High refractive index (RI) NIL resins containing titania nano-particles (NPs) can be used for a wide field of view in augmented reality, virtual reality, mixed reality (AR/VR/MR) devices, but their use is limited by their high reactivity in sunlight. ACW now shows that sunlight damage of these NIL resins can be prevented by hermetically sealing the devices in an oxygen- and water-free environment.
NIL resins containing unshielded titania NPs are degraded by sunlight within hours, and NIL resins containing shielded titania NPs are degraded within days. When hermetically sealed in a nitrogen atmosphere, however, both types of NIL resins were shown to survive the equivalent of half a year of normal sunlight exposure with virtually no damage as judged on a bulk scale from an unchanging RI and thickness. Similarly, AFM and SEM studies demonstrated on the nanometer scale that imprinted titania NP NIL resins with 400 nm high and 300 nm wide gratings displayed considerable damage from hours of sunlight exposure when open to the atmosphere but no noticeable damage from months of sunlight exposure when contained in hermetically sealed encasements.
For more information, see the ACW whitepaper describing the hermetic sealing studies.