Optical Fibre Gas Sensor

About

While low cost gas sensors are widely available, these are often dedicated to a single gas and require an electrical current to function. This means multiple sensors are needed in many applications, and these sensors can pose a risk of igniting flammable gases. Sensors for multiple gases are available but expensive. There is a need therefore for sensors that detect multiple gases, have no requirement for current at the sensing head, and are available at a reasonable cost. The invention uses localised surface plasmon resonance effects to detect the presence of gases in the environment. The device comprises an optical waveguide with refractive index modulations and an outer surface plasmon-supporting layer made up of a nanomaterial. The nanomaterial formulation and its structure provide a surface that attracts gases. The refractive index modulations excite the surface plasmons as the radiation passes through the optical waveguide. The binding of the gas to the nanomaterial alters the surface plasmon resonance effect, causing a change in the strength and wavelength of the light coupled out from the waveguide. The wavelength and intensity of the radiation indicates the presence of the gas and its concentration. At present the sensor is dedicated to CO2, but could potentially detect multiple gases with a single detector head. Crucially the sensor head requires no electrical current and could offer a low-cost solution.