2.5/3D dynamically stretchable and permanently shaped electronic circuits

Conventional electronic circuits are made up of electronic components assembled on either rigid substrates like FR4 and ceramic or on flexible substrates based on polymers such as polyimide, PET and PEN foils. The latter type of substrates offers considerable improvements in freedom of motion over its rigid complement although the deformations are still pretty limited due to the inability of common electronic materials, such as metals, to cope with the corresponding deformation. Moreover, the assembly of rigid electronic components can often reduce the circuit's ability to bend. The current trend towards increased component density on substrates makes the final assembly even less flexible. However, electronic circuits which can fully conform and easily fit in the arbitrary curved surface topologies are of keen interest in various areas of applications. Aside from flexibility, a certain degree of stretching is required for the three-dimensional shaping of electronic systems. Hence, deformability will offer electronics a number of additional features like bendability, conformability shaping and lightweight. Three-dimensional shaped electronics can be obtained either by multi-time (dynamic or elastic) or one time (static, permanent) stretching. In this paper an introduction on deformable and conformable electronics is outlined highlighting the different existing approaches. Some examples of flexible and stretchable electronic applications will be provided in various fields.