Emerging Trends in System-Integrated Wearable Epidermal and Flexible Electrodes: Material Design and Applications in Physiological Monitoring

Electrophysiological (EP) disorders are serious and life-threatening conditions but their prevention can be improved with advanced on-skin and implantable biomedical sensors. These sensors are expected to shift rapidly from the development stage to the commercial stage, offering next generation and more sustainable life-saving approaches. They have the potential to advance medical diagnostics and healthcare. However, current bioelectronic sensors face major challenges related to their biocompatibility, long-term monitoring, reliability, low signal-to-noise ratio (SNR), stability, and wireless data transmission. Addressing these issues requires a multidisciplinary approach that integrates bioengineering, neuroengineering, and data science. This review article covers the most recent developments in materials and methods for on-skin, flexible, and implantable biomedical sensors designed for biosignal monitoring. Advanced bioelectronics, such as electronic skin (e-skin), patches, electronic tattoos, headbands, smart textiles, and microneedles for biopotential monitoring are discussed. The review also identifies the key gaps in the current technologies and strategies to address these gaps. Future research directions for sustainable life-saving applications are proposed. Furthermore, the practical use of bioelectric signal-based human-machine interfaces (HMIs) for controlling devices such as home appliances and robots is also discussed, showcasing the potential of these technologies to enhance everyday life. This review inspires researchers to explore innovative solutions advancing the field toward next-generation sustainable life-saving applications.