Abstract: The present disclosure relates to methods for detecting a biological parameter and to sensors for detecting a biological parameter. Certain embodiments of the present disclosure provide a method of detecting a biological parameter in a subject, the method comprising: implanting a sensor into the subject, wherein the sensor comprises an optical reflectance property between 400 and 1200 nm which is responsive to the biological parameter; detecting an optical reflectance property between 400 and 1200 nm through the skin of the subject from the implanted sensor, and using the optical reflectance property to detect the biological parameter.