Fluoropolymer‐Single Crystal Nanocomposite Based Transducer Fabrication for Bio‐Imaging

The study presents fabrication of composite polymer materials based transducers for ultrasound and photoacoustic imaging. The transducers have central frequency in the range of 17–42 MHz and bandwidth of more than 70%, which are essential for high resolution imaging. Ultrasound and photoacoustic imaging of phantoms as well as blood vessels containing live RBC is demonstrated.

Abstract

Fluoropolymer alone, as an alternative to lead-based piezoelectric materials, has shown multiple challenges to develop useful sensors for solving real-world problems such as photoacoustic, ultrasound pulse echo, and other non-destructive testing. This work demonstrates the fabrication of high frequency and wide bandwidth transducers with fluoropolymer and highly polarizing cubic single crystal Barium titanate (BaTiO₃) ceramic composite for high resolution in-vivo photo-acoustic and ultrasound imaging. For transducer fabrication, a customized bio-compatible nanocomposite sensor film of PVDF-TrFE (Polyvinylidene fluoride trifluoroethylene)/BaTiO₃ (BTO) is synthesized by drop and dry in heating-cum-electro-poling system for advancing polarization, crystallinity, and higher charge generation. The ratio of nanofiller cubic single crystal BTO and PVDF-TrFE is optimized using characterization techniques such as FTIR, XRD and electrometer. Thereafter, SEM and TGA analyses are performed to study the surface morphology and thermal stability of the sensing film. Transducers with central frequencies varying from 17 to 42MHz are fabricated and tested for both pulse-echo mode and receiving photoacoustic signals. These transducers are used for sensing photoacoustic signals generated from hemoglobin and eumelanin and further for ultrasound and photoacoustic imaging. The imaging results are compared with the results obtained using a commercial ultrasound and photoacoustic imaging device. To the best of the knowledge and available literature, for the first time, the fabrication of ultrasound/photoacoustic transducers with cubic single-crystal nanofiller and fluoropolymer nanocomposite is showed. The detailed transducer fabrication method, characterization results, and imaging of biological tissue using photoacoustic and ultrasound are presented.