New CW-photoacoustic-based protocol for noninvasive and selective determination of aqueous glucose level: A potential alternative towards noninvasive blood sugar sensing

Towards the design of a non-invasive and continuous blood glucose sensor, we chose the continuous-wave photoacoustic (CW-PA) protocol and first developed the frequency shift (FS) method. However, despite linear dependence versus aqueous glucose concentration and potential high sensitivity, the selectivity to glucose remained an important issue. We then proposed a compound-specific complementary protocol that relies on the optical absorption coefficient. By using optical excitation at two π-shifted amplitude-modulated optical wavelengths, and sweeping the optical power of one source, we obtained linear dependence versus glucose and albumin, according to parameter-dependent coefficients. The combination of FS method with this new method at several sets of optical wavelengths then opens the door to selective and sensitive measurement of blood glucose level in a non-invasive and continuous manner.