Stretchable and conformable electronic circuits are becoming one of the prominent building blocks of emerging consumer and industrial devices. By leveraging the low-strain high-deformation and conformability characteristics of serpentine interconnects, such devices are enabling novel sensing, energy harvesting, and healthcare applications. Of particular interest in this study are micro-fabricated island-bridge layout devices that are commonly employed in large-area sensing applications. Such stretchable devices consist of multiple node “islands” connected by highly-expandable serpentine pattern interconnect “bridges”. To date, these devices have been built for small amounts of and/or uniform stretching of the bridges, neither of which required careful consideration on the relative stretching behavior of interconnects. In this study, we propose a novel technique for designing highly-stretchable electronic devices with islands positioned at pre-identified objective locations, such as stress concentration regions in a structural health monitoring application. 

Our design approach is based on a multi-scale modeling scheme. In meso-scale, we simulate stretching of various serpentine patterns and create an accurate approximation that parametrizes the relationship between the design variables and serpentine stretching characteristics. By incorporating this information to macro-scale, where interconnect responses are described by this parametrization, we come up with a surrogate model of the full device. Via this model, a broad range of interconnect configurations are iteratively simulated with a high accuracy, at a very low computational cost to determine a set of suitable interconnect parameters that yields the target configuration. Our discussion also includes the steps we have taken to design the search algorithm to find such parameters, and the optimization approach we have employed for generating micro-fabrication scale device design from the obtained parameters. As a demonstrator of the technique, we design and fabricate a highly non-uniform stretchable device consisting of 63 nodes positioned to create the letter “S”. The quantitative results, which compare the pre-defined target, computationally simulated, and experimentally achieved node positions, demonstrate the remarkable design capability of our technique.


Target Specific Design of Large Area Stretchable Electronics

Division / Sponsors: 
Aerospace Division

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2020/volume/84027

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