Transparent piezoelectric film as photoacoustic sensor for glucose measurement.

Abstract

Photoacoustic spectroscopy is an alternative technique for noninvasive glucose monitoring in diabetic patients. The near-infrared light irradiation penetrates a few millimeters into human tissue and an acoustic wave derived from the optical absorption is generated. The photoacoustic signal is detected by a piezoelectric transducer, and the glucose concentration in the human tissue is estimated from the magnitude of the signal. The irradiation geometry is crucial when photoacoustic signals are acquired with a transducer. Irradiation close to the center of the transducer is preferable because the fluence in the tissue decays exponentially with distance. However most transducers have with a narrow angular aperture along the axis of irradiation, because the irradiation is affected by the transducer dimensions. Herein, a photoacoustic sensor using a piezo film transparent in the near-infrared to irradiate tissue directly below the transducer is described. The capability of the proposed system was tested using a pure glucose tablet.