The ability to monitor diseases, therapies, and their effects on the body is a critical component of modern care and personalized medicine. Real time monitoring can be achieved by analyzing body fluids or by applying sensors on, or alternatively, inside the body. Implantable sensors, however, must be removed. Second removal procedures lead to further tissue damage, which can be a problem in tissues such as those of the central nervous system. The use of biodegradable sensors alleviates these problems since they do not require removal procedures. Recent advances in material science made it possible for all sensor components to be biodegradable. Small size and power of implants, and the limited selection of materials are the main constraints determining the capabilities of the biodegradable device. Thus, the design will be always a challenge exploring a trade-off among these parameters. Despite of the encouraging results illustrating that biodegradable sensors can be as accurate and reliable as commercially available nondegradable ones, biodegradable implantable sensors are still in their infancy. Significant advances made in this area are critically reviewed in this paper, and future prospects are highlighted.

In this work we demonstrate the advantage of performing the biosensing process of a refractive index optical biosensor under dry conditions, in comparison with the biosensing structure immersed in fluid. We developed a biosensing experiment over a specific transducer based on resonant nanopillars (R-NPs) arrays. The optical interrogation to monitor the recognition events was firstly performed with the R-NPs in dry, only in contact with the air, and secondly with the R-NPs immersed in water. We observed a significant enhance in the sensitivity of the biosensing curve response for the R-NPs in dry conditions, leading an improvement of the Limit of Detection (LoD) in more than one order of magnitude. These results are also in good correlation with 3D-Finite difference time domain simulations carried out for both fluid conditions. According to this result, any interferometric optical bio-transducer for in-situ diagnosis will improve the sensitivity in case it can operate in dry conditions. Moreover, measuring in simple drops of biological samples, in dry conditions, will be a relevant issue for Point of Care Devices.

Despite the remarkable development related to Point-of-Care devices based on optical technology, their difficulties when used outside of research laboratories are notable. In this sense, it would be interesting to ask ourselves what the degree of transferability of the research work to the market is, for example, by analysing the relation between the scientific work developed and the registered one, through patent. In this work, we provide an overview of the state-of-the-art in the sector of optical Point-of-Care devices, not only in the research area but also regarding their transfer to market. To this end, we explored a methodology for searching articles and patents to obtain an indicator that relates to both. This figure of merit to estimate this transfer is based on classifying the relevant research articles in the area and the patents that have been generated from these ones. To delimit the scope of this study, we researched the results of a large enough number of publications in the period from 2015 to 2020, by using keywords “biosensor”, “optic”, and “device” to obtain the most representative articles from Web of Science and Scopus. Then, we classified them according to a particular classification of the optical PoC devices. Once we had this sampling frame, we defined a patent search strategy to cross-link the article with a registered patent (by surfing Google Patents) and classified them accordingly to the categories described. Finally, we proposed a relative figure called Index of Technology Transference (IoTT), which estimates to what extent our findings in science materialized in published articles are protected by patent.