Design of stretchable microwires for flexible networks

An investigation was performed to characterize the mechanical response of extendable, flexible polymer microwires for large area network applications. The increasing need to cover large areas with a high density of sensors and electronic devices for structural health monitoring requires the realization of sensor networks mounted onto flexible polymers which can be expanded to areas 104 % times higher than the original areas. This is achieved by building thousands of micronodes interconnected by extendable microwires at the microscale. The mechanical response of the extendable microwires is the key element to building networks that are robust enough to withstand fabrication, elongation and integration into materials or structures. A numerical and experimental study is presented here to describe the elongation process of a single microwire. A 3-D finite element model was used to optimize the microwire design, its extendibility and reliability by minimizing local stress/strain concentrations, avoiding in-plane and out-of plane plastic strains and controlling the maximum extension of the microwires.