Sensors have become key elements of today’s society. We live surrounded by sensors and the society evolves towards generalised and personalised sensorization, which allows a greater availability of data to interact with. However, sensors technology is limited in the field of biosensing, where there are no solutions that include universal and versatile label-free detection systems. A particular case consist of the detection of microRNA (microRNAs or miRNAs are short non-coding RNA single strands that can facilitate the early diagnosis or control of an illness as well as be used for therapeutic purposes), which requires the utilisation of expensive, complex and massive analysis techniques. Here, the question arises whether it is possible to design a unified sensing architecture that can be used for the detection of biological species of different molecular weight or chain length as in the case of DNA and RNA. The answer to these challenges consists of the utilization of label-free fiber optic sensors based on Lossy Mode Resonances (LMRs) and their superior performance with more than 1,000,000 nm/RIU (refractive index units) or, in other words, a record sensitivity of 9.19•10-10 RIU when using a typical 1 pm resolution optical spectrum analyser.

The exceptional performance of fiber optic LMR based sensors, already demonstrated in many refractometric applications, plays a key role thanks to the inherent capabilities of the fiber, such as small size, light weight, biocompatibility and immunity to electromagnetic interferences among others. LMR technology is also at an advanced stage but the real challenge here consists of the adequate preparation (activation and functionalisation) of the substrate in order to adjust the selectivity of the device to the specific targets (miRNAs). The main objective behind this proposal consists of developing, testing and validating fiber optic sensors based on LMR for biosensing applications through the adequate selection of specific biomarkers in blood, serum or saliva associated to rheumatic diseases.

The interdisciplinary nature of this proposal includes a profound knowledge of photonics, nanotechnology, material characterisation and biomedical diagnosis for the development of extremely sensitive and selective fiber optic biosensors by means of the utilisation of LMR technology. In particular, the validation of the proposed approach would enable to probe the capability of this technology to be transferred from the labs to the end user so that it is possible to obtain a robust, compact, easy to handle and, hopefully, small enough device to put it comfortably on the palm of our hand. Novel devices to such a point that they are in conditions to compete in a short-term period with other technologies with the additional advantages offered by optical based devices. So probably it is time to take the next step and save thousands of lives and billions of euros in healthcare costs.