If this were used for blood, it would be invasive, because the blood must be extracted with needles, exactly like in the current kits for measuring blood glucos

If this were used for blood, it would be invasive, because the blood must be extracted with needles, exactly like in the current kits for measuring blood glucose. The gel holder would substitute the sensitive strips that are used in such glucose measurement kits and the smartphone would replace the electronic reader that displays the results. Nothing would change about the invasiveness of having to pierce the skin with needles, to extract blood. There exist experimental devices for non-invasive measurement of the blood glucose, whose purpose is to avoid the use of piercing needles, but this new glucose sensor has nothing to do with those. This new glucose sensor is for other uses and its advantage is that it no longer needs a special expensive electronic device for reading the sensor output, but a standard smartphone is good enough.