Linearization Technique for Dual-Wavelength CW Photoacoustic Detection of Glucose

We present photoacoustic glucose detection based on a continuous-wave-modulated differential method with a linearization technique. To improve the linearity of photoacoustic signal to glucose concentration, one of the two photoacoustic signals is simply used to normalize the variations in the acoustic properties in a differential signal. This easy and fast technique enables us to perform temperature compensation using an acoustic signal from water. Measured results for glucose solutions (0-2 g/dL) show that the differential signal has an excellent linear correlation (R = 0.998) with the glucose concentration and good repeatability (a sensitivity of 1.61%/g·dL
^-1
and a detection limit of 120 mg/dL). We also investigate the influence of optical scattering on the sensitivity to glucose in a turbid media. Measured results for glucose in intralipid solutions suggest that this method provides comparable sensitivity (1.26%/g·dL
^-1
for intralipid 2% solution) even in a scattering medium such as skin. Results indicate that the technique could offer high tolerance to optical scattering in biological tissues.