Surface Plasmon Resonance Sensor of CO2 for Indoors and Outdoors Pérez Ocón, Francisco De Asís Pozo Molina, Antonio Manuel Cortina, Jorge Rabaza Castillo, Ovidio CO2 sensor Nanostructures Plasmonic sensor The ability to detect CO2 with the smallest possible devices, equipped with alarms and having great precision, is vital for human life, whether indoors or outdoors. It is essential to know if we are being subjected to this gas to establish the level of ventilation in factories, houses, classrooms, etc., and to be protected against viruses or dangerous gas concentrations. Equally, when we are in the countryside, it is useful to be able to evaluate if the greenhouse effect, caused by this gas, is increasing. We propose a surface plasmon resonance (SPR) sensor for the measurement of CO2 concentrations taking into account that the refractive index of carbon dioxide depends on temperature, humidity, pressure, etc. With our sensor we can measure (in air) in any type of environment and concentration. Our sensor has a resolution of 5.15 × 10−5 RIU and a sensitivity of 19.4 RIU−1 for 400 ppm. 2021-07-30T08:18:22Z 2021-07-30T08:18:22Z 2021 journal article Pérez-Ocón, F.; Pozo, A.M.; Cortina, J.; Rabaza, O. Surface Plasmon Resonance Sensor of CO2 for Indoors and Outdoors. Appl. Sci. 2021, 11, 6869. https://doi.org/ 10.3390/app11156869 http://hdl.handle.net/10481/69993 10.3390/app11156869 eng http://creativecommons.org/licenses/by/3.0/es/ open access Atribución 3.0 España MDPI