Hydrogel Coating Enabling Mechanically Friendly, Step‐Index, Functionalized Optical Fiber

Abstract

Modern medicine, including minimally invasive surgeries, relies on optical fibers to efficiently transmit light into the human body. However, existing optical fibers exhibit poor mechanical compatibility with tissues and insufficient functionality. Herein is shown that a thin layer of hydrogel coating simultaneously improves the performance of optical fibers mechanically, optically, and functionally. By involving the hydrogel as a mechanically friendly skin, the optical fiber achieves surface tissue‐like softness and low friction, without compromising its bulk properties. With high transparency and low refractive index, the hydrogel coating helps form a step‐index profile for low‐loss light transmission. Furthermore, versatile functionalities by hydrogel‐coated optical fibers, like fluorescence generation, photothermal effect, pH sensing, and drug delivery, are conceptually demonstrated. This simple coating/core design that can easily incorporate extraordinary biocompatibility, extreme physical properties, and advanced functionality of hydrogels, will encourage more opportunities for the development of optical fibers in biomedical applications.

Hydrogel-integrated optical fiber sensors and their applications: a comprehensive review

“…Recently, a hybrid PDMS-PAAm structure has been reported with a low attenuation loss of 0.25 dB cm À1 in the visible spectra, by replacing alginate coating. 192 The conventional hydrogel/alginate-integrated core-clad structure demonstrates superior light confinement properties compared to the core-only fiber (Fig. 5f) but cannot facilitate a high refractive index difference between the core and the cladding, which is necessary for low-loss TIR-based light guidance.…”

“…The use of hydrogel materials in sensing applications can improve bio-mechanical compatibility owing to their pivotal features, such as improved softness, lower friction, and flexibility. 192…”

Microfluidic Fabrication of Highly Efficient Hydrogel Optical Fibers for In Vivo Fiber‐Optic Applications

“…Hydrogels are one of the most promising and best‐studied materials for light guiding owing to their advantages such as low modulus and high biocompatibility in biomedical applications. [ 6–21 ] The mechanical and optical properties of the hydrogels can be optimized by tailoring their chemical structure, polymer content, and crosslinking density, allowing the fabrication of highly efficient, soft optical fibers. In addition, they are biocompatible, capable of being integrated into biological tissue on the surface, and can provide the loading for functional guest molecules and diffuse them from the matrix.…”

Liquid-Core Hydrogel Optical Fiber Fluorescence Probes

“…To simplify the preparation as well as to enhance the fluorescence signal collection efficiency, simply and rapidly prepared hydrogel optical fiber fluorescence probes have become a potential solution. − Similar to classical silica optical fibers, hydrogel ones share the same configuration as a high-refractive-index hydrogel fiber core and low-refractive-index hydrogel fiber cladding; therefore, light can be localized and transmitted within the hydrogel fiber core. − Moreover, hydrogel optical fibers can be simply coupled with silica optical fibers and thus are compatible with many existing optical fiber sensing systems. ,, In hydrogel optical fiber fluorescence probes, sensitive materials are often embedded in the solid core. , Because of the porous feature of hydrogels, small-molecule analytes can penetrate into the hydrogel fiber core and react with the embedded sensitive materials. The reaction induces variations in fluorescence signals, which can be localized within the hydrogel fiber core and collected with high efficiency. , For example, various quantum dots (QDs) and fluorescent dyes can be embedded in hydrogel fiber cores to detect metal ions , and explosive picric acid, respectively, because these targets induce significant fluorescence quenching.…”

“…18−20 Moreover, hydrogel optical fibers can be simply coupled with silica optical fibers and thus are compatible with many existing optical fiber sensing systems. 8,21,22 In hydrogel optical fiber fluorescence probes, sensitive materials are often embedded in the solid core. 23,24 Because of the porous feature of hydrogels, smallmolecule analytes can penetrate into the hydrogel fiber core and react with the embedded sensitive materials.…”