VOC Biomarker Monitoring for Diabetes Through Exhaled Breath Using Ag/P-TiO2 Composite Plasmonic Sensor

The detection of diabetes at an early stage is considered to be highly significant in the successful treatment of the disease. The patient has been reported to generate unique volatile organic compounds (VOCs) profiles in their exhaled breath which can be utilized as biomarkers to diagnosis the disease conditions. In this article, we theoretically report a simple breath sensor for the highly sensitive detection of isopropanol (IPA), which is the biomarker for both types of diabetes, in exhaled breath using a D-shaped composite plasmonic sensor (DSCPS). The sensing response of the sensor is characterized by using a full-vectorial finite element method (FEM) for the detailed analysis of DSCPS, where a porous TiO ₂ (P-TiO ₂ ) layer is used as low index sensing material on the top of thin Ag film. The design of the proposed sensor is based on the wavelength modulation technique. A maximum sensitivity of 0.25, 0.35, 0.45, and 1.35 nm/% can be achieved for 20%, 40%, 60%, and 80% volume fraction of IPA, respectively, with a 30% porosity of TiO ₂ , which is the maximum filled porous voids that provides the highest sensitivity.