Analyte sensor component

A sensor component for use in a system for measuring the concentration of one or more analytes in fluid in a fluid line, the sensor component comprising:

• one or more sensing elements having an optical property that varies with the concentration of the one or more analytes in the fluid, the sensor component being configured to engage with the fluid line such that the sensing elements are exposed to the fluid in the fluid line when the sensor component is engaged with the fluid line;
• a connector configured to connect to one or more optical waveguides, the sensor component being configured to transmit light between the one or more optical waveguides and the one or more sensing elements;
• a reflective element, wherein:
• the sensor component is configured to transmit the light between the one or more optical waveguides and the reflective element;
• the reflective element is configured to reflect at least 10% of light incident thereon back to the one or more waveguides;
• and
• the light transmitted by the sensor component between the one or more optical waveguides and the reflective element has a different wavelength to the light transmitted between the one or more optical waveguides and the one or more sensing elements.