Researchers conducted extensive literature research, and systematically summarized and compared the sensing abilities of optical refractive index sensors according to their sensitivities and figure of merits. A 3-D technology map was then established to define the standard and development trend for optical refractive index sensors using plasmonic and photonic structures.
The technology map, just like a searchlight, clearly indicates the sensing ability, merits, and shortcomings of different categories of optical refractive index sensors for researchers in the field.
Any newly developed optical refractive index sensors can be added to this technology map to compare their sensing abilities with prior works. The continuous addition of new plasmonic and photonic refractive index sensors will enrich the technology map, thus providing a benchmark for this rapid development of optical refractive index sensors.
Bearing the map in mind and thoroughly understanding the merits, limitations, mechanisms, and development trends of different categories of RI sensors, together, the researchers can advance the field more effectively.
With the technology map, various optical refractive index sensors could be better selected according to different applications. Such a comprehensive review of optical refractive index sensors with plasmonic and photonic structures will attract much attention in the research communities, which will help engineers to use the right sensors for the design of sub-systems in smart cities and IoT.