Nonlinear electromechanical topology optimization method for stretchable electronic interconnect structures

The conductive interconnect structure that connects the electrical functional devices is an important micro-nano structure in stretchable electronics. Given the reliance of numerous devices on steady electrical currents for operation, stretchable electronics would benefit from interconnects with minimal resistance variation during deformation. This paper proposes a topology optimization method for the design of stretchable interconnect structures with stable resistance under large deformation. In the proposed method, an equal material method considering geometrically nonlinear and electromechanical coupling effects is developed to evaluate the resistance of a deformed structure. Besides, a new connectivity control method is proposed to ensure the connectivity between the inlet and outlet by making full use of the electrical problem itself. To achieve the design goal of connected interconnect structures with negligible resistance fluctuation during stretching, a topology optimization formulation is established, and the corresponding sensitivity is also analytically derived. Several numerical examples show that the proposed method is capable of computationally and intelligently generating stretchable structures with extremely small variations in resistance during stretching.