A footwear including a body; a base structure; and one or more electrical energy generators disposed in the base structure for generating electrical energy upon application of an impact to the base structure. The footwear is used to produce electrical energy by impacting a base structure of the footwear;...http://www.google.de/patents/US8087186?utm_source=gb-gplus-sharePatent US8087186 - Piezoelectric-based toe-heaters for frostbite protection
