Photoacoustic microscopy (PAM) exploits the optical absorption spectrum unique to tissue types to produce ultrasonic waves that produce images. Resolution of the PAM system is dependent on the frequency of the ultrasound transducer. The current system uses a 25MHz ultrasound transducer that achieves a resolution of 60 µm. In this project, a higher frequency transducer was fabricated using a 24 µm PVDF (poly-vinylidene fluoride) film to improve the resolution of the PAM system.
I propose a method for constructing a PVDF ultrasound transducer. A non-conductive epoxy backing was used as a backing plug to absorb the ultrasound. Electrical connections with the BNC cable were established using conductive epoxy and copper wires. Subsequently, the transducer was acoustically and electrically characterized. With this data, the center frequency (34MHz) and bandwidth (6dB bandwidth of 23 MHz) were measured, and the transducer was electrically tuned to ensure better pulse energy delivery. Finally, the transducer was placed in the PAM system to create images of lipid phantoms.