A stretchable platform with spherical-shaped electronics based on thermo-
plastic polyurethane (TPU) is introduced for soft smart contact lenses. The
low glass transition temperature of TPU, its relatively low hardness, and its
proven biocompatibility (i.e., protection of exterior body wounds) fulfill the
essential requirements for eye wearable devices. These requirements include
optical transparency, conformal fitting, and flexibility comparable with soft
contact lenses (e.g., hydrogel-based). Moreover, the viscoelastic nature of
TPU allows planar structures to be thermoformed into spherical caps with a
well-defined curvature (i.e., eye’s curvature at the cornea: 9 mm). Numerical
modeling and experimental validation enable fine-tuning of the thermo -
forming parameters and the optimization of strain-release patterns. Such
tight control is proven necessary to achieve oxygen permeable, thin, nonde-
velopable, and wrinkle-free contact lenses with integrated electronics (silicon
die, radio-frequency antenna, and stretchable thin-film interconnections). This
work paves the way toward fully autonomous smart contact lenses potentially
for vision correction or sensing applications, among others
