Biaxial Inflation Stretch Test for Printed Electronics

As flexible electronics technology matures, there is a growing need for the development of electromechanical reliability test methods for characterizing electronic materials under real-world loading conditions. To address this need, a new test method is proposed in which a flexible electronic sample is clamped around its periphery and subjected to an inflation pressure to induce a biaxial strain state. Inflation pressure and electrical resistance change are measured simultaneously, while strains are tracked in-situ using three-dimensional digital image correlation. The test data is then aggregated, time-synchronized, and post-processed, allowing for the examination of the electromechanical response of the sample due to a biaxial loading scenario. The efficacy of this test method is examined through monotonic, cyclic, and stretch-and-hold inflation testing of representative, screen-printed conductors on thermoplastic polyurethane substrates. Results are discussed, along with the underlying physical phenomena governing the general test approach, and recommendations are made for extensions of this work.