Printed Soft Optical Waveguides of PLA Copolymers for Guiding Light into Tissue

The application of
optical technologies in treating pathologies
and monitoring disease states requires the development of soft, minimal
invasive and implantable devices to deliver light to tissues inside
the body. Here, we present soft and degradable optical waveguides
from poly­(d,l-lactide) and derived copolymers fabricated
by extrusion printing in the desired dimensions and shapes. The obtained
optical waveguides propagate VIS to NIR light in air and in tissue
at penetration depths of tens of centimeters. Besides, the printed
waveguides have elastomeric properties at body temperature and show
softness and flexibility in the range relevant for implantable devices
in soft organs. Printed waveguides were able to guide light across
8 cm tissue and activate photocleavage chemical reactions in a photoresponsive
hydrogel (in vitro). The simplicity and flexibility of the fiber processing
method and the optical and mechanical performance of the obtained
waveguides exemplify how rational study of medically approved biomaterials
can lead to useful inks for printing cost-effective and flexible optical
components for potential use in medical contexts.