Elastomeric Optical Waveguides by Extrusion Printing

Abstract

Advances in optogenetics and the increasing use of implantable devices for therapies and health monitoring are driving demand for compliant, biocompatible optical waveguides and scalable methods for their manufacture. Molding, thermal drawing, and dip‐coating are the most prevalent approaches in recent literature. Here the authors demonstrate that extrusion printing at room temperature can be used for continuous fabrication of compliant optical waveguides with polydimethylsiloxane (PDMS) core and crosslinked Pluronic F127‐diacrylate (Pluronic‐DA) cladding. The optical fibers are printed from fluid precursor inks and stabilized by physical interactions and photoinitiated crosslinking in the Pluronic‐DA. The printed fibers show optical loss values of 0.13–0.34 dB cm–1 in air and tissue within the wavelength range of 405–520 nm. The fibers have a Young's Modulus (Pluronic cladding) of 150 kPa and can be stretched to more than 5 times their length. The optical loss of the fibers shows little variation with extension. This work demonstrates how printing can simplify the fabrication of compliant and stretchable devices from materials approved for clinical use. These can be of interest for optogenetic or photopharmacology applications in extensible tissues, like muscles or heart.

Soft Optical Waveguides for Biomedical Applications, Wearable Devices, and Soft Robotics: A Review

“…Single core (silk) Printing [39] Film (chitosan)/substrate (sodium silicate glass) Spin coating [40] Single core (recombinant spider silk protein) Molding [41] Elastomer waveguides Core (PDMS-5:1)/cladding (PDMS-20:1) Mold injection and dip coating [64] Core (polyurethane rubber)/cladding (silicone composite) 3D-printed molding [66] Core (PDMS)/cladding (pluronic F127-diacrylate) Coaxial extrusion [24] Liquid core waveguides Core (UV curable hybrid polymer)/cladding (aqueous triblock copolymer) Coaxial extrusion [47] light transmission in a single-layer waveguide is susceptible to changes in the refractive index of the surrounding medium.…”

“…In addition to the previous methods, soft optical waveguides with regular structure can be easily formed by the extrusion of long filaments, making this method particularly suitable for manufacturing long soft waveguides. [24,47,61,67] Encouraging results have been achieved through the combination of filaments extrusion and 3D-printing technology for fabricating soft optical waveguides. [68] Heiden et al 3D printed gelatin-based hydrogel (biogel) inks into dimensionally stable complex objects to form stretchable optical waveguides, as shown in Figure 1d.…”

“…[16][17][18][19] Soft optical waveguides not only exhibit a remarkable resistance to electromagnetic interference but also offer exceptional flexibility and durability. In particular, compared with chemically non-biocompatible soft materials, soft optical waveguides utilize biocompatible materials, such as hydrogels, naturally derived polymers and elastomers, [20][21][22][23][24][25][26] making them particularly suitable for long-term wear or implantable applications within the human body. Additionally, soft waveguides use light as a carrier of information and energy, enabling highly sensitive sensing and actuation in multiple dimensions (mechanical, thermal, biochemical, etc.…”