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.

Carbon monoxide (CO) is a highly toxic gas, which can cause death if it is inhaled in small quantities for a long time or in large quantities for a short time. Since this gas can be lethal, it is essential to detect it from minute to large concentrations. Our study consists of the design of a superficial plasmonic resonance (SPR) CO sensor of tiny dimensions which is capable of giving an immediate response at different concentrations. It is designed to work at different heights above sea level since the refractive index of this gas depends on a mixture with air and the air pressure. Due to its low weight and tiny dimensions, it is ideal for space travel or on airplanes. The results show a high resolution and sensitivity (~10−5 RIU of resolution and a sensitivity of 13.51–81.26 RIU−1).