Manufacturing of elastomeric substrates for stretchable printed electronics

ABSTRACT Stretchable electronics are being used in applications such as wearable electronics, robotic skin, wearable health-monitoring devices, and smart textiles due to their excellent mechanical conformability through stretching, flexing, twisting, and folding. This work focuses on creating printable stretchable substrates based on butyl rubber (IIR), combined with a ferroelectric filler, barium strontium titanate (BST). BST has unique properties, including the ability to tune the dielectric properties by applying a bias to the substrate. A high loading of BST was incorporated to tailor the dielectric properties of the substrate. This work investigated the effect of three different cure systems on the properties, including interaction with a silver ink. For all cure systems, cure and scorch time decreased with increases in BST loading. A phenolic cure did not affect the ink conductivity, whereas the sulfur-cured systems resulted in nonconductive ink. For the phenolic-cured substrate, the tensile strength increased and the elongation decreased with increasing filler loading. The elastomer could be filled with up to 40 vol. % BST while still maintaining elongation greater than 200%.