Research Progress on Hydrogel-Based Multifunctional Sensors for Health Monitoring

Abstract

Hydrogel-based sensors (HBS), as core devices at the intersection of flexible electronics and biomedical engineering, exhibit great application potential in areas such as human motion detection and health monitoring due to their excellent mechanical properties, conductivity, high sensitivity, and biocompatibility. This paper first explains the research progress of HBS, focusing on the intrinsic relationships among material design, structural optimization, performance regulation, and application scenarios. It then examines the sensing mechanisms, advantages, disadvantages, and application fields of four types of sensors: resistive, capacitive, piezoelectric, and triboelectric, with a focus on their materials and structures. By introducing polymer materials such as polyacrylamide (PAM), poly (2-acrylamide-2-methylpropanesulfonic acid) (PAMPS), and polyvinyl alcohol (PVA); polysaccharide materials like alginate, cellulose, and chitosan (CS); as well as conductive fillers such as MXene, carbon nanotubes, polypyrrole (PPy), and polyaniline (PANI), strategies for regulating electron and ion migration behaviors have been implemented. Through the construction of double-network (DN) or interpenetrating polymer network (IPN) structures, HBS with excellent mechanical properties, conductivity, anti-swelling performance, transparency, and biocompatibility have been developed. These sensors have been successfully applied in wearable and implantable scenarios, including human motion detection (e.g., pulse monitoring, joint motion tracking, facial expression recognition) and health monitoring (e.g., powering cardiac pacemakers, sweat analysis). Starting from the diverse sensing mechanisms of HBS, this paper provides a detailed summary of the construction principles, diversified material regulation, motion mode detection, and implantable sensing applications of HBS-based bioelectrical medical monitoring systems. Finally, the development prospects of HBS-based bioelectrical medical monitoring systems are discussed.