Cellulose Optical Fibers for Advanced Sensing Applications

Description

Since their invention in the mid-20th century, optical fibers (OFs) have become a key component in modern photonics. Glass optical fibres (GOFs) and polymer optical fibers (POFs) are the two main classes of fibers dominating the current commercial sphere. However, recently a novel candidate material has entered the OF domain, viz. cellulose. Optical fibers derived from cellulose-based materials offer exciting features such as renewability, biocompatibility, and biodegradability. Conventional OFs lack such features. However, there is more to cellulose based OFs than offering sustainability. Cellulose OFs can work as ‘active’ sensing components because they are able to interact with their surroundings. For instance, they can sense touch, humidity, and liquids. Sensing such changes enables us to derive a multitude of sensing applications from OFs.
In the present work, we prepared OFs from carboxymethyl cellulose (CMC) and employed those in various sensing systems. OFs were fabricated via wet-spinning of aqueous CMC hydrogel filaments into a coagulation bath containing aluminium sulphate. The hydrogel fibers were crosslinked with Al3+ ions and dried in air to obtain fibers in a core-only architecture. CMC fibers were optically transparent and exhibited high tensile strength (150 MPa) and low fracture elongation (<5%). Further, we studied the waveguiding properties of the CMC OFs where spectral measurements showed that the light transmission window for the CMC fibers was in the range of 550-1350 nm, wherein, the minimum attenuation coefficient for CMC fibers was measured to be 1.6 dB.cm-1 (637 nm). CMC optical fibers were then applied in touch sensing and respiratory rate monitoring. Finally, we demonstrated high-speed (150 Mbit/s) optical signal transmission using CMC fibers (at a typical telecommunication wavelength 1310 nm) in both air and water media. Our results indicate towards the potential of CMC-based biocompatible OFs for highly demanding advanced sensor applications, such as in the biomedical domain.

Period	13 Jun 2022 → 17 Jun 2022
Event title	International Conference on Nanotechnology for Renewable Materials: TAPPI Nano 2022
Event type	Conference
Location	Helsinki, FinlandShow on map
Degree of Recognition	International