Advances of Carbon Nanotube Based Flexible Amplifiers for Skin-Mounted Physiological Signal Monitoring

Epidermal amplifiers, integral to noninvasive bio-signal monitoring that are in close proximity to the site of interest, have emerged as critical components in the evolution of wearable healthcare and diagnostics. Among various semiconducting materials, carbon nanotubes (CNTs) become one of the most promising candidates due to its great electronic properties. This review provides an overview of the recent developments in flexible amplifiers based on CNTs from the following aspects. The manufacturing strategies for CNT thin-film transistors (TFTs) are first discussed that preserve device integrity and performance from rigid to flexible platforms. The subsequent content concludes the recent development in CNT TFTs, including film deposition processes, high-k dielectric materials, and scaling behaviors, which are pivotal for enhancing the performance of flexible systems. The review further details various circuit topologies, from inverter-based to differential amplifiers, each offering unique advantages in gain, noise rejection, and bandwidth. Successful CNT-based amplifier implementations for physiological signal monitoring are highlighted, emphasizing their impact on wearable electronics. Finally, it discusses the challenges and future prospects of CNT-based flexible amplifiers, charting a course for the next generation of flexible electronics in personal health monitoring.