**2.1 Introduction**

PPy actuators have been regarded as a possible candidate for an artificial muscle because the generation of stress is nearly ten times larger than human muscles. However, the expansion and contraction ratio of a PPy actuator was only 1–3 % which was far smaller than the value of human muscle, 25% (Hara et al., 2005, Baughman, 1996). However, Hara et. al. recently reported that an expansion and contraction ratio of their PPy actuators exceeded 40%, which is very encouraging (Hara et al., 2004). There are also several reports to improve the expansion and contraction ratios by modifying PPy film deposition conditions such as temperatures and modifying supporting electrolyte solutions (Hara et al., 2005a, 2005b, 2005c, Zama et al., 2005a, 2005b, Ogasawara et al., 1986).

In this section, a new structure of PPy actuators to improve the expansion and contraction ratio is proposed. Here, the details of fabrication procedures and the characterization results of the corrugated PPy soft actuator are reported.
