Yihan Liu, a doctoral student in the Department of Applied Physical Sciences at the University of North Carolina, is addressing significant challenges in wearable health sensors through innovative research. His work focuses on wearable optical sensing, which uses light to monitor physiological conditions beneath the skin. Current optical wearables face limitations such as shallow light penetration and motion artifacts that distort signals. Liu's dissertation, titled “Intelligent Wearable Optical Sensing: Multimodal, Multichannel, and Multi-Wavelength Approaches for Advanced Physiological Monitoring,” proposes solutions to these issues. By integrating optical sensors with inertial measurement units (IMUs), Liu's team developed a system that effectively synchronizes data from different types of sensors, allowing for clearer physiological readings even amid motion. Additionally, Liu introduced biocompatible microneedle waveguides to enhance light penetration, enabling more accurate measurements of blood oxygen levels. His research also includes a high-resolution optical myography array that maps muscle activity, demonstrating the potential to interpret complex gestures and assess athletic performance. Furthermore, Liu's team developed a multi-wavelength spectroscopic sensor that can continuously measure ethanol levels in the blood without invasive procedures. These advancements signify a leap towards more reliable and effective wearable health monitoring devices, paving the way for personalized diagnostics and improved human-machine interaction.