A helical ionic polymer–metal composite actuator for radius control of biomedical active stents

Helical ionic polymer–metal composite (IPMC) actuators are newly developed to control the radius of biomedical active stents. The helix-shaped IPMC actuator is fabricated through the thermal treatment of an IPMC strip helically coiled on a glass rod. The helical IPMC actuator can be used to realize not only bending motion but also torsional and longitudinal motion. In particular, the dynamic responses of the helical IPMC actuators are evaluated according to various structural parameters such as diameter, pitch and width of the helical configuration. The present experimental results for the harmonic responses and frequency response functions show that diameter, among the structural parameters, plays an important role in the actuation performance required to efficiently control the radius of the helical stent. The static and dynamic responses of the helical IPMC actuators are also investigated with step and harmonic electrical inputs, a voltage–current diagram and a mechanical compression test. This study shows that a helical IPMC actuator can be used for biomedical smart systems capable of controlling the radius of active stents.