Abstract— Over the last decades, we have seen an increased need for flexible hybrid electronics (FHE) especially in the mobile, wearable, and medical devices. Recently additional applications and technologies have emerged e.g. stretchable and conformable electronics. 3D and foldable smart devices enable novel applications with new levels of user convenience and human-machine interfaces.
The range of processes and materials applied in products and research has become very broad. Various types of flexible and stretchable base materials are available with different thermal, electrical and mechanical properties. They have to match the requirements of subsequent processes and those of the final application. Besides photolithographic processes novel flexible and stretchable electrical circuits are realized by different printing technologies using conductive polymers, percolation networks or liquid metals. Alternatively, higher densities can be achieved by photolithographic structuring of meander-shaped or buckling conductors or fine meshes. The modules can finally be dynamically flexible or stretchable or they can be brought in 3D shapes by 3D printing, thermoforming, or injection molding to generate smart 3D surfaces and structures.