Deformability analysis and improvement in stretchable electronics systems through finite element analysis

Stretchable electronic systems employ a combination of extremely deformable substrates with electrically conductive inks printed on their surface, on which components are connected. The absence of solid metal as conductive material greatly enhances the deformability of these systems. However, although being able to sustain high deformation, the presence of rigid components heavily affects the achievable deformation levels due to strain concentrations near the interconnection area. In order to improve stretchability under these conditions, a combination of research on materials for conductive inks and optimization of the employed layout is needed. Especially for the latter, the use of Finite Element (FE) modeling is very useful, since it allows to locate critical regions for deformation behavior and to perform design optimization and instability analyses. In this work, the authors show the application of this strategy to improve mechano-electrical performance of the system under uniaxial tension by modelling and then modifying the overall stiffness of specific sample regions. Depending on the specific need, different strategies can be adopted to intervene on stiffness changes, such as material addition to specific regions. This work shows that, in particular, a simple technique such as laser cutting can be used to tailor the local material parameters at a deeper level, thus allowing decrease in stiffness gradients and a general enhancement of electrical performances under high levels of uniaxial deformation of the sample, as also predicted in the FE analyses.