Current-generating double layer shoe with a porous sole
  We present a principle and a simple theory of a novel reverse electroactuator, in which the electrical current is generated by pumping of an electrolytic liquid into nonwetting pores of a polarized electrode. The theory establishes the relationship between the variation of external pressure and the electrical current. The effective current density is amplified by high porosity of the electrode. The suggested principle can be implemented into a design of a shoe which will be generating an AC current simply by walking. Estimates of typical parameters and operation regimes of such device suggest that one can easily generate a peak current density of ~17 mA/cm2. This would produce some 1.7 A from each shoe at 0.65 W average power density, without hampering walking. 
Anatoly B. Kolomeisky and Alexei A. Kornyshev
cond-mat.soft cond-mat.mes-hall