The oxidation of thin, uniform and electrochromic films of polypyrrole, polyaniline and poly(methylaniline), after polarization at high cathodic potentials, takes place by formation and growth of nuclei of oxidized dark material on the reduced clear material. Digital pictures followed the evolution of the nuclei. When the growth of the nuclei was interrupted by switching off the polarization, the system was not stable and the reduced regions partially oxidizes at expenses of the oxidized ones that partially reduces, whatever the intermediate growth of the nuclei. Any final uniform intermediate composition of the counterion can be attained: the oxidized polymer is a non-stoichiometric material. The electro-chemo-mechanical (volume change) property of the conducting polymers is based on the change of the material composition. The subsequent devices, as artificial muscles, show uniform and reverse movments. The muscles act simultaneously as sensors and as actuators, sensing the magnitude of a weight adhered of hanged at the bottom of the muscle. When the muscle moves free droved by a constant current, and touches an obstacle, the working potential increases: this is a touching sense. The potential gradient and the extra-consumed energy are proportional to the slided weight: this is a tactile sense. (C) 2004 Elsevier Ltd. All rights reserved.