• Verplancke, Rik
• Vanfleteren, Jan
• Smet, Herbert De
• Vásquez Quintero, Andrés

Abstract

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

Topics

• impedance spectroscopy
• polymer
• Oxygen
• glass
• glass
• hardness
• glass transition temperature
• forming
• biocompatibility