Experimental Characterization of a Piezoelectric Transducer for Integration into a Photoacoustic System

Photoacoustic imaging (PAI) is a medical imaging modality that has been gaining relevance in the last decade due to its potential to safely acquire images, ranging from organelles to organs, without radiation. PAI uses the best features of both optical and acoustic methods. In this methodology, the target tissue is excited by a light source, triggering a local temperature rise in the tissue, which generates ultrasonic waves that are subsequently acquired by an ultrasound transducer. This hybrid modality allows a wide range of potential applications, namely in clinical medicine, preclinical research, and biology. This work aims at the experimental characterization of a piezoelectric transducer, towards developing the detection module of a photoacoustic system for biomolecule monitoring. Throughout the characterization of the transducers, we analyzed the resonance frequency, the reflection coefficient, and the outputted voltage amplitude. The electrical characterization showed resonance frequencies of 89 kHz and 4 MHz in the radial and longitudinal directions, respectively, which agree with the theory. Experimentally, by evaluating the acoustic propagation between an emitting and a receiving transducer, it was possible to observe a linear relationship between the amplitude of the emitted and received waves. In contrast, the amplitude of the received wave varies inversely with the distance between the transducers.