Research progress onconductive hydrogels and their applications in flexible sensors: a review

Conductive hydrogels are a class of novel conductive materials characterized by a biomimetic structure, excellent conductivity, adjustable mechanical properties, and diverse functionalities and structures. Moreover, they possess the unique capability to convert external stimuli (such as pressure, strain, temperature, etc.) into electrical signals, making them highly promising in the field of smart wearables. This paper reviews the latest research progress on conductive hydrogels in flexible sensor applications, beginning with a discussion on the preparation methods and performance metrics of conductive hydrogels based on metal nanoparticles, carbon nanomaterials, MXenes, conductive polymers, and free ions. Subsequently, it explores the application prospects of conductive hydrogels in flexible sensors, emphasizing flexible strain sensors, temperature sensors, pressure sensors, and flexible electrodes. Finally, it discusses the future research directions for conductive hydrogels and the associated challenges.