Optimization of compound serpentine–spiral structure for ultra-stretchable electronics

Stretchable electronics is a rising technology, promising to replace the conventional, brittle and rigid electronics for applications that demand mechanical compliance to irregular, complex and mobile shapes. Several approaches have been proposed to find an optimum balance between electrical and mechanical characteristics. These include finding new flexible electronic materials, integrating both organic and inorganic materials or incorporating structural modifications to conventional materials, thus achieving flexibility and stretchability. Previously, the use of spiral-based structures made entirely out of silicon, a well-mature and high-performing material, has been proposed as a platform for ultra-stretchable electronic applications. In this paper we have demonstrated the use of spiral-based compound, fractal-inspired structures to optimize and greatly reduce the stress and strain distribution along them. The integration of double-arm spirals with variants of serpentine and horseshoe structures has been considered and their mechanical response to an applied deformation has been performed through finite element analysis (FEA). The proposed compound structures provide outstanding stretching capabilities and demonstrate up to ∼55% reduction in stress/strain, as well as a more uniform distribution as compared to the original, un-optimized spiral-based structure. These results show the remarkable potential of combining structures to optimize their mechanical behavior, thus accomplishing more robust platforms that will leverage the development of stretchable electronics.