Diabetes patients need to conduct the “fingerstick” a few times a day. One of the mechanisms of "fingerstick" is to take small amount of blood sample and put it onto a test strip. The enzyme on the test strip reduces the glucose and the electronics of the glucose meter detect the redox species produced. However, this method is painful and increase the risk of infection.
Photonic sensing technology opens up a new method for non-invasive blood glucose concentration. According to an article of medGadget in 2013 (The link follows http://www.medgadget.com/2013/10/non-invasive-measurement-of-blood-glucose-levels-using-glucotrack-interview.html ), the non-invasive kind was invented. By simply clipping onto the earlobe (without puncturing the skin), the blood glucose concentration could be measured. Does anybody knows the working principle for that? Or, suggest a paper describing that?