A comprehensive review of wearable devices for non-invasive biosensing

Wearable biosensors have emerged as powerful tools for non-invasive, continuous health monitoring, enabling the real-time analysis of physiological and biochemical markers in body fluids such as sweat, saliva, tears, and exhaled breath. This review provides a comprehensive overview of the advancements in wearable biosensing platforms over the past five years, with a particular focus on device-level innovations, diverse sensing modalities, clinical applications, commercialization efforts, and future prospects including AI integration. The key technologies discussed include electrochemical and optical sensors embedded in patches, mouthguards, contact lenses, and smart masks, all of which are tailored to specific biofluids and diagnostic needs. The review highlights innovations in antifouling coatings, self-healing materials, and microfluidic control systems that improve device durability and accuracy under dynamic physiological conditions. The review also provides a critical analysis of the key challenges, including biofluid variability, environmental interference, and power supply limitations. It further explores potential directions for future research, such as the transition from laboratory prototypes to commercial products, the integration of edge AI computing, and the development of standardized data workflows. Importantly, it also highlights regulatory hurdles and the need for standardization to facilitate clinical translation and ensure interoperability. The considered applications range from glucose, lactate, cortisol, and electrolyte testing to monitoring infectious pathogens and vital signs. Challenges such as biofluid variability, environmental interference, and sensor biocompatibility are critically reviewed. The review also explores the transition of wearable devices from laboratory prototypes to commercial products, discussing current market offerings and regulatory considerations. Looking ahead, the integration of multifunctional sensor arrays and AI-driven data analytics will revolutionize health diagnostics, paving the way for the development of smart, user-adaptive, and clinically reliable wearable biosensing platforms for revolutionizing personal health monitoring and disease monitoring.