Parylene photonics: a flexible, broadband optical waveguide platform with integrated micromirrors for biointerfaces

Abstract

Targeted light delivery into biological tissue is needed in applications such as optogenetic stimulation of the brain and in vivo functional or structural imaging of tissue. These applications require very compact, soft, and flexible implants that minimize damage to the tissue. Here, we demonstrate a novel implantable photonic platform based on a high-density, flexible array of ultracompact (30 μm × 5 μm), low-loss (3.2 dB/cm at λ = 680 nm, 4.1 dB/cm at λ = 633 nm, 4.9 dB/cm at λ = 532 nm, 6.1 dB/cm at λ = 450 nm) optical waveguides composed of biocompatible polymers Parylene C and polydimethylsiloxane (PDMS). This photonic platform features unique embedded input/output micromirrors that redirect light from the waveguides perpendicularly to the surface of the array for localized, patterned illumination in tissue. This architecture enables the design of a fully flexible, compact integrated photonic system for applications such as in vivo chronic optogenetic stimulation of brain activity.

Waveguides: Delivering light into tissue

A flexible and biocompatible optical platform is demonstrated that can be used for biophotonic applications. Delivering light into tissue is important for biological imaging and manipulation, such as for medical treatments or monitoring brain activity. However, traditional light delivery systems are composed of rigid materials, which can damage biological tissue. Here, a team from Carnegie Mellon University led by Maysamreza Chamanzar demonstrates a photonic platform composed of biocompatible and mechanically flexible polymeric optical waveguides, termed Parylene photonics. This platform features embedded micromirrors that enable targeted light delivery to specific locations within the tissue. They show that this system can efficiently deliver light with a soft and flexible device, demonstrating its potential as a platform for biointerfacing.