Graphene-Enabled Wearable for Remote ECG and Body Temperature Monitoring

This article presents a comprehensive study on the synthesis, characterization, and integration of laser-synthetized graphene-based materials in a wearable device for noninvasive physiological monitoring. Laser-induced graphene (LIG) and laser-reduced graphene oxide (LrGO) materials are synthesized and characterized under different techniques to analyze and compare their structural and chemical properties, including scanning electron microscopy (SEM), micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). These materials are used afterward for the fabrication of temperature sensors, micro-supercapacitors (MSCs), and electrocardiogram (ECG) electrodes. In particular, the temperature dependence of the electrical conductivity of LrGO is exploited for the fabrication of temperature-dependent resistors with a sensitivity of −1.23 k $\Omega \cdot ^{\circ }$ C1, which are used as body temperature sensors after being encapsulated into polydimethylsiloxane (PDMS) to increase their linearity and immunity to humidity changes. Moreover, both MSCs and ECG electrodes are developed by leveraging the highly porous structure of LIG, demonstrating a good electrochemical and ECG acquisition performance. Furthermore, a wearable device is designed and fabricated integrating these graphene-based components in a rigid-flex printed circuit board (PCB) together with a Bluetooth low energy (BLE) microcontroller, thus enabling the wireless transmission of the physiological data to external monitoring devices. The power consumption has been optimized for extended battery life, allowing continuous monitoring over prolonged periods. Overall, this study demonstrates the feasibility and effectiveness of integrating graphene-based materials into real wearable applications.