SUPPLEMENTAL DEVICE FOR USE WITH AN INJECTION DEVICE, A METHOD OF OPERATION THEREOF, AND A COMPUTER PROGRAM FOR CONTROLLING A SUPPLEMENTAL DEVICE TO PERFORM THE METHOD
A supplemental device for use with an injection device, the supplemental device comprising: a plurality of light sources each being configured to illuminate a surface portion of an injection device, in use, with light of a different wavelength at least one sensor for generating sensor outputs indicative of the respective intensities of light of different wavelengths reflected from the surface portion and a processor for: controlling the plurality of light sources to illuminate the surface portion with light of first to third different wavelengths obtaining first to third values for sensor outputs corresponding to the first to third different wavelengths respectively performing one or more calculations using at least the first and second values to provide one or more further values and using the third value and the or each further value, but not the first and second values, to determine a property of the injection device.
