This thesis provides reliable methods and building blocks in order to realize smart SiF by combining Si- with foil-based components on flexible substrates. Building blocks such as 2-D and 3-D electrical interconnections, hybrid integration techniques and especially modeling procedures (i.e. flexural mechanics and CZM) to optimize multi-layer systems are here described and their insights discussed. These methods can be employed to develop not only RFID smart labels but many other types of flexible smart systems capable of interacting with their environment.