Feasibility Study of Polarimetric 'Sweat-Sensing' of GlucosedissertationsMin, SeokkeecreatorToussaint, KimaniReaderXu, JimmyAdvisorMathiowitz, EdithReaderBrown University. Biology and Medicine: Biomedical Engineeringsponsor2024, 47 p.born digitalThesis (Sc. M.)--Brown University, 2024thesesBlood sugar is an important biomarker in the diagnosis and management of diabetes mellitus. Current sensing methods are invasive, painful, intermittent, and require complex chemical enzyme interactions. An alternative minimally invasive optical sensing method is studied in this work to assess its feasibility and potential. A sub-mm thick optical transmission microfluidic chip utilizing a ferromagnetic core/dielectric shell microfiber array grating was developed for the proof-of-concept polarimetric sensing of an optically active solution (sucrose, as a stand-in for glucose). The tested concentration range was from 0.01 mg/mL to 100.0 mg/mL, which includes the concentration range found in human sweat for glucose in literature. The 50-µm spacing microfiber array microfluidic chip was found to magnify the optical rotation by the sucrose analyte solution by several orders of magnitude within the tested range, over a broad spectral band of a linearly polarized light source with the electrical field oriented orthogonal to the microfibers. The calibration curve of the optical rotation was 0.1428 and 0.1225 degrees per logarithmic concentration (mg/mL) for wavelengths of 1000 and 1200 nm, respectively. Due to the flexibility and scalability of the microfiber and their arrays, the wicking effect of the array and its capability for iontophoresis for sweat generation and extraction, as well as measurement range that covers the concentrations found in sweat, the platform has the potential for enabling many applications, one of which is a wearable sweat sensor of glucose.DiabetesOpticsBiosensingSucrosePolarimetryEnglishRPB20240502