Microfluidic wet spinning of soft polydimethylsiloxane polymer optical fibers

Polymer optical fibers (POFs) are an essential component of photonic textile sensors for the development of healthcare@home technologies. However, fabricating tailored POFs exhibiting the required properties for such applications remains challenging. Here, an innovative method to fabricate soft POFs based on polydimethylsiloxane is introduced: the hydrogel-assisted microfluidic wet spinning (HA-MWS) technology. Combined with a straightforward post-processing step, the HA-MWS enabled the production of soft POFs with tailored moduli (0.35 MPa to 5.0 MPa), low surface roughness ($R_q<$ 6 nm), and, consequently, low attenuation (<0.25 dB/cm). The quasi-static and dynamic mechanical, chemical, optical, thermal, and surface properties of the soft POFs produced by HA-MWS were investigated in detail. A photonic textile sensor demonstrator was built with these soft POFs with tailored pressure sensitivity in the range of 2–300 kPa, modulus close to that of skin, and high-temperature stability between -30 ${}^{\circ }C$ and 90 ${}^{\circ }C$. This methodology can potentially become a standard tool for designing POFs with tunable properties for healthcare monitoring, soft robotics, and biomedicine applications.