Surface Plasmon Resonance Sensor of CO2 for Indoors and Outdoors

Abstract

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.