Foldable and Cytocompatible Sol-gel TiO2 Photonics.

Area of Science:

• Biophotonics
• Materials Science
• Biomedical Engineering

Background:

• Integrated photonics offers miniaturized platforms for light-tissue interaction in biomedical applications.
• The mechanical rigidity and cytotoxicity of traditional materials hinder integration with soft biological tissues.
• There is a need for flexible, biocompatible materials for advanced biophotonic devices.

Purpose of the Study:

• To present amorphous titanium dioxide (TiO2) thin films as a viable material for flexible and biocompatible integrated photonics.
• To demonstrate the fabrication of flexible optical waveguides and resonators using sol-gel TiO2.
• To assess the mechanical flexibility and cytotoxicity of the developed TiO2-based biophotonic devices.

Main Methods:

• Amorphous TiO2 films were deposited using a low-temperature (<250°C) sol-gel process on plastic substrates.
• High-index-contrast flexible optical waveguides and resonators were fabricated.
• Mechanical flexibility was tested using a multi-neutral-axis design, and optical performance was measured.
• In-vitro cell culture tests were performed to evaluate cytotoxicity.

Main Results:

• Sol-gel TiO2 films were successfully deposited and used to fabricate flexible optical waveguides and resonators.
• Resonator quality factors up to 20,000 were achieved.
• The devices demonstrated remarkable mechanical flexibility, sustaining repeated folding without performance degradation.
• In-vitro tests confirmed the low cytotoxicity of the sol-gel TiO2 devices.

Conclusions:

• Sol-gel derived amorphous TiO2 is a promising material for flexible and biocompatible integrated photonics.
• This material platform enables the development of novel biophotonic devices for diverse biomedical applications.
• The combination of optical performance, mechanical flexibility, and biocompatibility opens new avenues in biophotonics.