Gas-Permeable, Irritation-Free, Transparent Hydrogel Contact Lens Devices with Metal-Coated Nanofiber Mesh for Eye Interfacing

Abstract

An electronic “smart” contact lens device with high gas permeability and optical transparency, as well as mechanical compliance and robustness, offers daily wear capability in eye interfacing and can have broad applications ranging from ocular diagnosis to augmented reality. Most existing contact lens electronics utilize gas-impermeable substrates, electronic components, and interfacial adhesion layers, which impedes them from applications requiring continuous daily wear. Here we report on the design and fabrication of an eye interfacing device with a commercial ocular contact lens as the substrate, metal-coated nanofiber mesh as the conductor, and in situ electrochemically deposited poly­(3,4-ethylenedioxythiophene) (PEDOT) /poly­(styrene sulfonate) (PSS) as the adhesion material. This hydrogel contact lens device shows high gas permeability, wettability, and level of hydration, in addition to excellent optical transparency, mechanical compliance, and robustness. Using a rabbit model, we found that the animals wearing these hydrogel contact lens devices continuously for 12 hours showed a level of corneal fluorescein staining comparable to those wearing pure hydrogel contact lenses for same period of time, with no obvious corneal abrasion or irritation, indicating their high level of safety for continuous daily wear. Finally, full-field electroretinogram (ERG) recordings on rabbits were carried out to demonstrate the functionality of this device. We believe that the strategy of integrating nanofiber mesh-based electronic components demonstrated here can offer a general platform for hydrogel electronics with the advantages of preserving the physiological and mechanical properties of the hydrogel, thus enabling seamless integration with biological tissues and providing various wearable or implantable sensors with improved biocompatibility for health monitoring or medical treatment.

Advances and current challenges in non‐invasive wearable sensors and wearable biosensors—A mini‐review

“…In order to succeed the ocular WBS uses, it will be necessary not to interfere with the transparency and flexibility conditions of the contact lenses and nor to affect the optical necessities (Kim, Kukjoo, et al, 2019; Wei et al, 2019). The electronics compounds incorporated must be capable of having their mechanical, chemical and electrical properties for a highly sensitive, selective and wireless response, which needs to be connected in real time with the user by a computer or a smartphone (Takamatsu et al, 2019).…”

“…essary not to interfere with the transparency and flexibility conditions of the contact lenses and nor to affect the optical necessities(Kim, Kukjoo, et al, 2019;Wei et al, 2019). The F I G U R E 5 Epidermal WBS: All images were reproduced with authors' permission and respective works are referred.…”

Design and Fabrication of Photo-Responsive Hydrogel for the Application of Functional Contact Lens

“…Since the emergence of poly(hydroxyethyl methylacrylate) (pHEMA) hydrogel as soft contact lenses in the 1960s, the swollen soft materials became favorites in the materials field on account of having a similar microenvironment to the biological system (Hao et al, 2011;Hu and Gong, 2016;Hoteling et al, 2018;Samsom et al, 2018;Lorente-Velazquez et al, 2019;Wei et al, 2019). Traditional hydrogel contact lenses were synthesized by some hydrophilic monomers (containing such as hydroxy, carboxyl groups, different from hydrophobic groups like alkyl groups) like HEMA, vinyl pyrrolidone (NVP), acrylamide (AA) with excellent transparency, controllable water content, and certain non-deformability (Hoteling et al, 2018;Samsom et al, 2018;Lorente-Velazquez et al, 2019;Tong et al, 2019;Wei et al, 2019;Guan et al, 2020;Wei et al, 2020). However, these early synthesized hydrogels had some original drawbacks due to their structure and properties.…”

“…Typically, an aqueous microenvironment also benefits bacterial reproduction, which would induce eye infection (Hoteling et al, 2018;Samsom et al, 2018;Lorente-Velazquez et al, 2019;Wei et al, 2019). Recently, with the development of regeneration medicine, traditional hydrogels were explored for new applications as drug carriers/ hydrogel scaffolds (Hao et al, 2011;Hu and Gong, 2016;Hoteling et al, 2018;Samsom et al, 2018;Lorente-Velazquez et al, 2019;Wei et al, 2019). While these new applications put forward new requests for tradition hydrogels, among these requests, the control unit seems especially relevant for its application.…”

All-printed stretchable corneal sensor on soft contact lenses for noninvasive and painless ocular electrodiagnosis

“…Other side effects have been also reported, including foreign body sensation, eye pain, superficial punctate keratitis, corneal epithelial defects, and conjunctival erythema 15 . More recently, several ongoing research endeavors have helped enable the successful fabrication of a range of flexible sensors on a custom-built contact lens made from several polymers (e.g., hydrogel silicones, Parylene-C, or SU8 resins) and functional nanomaterials (e.g., graphene and metallic nanowires) [16][17][18][19] . These newer devices have shown some initial success at the laboratory scale, but their practical application in human eyes remains impeded due to the lack of mechanical reliability (for lens handling, fitting, cleaning, and inadvertent eye rubbing), chemical stability (for long-term lens storage and multiple disinfection cycles), and oxygen transmissibility.…”