Stretchable LED matrix display

Stretchable electronics offers a new way for making wearable devices that are unobtrusive and conform to the user's body shape. Electronics manufactured on a stretchable substrate allows integration of electronics into e.g. clothing, disposable patches and wearable accessories while retaining user comfort. This paper presents a LED matrix display manufactured on thermoplastic polyurethane. A 5x17 LED matrix was fabricated with bare die semiconductor LED chips and a reference device with chip scale packaged components. Reliability under stretching is investigated with and without protective measures, namely support adhesive and laminated cover layer. It was found that the bare die samples could withstand no more than 6% strain whereas the packaged components could reach 18%. In a cyclic stretch test the best performance was recorded from a sample laminated with pressure sensitive adhesive, again chip scaled components faring better that the bare dies.