Smart watch technology frontier-Blood Glucose Monitoring
For the first time, we have successfully demonstrated a fully integrated and self-powered wearable system in a smartwatch fashion for continuous monitoring of sweat glucose levels. Without external charging facilities, the smartwatch can be self-powered with flexible photovoltaic cells for energy harvesting/conversion and flexible Zn-MnO2 batteries as energy storage devices. Such photocharging batteries performed a stable self-powered capability with a high energy storage capacity to support the continuous functionality of the system. The glucose sensors delivered desirable sensitivity and selectivity for sweat glucose monitoring and the integrated PCB and E-ink screen enables real-time and in situ data analysis/display, which eliminates transmission units and external reading devices. Such fully integrated systems provide operational convenience and safety, as well as device miniaturization, which are highly desirable for wearable and portable applications. Notably, the reliability of such a self-powered smartwatch for real-time glucose level monitoring was verified. Real-time and continuous on-body evaluation on sweat glucose level with the as-fabricated smartwatch was successfully conducted during both equilibrium status and dynamic activities. The as-developed fully integrated and self-powered smartwatch is highly desirable in daily health monitoring and fitness management, and provides a promising protocol for statistical studies to reveal correlations between sweat compositions and human body dynamics.