A Review of CMOS-Compatible Flexible Biosensors Based on Polymer Electronics for Wearable Healthcare

Flexible wearable biosensors have emerged as a promising technology for continuous, noninvasive health monitoring, driven by the growing demand for personalized healthcare and an aging global population. Polymeric substrates such as polyethylene terephthalate (PET), polyimide (PI), and polydimethylsiloxane (PDMS) provide lightweight, flexible, and low-cost platforms that conform to the human body, but their practical deployment requires reliable integration with complementary metal–oxide–semiconductor (CMOS) electronics for signal acquisition, processing, and wireless communication. This review summarizes recent advances in CMOS-compatible flexible biosensors, emphasizing polymer-based sensing platforms, circuit-level integration, and system-on-chip (SoC) architectures for wearable healthcare applications. Flexible sensing mechanisms, including electrochemical, capacitive, resistive, and transistor-based devices, are discussed alongside CMOS analog front-end circuits, low-noise amplifiers, analog-to-digital converters, and ultra-low-power signal conditioning techniques. Finally, key challenges in CMOS–flexible sensor integration, including mechanical reliability, biocompatibility, signal integrity, packaging, and scalable manufacturing, are discussed, together with future directions toward highly integrated, intelligent, and energy-efficient wearable healthcare systems.