Many diagnostic devices and methods perform an invasive test requiring a blood sample to be extracted from an end user.  For example, most commercially-available portable blood glucose meters require an end user to prick his/her finger with a lancet to perform a blood glucose level test.  After pricking his/her finger, the end user deposits a drop of blood onto a test strip.  The sample of blood on the test strip is tested by the glucose meter to determine a glucose level.  Since a typical end user with diabetes performs the above-described invasive test four times a day, the need exists for a noninvasive apparatus to perform blood glucose level tests. 
HIV testing is another diagnostic procedure which uses an invasively-extracted sample of blood.  This procedure and other diagnostic procedures also would benefit from a noninvasive apparatus designed therefor.