Acoustic Modal Analysis of Resonant Photoacoustic Spectroscopy with Dual-Wavelength Differential Detection for Noninvasive Glucose Monitoring

A theoretical study of resonant photoacoustic spectroscopy (PAS) for glucose noninvasive detection was performed by rigorously taking into account the spatial distribution of the photothermal source and the acoustic resonance mode in a cavity. The sensitivity of the dual-wavelength differential PA technique is derived when glucose with weak optical absorption is detected in solution with high optical absorption. The sensitivity dependence of acoustic resonance modes was evaluated by both analysis and experiment with pure water. The analytical results show good agreement with the experiment. The sensitivity against the concentration of the target molecules can be enhanced approximately twofold by choosing the optimum acoustic resonance mode. The results indicate that this method has the potential to detect glucose in a physiological range comparable to that of invasive blood glucose monitoring.