An Overview on Hydrogel-based Motion Sensors

On the other hand, according to the application fields of motion sensors and their frequent use, the need for hydrogel with desirable mechanical properties such as remarkable toughness, self-healing property after damage and dynamic stability is felt. Therefore, in this article, the recent advances for the preparation of hydrogel with high electrical conductivity, sensitivity to considerable strain, and desirable mechanical properties suitable for motion sensor design are reviewed. In the recent decade, flexible electronics have gained considerable attention due to their widespread use in various fields. In the meantime, there has been a growing demand for wearable strain sensors, which are applicable in human motion monitoring, robotics, touch panels, and so on. In this respect, integrating polymers with electrical conductive agents are the most common strategy to develop flexible electronics. Among polymers, the intrinsic electrical properties, appropriate mechanical properties, and biocompatibility of hydrogels made them a suitable candidates to serve as a strain sensor. However, it is essential to increase hydrogels electrical properties by using ions and electrical conductors to attain high strain sensitivity.On the other hand, the frequent use of hydrogels for human motion monitoring needs suitable mechanical properties such as sufficient toughness, dynamic durability, and high stretchability. To endow hydrogels with these features, some strategies such as nanocomposite hydrogel, double network, and inducing abundant reversible bonds within the hydrogels have been employed. Therefore, in this article, the latest achievements regarding the development of hydrogel-based strain sensors for human motion monitoring and the recent approaches leading to considerable electrical properties, high strain sensitivity, and suitable mechanical performance are reviewed.