Proceedings Article | 2 March 2022
KEYWORDS: Sensors, Fiber optics sensors, Microfluidics, Electrodes, Skin, Coating, Graphene, Proteins, Multiplexing, Calibration, Carbon nanotubes
This paper presents a novel, lightweight, integrated, and wearable sensor for real-time and multiplexed monitoring of biomarkers in sweat. We report a wearable skin patch made with a benchtop craft cutter, thereby resulting in low-cost, roll-to-roll, and cleanroom-free fabrication. The integrated device is wearable on the arm like a small flexible bandage that is comprised of a microfluidic channel and a dual-modality transducer. The microfluidic channel ensures fast, continuous, and reproducible sweat transport from the skin to the sensors while minimizing the evaporation and contamination of sweat droplets. The transducer generates both electrochemical and fiber-optic based localized surface plasmon resonance (LSPR) signals on a single chip. Furthermore, sweat collection is noninvasive compared to other body fluids (e.g., blood, urine, or saliva), correlates well with blood biomarker levels, and bypasses diurnal rhythm challenges. Elevated levels of cytokines, including interleukin-6 (IL-6), predict chronic diseases including diabetes, heart disease, and therapeutic responses in fatigue, pain, and depression. The electrochemical sensor measures the IL-6 levels with a high sensitivity of 122.59 μA (pg/mL) -1 cm-2 and a limit of detection (LoD) of 0.886 fg/mL. The fiber-optic sensor exhibits LSPR shifts in response to varying IL-6 levels with a sensitivity of 0.87 % Log(ng/ml)-1 and LoD of 1.48 ng/ml. Our integrated sensor has the potential to overcome the challenges associated with the current infection/inflammation screening technology by detecting a low concentration of inflammatory biomarkers in sweat that is rich in physiological and metabolic information, providing multiplexed monitoring on a single chip, and utilizing a simple screen-printing technique for large-scale fabrication. This integrated sensor holds the potential to provide real-time feedback on the infection progression and allow on-demand drug delivery.
