This book defines and elucidates the topic of smart "second skin" clothing, which must be flexible, washable, ironable, long-lasting and battery-free. We explore the possibilities for its use in fields such as health, well-being, sports and leisure. Smart Patches presents techniques that can be used within the limits established by regulations (EMC, normative, GDPR, ANSES, etc.) to help make smart clothing a marketable product at an affordable price. This book studies the creation and performance of various sensors and biosensors based on graphene materials and describes the functioning of Intra-Body Communications (IBC), as well as all the internal and external parameters involved in this type of technology. The performances and limits of these IBC and technologies are presented, together with concrete application examples.