Determination of mechanical properties and actuation behaviors of polypyrrole-copper bimorph nanoactuators

This paper reports on a polypyrrole (ppy) based bimorph nanoactuator. The nanoactuator consists of ppy nanowire and Cu thin film. To create a nanoactuator, a (10±5)-nm-thick Cu film was precisely deposited on one side of a (13.7±1.0)-μm-long and 270±20 nm diameter ppy nanowire. The bimorph was thermally actuated using the mismatch of the coefficients of thermal expansion (CTEs) between Cu and ppy. The CTE of ppy nanowire was obtained by measuring the deflection of the bimorph. The measured CTE of ppy was (12±1×10^-6)/K, which was found to be much less than CTE of a typical polymer. Further, the amount of the force generated by the ppy/Cu bimorph was measured by lateral force microscopy (LFM). The measured force from the nanoactuator was approximately 1 nN at δT=100 K.