[1] Hanyang Univ, Dept Biomed Engn, Ctr Selfpowered Actuat, Seoul 04763, South Korea
[2] Sungkyunkwan Univ, Samsung Biomed Res Inst, Dept Physiol, Sch Med, Suwon 16419, South Korea
[3] Univ Texas Dallas, Alan G MacDiarmid NanoTech Inst, Richardson, TX 75083 USA