Strain Sensor Applications of Mixed Ion Gels

초록

Mixed ion gels were employed to achieve strain sensors that monitored human motion. Ion gels are composed of ionic liquids and polymer networks. Ionic liquids are characterized by thermal and electrochemical stability at room temperature, and they impart ionic conductivity to ion gels. Mechanical properties of gels are primarily determined by the network type and architecture, and desired properties such as stretchability and durability can be attained via rational design of polymer precursors that form the scaffolds. The versatility of ion gels has enabled their implementations in various electronic and electrochemical applications. Wearable strain sensors are attached to human bodies and used to detect repetitive mechanical deformations associated with human motion. For this reason, it is necessary to control the mechanical and adhesion properties of the ion gels for sensor applications. We previously reported the phase behavior and mechanical properties of mixed ion gels. The phase separation dependence on the constituent composition of the ion gels was studied. This work expanded on the prior research and examined the mechanical, electrochemical, and adhesive properties of mixed ion gels. Mixed ion gels were prepared by blending two well-defined copolymers with ionic liquids. The strain sensors that detect human motion were fabricated based on the characterization results of the gel properties. The magnitude of the strains imposed on the devices was carefully controlled using a motorized stage, and a gauge factor was estimated based on the resulting change in the relative resistance. Long-term stability of sensor operation was also monitored.