Design and Fabrication of Large-Area, Redundant, Stretchable Interconnect Meshes Using Excimer Laser Photoablation and In Situ Masking

Stretchable interconnects play an important role towards the realization of the realm of systems that include large-area sensor skins and wearable electronics. These interconnects must be reliable and robust for viability, and must be flexible, stretchable, and conformable to nonplanar surfaces for diverse applicability. This research describes the design, modeling, fabrication, and testing of stretchable interconnects on polymer substrates using metal patterns both as functional interconnect layers and as
in situ
masks for excimer laser photoablation. The fluences for photoablation of polymers are generally much lower than the threshold fluence for removal or damage of metals; thus, metal thin films that are designed as structural layers in the sensor skin can be used as
in situ
masks for polymers if the proper fluence is used. Self-aligned single-layer and multilayer interconnects of various designs (rectilinear and “meandering”) have been fabricated, and certain “meandering” interconnect designs can be stretched up to 50% uniaxially while maintaining good electrical conductivity and structural integrity. Furthermore, redundant interconnect meshes have been modeled and fabricated that increase the viability of the interconnect mesh while stretching up to 30% uniaxially and a prototype redundant interconnect mesh has been fabricated using seamless-scanning large-area fabrication techniques.