arXiv subjects

Asad Nauman

Publications and source records attributed to Asad Nauman.

2 recordsLinked to original sources

arXiv2026

Digitally Programmable Photochromic Hydrogel Contact Lenses as Light-Adaptive Artificial Irises

Excessive exposure to ultraviolet (UV) radiation is associated with a range of ocular pathologies, motivating the development of soft optical devices that can dynamically regulate incident light. In the human eye, this adaptive optical functionality is performed by the iris, which modulates pupil size to control retinal irradiance in response to ambient illumination. Here we present a photochromic contact lens based artificial iris that mimics this biological light-adaptation mechanism through reversible, spatially programmable modulation of optical transmission with intrinsic UV blocking. Photochromic dyes are embedded within a biocompatible hydrogel matrix, while the cross-linked network is patterned using a digital micromirror device (DMD)based grayscale UV lithography to encode controlled radial gradients in dye switching. This approach generates iris-like attenuation profiles that emulate pupil-dependent light regulation while enabling customizable iris geometries and transmission patterns. The resulting lenses exhibit rapid and reversible UV-induced darkening with position-dependent kinetics, enabling continuous modulation of transmitted light. The photoresponse remains stable over repeated activation cycles without measurable fatigue. The patterned lenses maintain mechanical stability, controlled swelling, and wettability suitable for contact lens applications. This platform combines programmable photochromism and hydrogel optics to enable light-adaptive lenses that mimic key functions of the human iris.

physics.optics↗

arXiv2026

Zero-Poisson Ratio Elastomeric Substrates for Distortion-Free Stretchable Displays

Stretchable displays are critical for emerging wearable electronics, soft sensors, and next-generation AR/VR interfaces. Although recent advances have enabled foldable, twistable, and rollable displays, intrinsically stretchable substrates often exhibit significant lateral contraction under tensile strain due to their high Poisson ratio, leading to unintended wrapping, distortion, and shrinkage. Here, we report a transparent heterogeneous-modulus elastomeric substrate designed to achieve near-zero Poisson ratio while maintaining mechanical softness and optical transparency. The substrate consists of line-patterned hard polydimethylsiloxane (PDMS) embedded within a soft PDMS matrix, producing spatially heterogeneous strain distribution during stretching. In this architecture, the soft PDMS functions as a strain-absorbing medium, while the embedded hard PDMS patterns suppress lateral deformation perpendicular to the applied strain. As a result, the structure significantly dampens transverse contraction and realizes a near-zero effective Poisson ratio. To demonstrate the utility of this platform for stretchable optoelectronics, LED arrays were integrated onto the heterogeneous substrate. The devices exhibit minimal vertical and lateral distortion during tensile deformation, enabling mechanically stable operation of stretchable light-emitting displays. This heterogeneous modulus strategy provides a simple, scalable approach to mechanically robust stretchable display platforms.

physics.optics↗