Influence of fingerprints and finger positioning on accuracy of RF blood glucose measurement from fingertips

Non‐invasive blood glucose measurement has attracted great interest from researchers deploying various techniques where microwave sensing is one of them. Microwave resonators are utilised as sensors for measuring the glucose levels. A body part is placed on the sensor for a reading and the measurement principle lies in the change of the dielectric properties of blood with varying levels of glucose. The fingertip is a popular measurement site as there is a good amount of fresh blood supply. The position of the fingertip on the sensor has an effect on the sensor response due to the change in the propagation path of the EM field inside the finger. Moreover, fingerprints also affect the sensor response as the irregular ridges and valleys in the fingerprint introduce air gaps altering the effective permittivity seen by the sensor. The effects of fingerprints as well as finger positioning on the sensor is explored and explained.