Engineered optical fibers for deep-tissue applications

Abstract

High-precision optical diagnostics and therapy in deep tissues are hindered by light scattering and absorption. Engineered optical fibers, serving as minimally invasive optical fibers, provide a powerful platform to bypass these barriers. This review systematically deconstructs the design of these advanced fibers from the unified perspectives of materials science and structural engineering. First, key material systems are analyzed—from traditional silica to emerging polymers and hydrogels—evaluating how their intrinsic properties dictate the fiber's optical performance, mechanical compliance, and biocompatibility. Then, critical structural paradigms are examined, including propagation modes, refractive index profiles, and core geometries, elucidating how these designs control features such as signal fidelity, resolution, and functional integration. The review further considers how the fiber's potential is amplified by auxiliary front-end physical modulation and back-end computational reconstruction techniques. Building on this foundational framework, the application of these engineered fibers is comprehensively surveyed in state-of-the-art biomedical diagnostics, such as endoscopic imaging and biosensing, and in targeted therapeutics, including optogenetics, phototherapies, and drug delivery. Ultimately, by systematically linking engineering principles to biomedical functions, this review establishes a foundational framework for designing next-generation, clinically focused fiber-optic systems, concluding with a critical assessment of prevailing challenges to illuminate future research directions in this burgeoning field .