, sweat can be measured outside of the body with little inconvenience. While some biomarkers are produced in the sweat gland itself, most are produced elsewhere and must diffuse into sweat. These biomarkers come directly from blood or interstitial fluid which surrounds the sweat gland. However, a two-cell thick epithelium acts as barrier and dilutes most biomarkers in sweat. As a result, many biomarkers that would be useful to monitor are diluted in sweat to concentrations below what can be detected by current biosensors. This is a core challenge that must be overcome before the advantages of sweat biosensing can be fully realized. The objective of this dissertation is to develop methods of concentrating biomarkers in sweat to bring them into range of available biosensors.
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