Recently, a team led by Prof. ZHENG Hairong, Prof. QIU Weibao, and Prof. LIU Chengbo from the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, in collaboration with Prof. LI Fei's team from Xi'an Jiaotong University, has developed an ultrasensitive, broadband transparent ultrasonic transducer based on a novel transparent piezoelectric single crystal, achieving high-resolution, large-field-of-view, and rapidphotoacoustic microscopic imaging.

This study was published in Nature Communications on Dec.04.

Owing to the synergistic benefits of optical and acoustic imaging, photoacoustic imaging and acoustic-optical multimodal imaging have emerged as frontier technologies with great potential in the biomedical fields.

However, traditional ultrasonic transducers, being opaque, introduce spatial coupling challenges between the optical and acoustic pathways, resulting in complex imaging systems and issues such as near-field blind spots. Transparent ultrasonic transducers offer a solution by enabling dense integration of acoustic and optical modules, which is crucial for advancing photoacoustic and acoustic-optical multimodal imaging techniques. Yet, the performance of existing transparent ultrasonic transducers has often fallen short compared to their traditional transducers, significantly impacting image quality and thus restricting their practical application.

In this study, researchers used a novel transparent PIN-PMN-PT piezoelectric single crystal, developed through an AC polarization process, as the piezoelectric layer of the transparent ultrasonic transducers. They developed an innovative double-layer acoustic matching system, utilizing quartz glass and epoxy resin, and refined the fabrication process of these acoustic layers. This advancement led to a significant enhancement in ultrasonic transmission efficiency between the transparent transducer and the human body. Additionally, researchers introduced a novel wiring strategy and enhanced the performance ofIndium Tin Oxide (ITO)transparent electrodes, contributing to overall improvements in device functionality and effectiveness.

Owing to these optimizations, the new transparent ultrasonic transducers achieve ultra-high sensitivity (two-way insertion loss of -17.6dB) and – 6dB bandwidth (approximately 80%). The sensitivity of these transducers is 3.5 times higher, and bandwidth 1.3 times broader, compared to those of the current state-of-the-art transparent transducers. This represents a significant advancement in the performance capabilities of such devices.

Furthermore, researchers developed an optical-resolution photoacoustic microscopic imaging system (OR-PAM) based on the new transparent transducers, enabling first-time continuous dynamic imaging of a mouse's cortical microvascular during an epileptic seizure. The system provides high-resolution (micrometer level), large-field-of-view (millimeter scale), and fast (frame rate of 0.8Hz) imaging of living animals.

This work paves the way for biomedical applications ofphotoacoustic and acoustic-optical multimodal imaging based on transparent transducers.

Transparent ultrasonic transducer based on PIN-PMN-PT single crystal for advanced photoacoustic imaging. (a) Photograph and performance of transparent piezoelectric PIN-PMN-PT single crystal; (b) Schematic structure, photograph and performance of developed transparent ultrasonic transducers; (c) High-resolution photoacoustic imaging of vasculature of a mouse ear in vivo; (d) Dynamic photoacoustic imaging of a mouse cortex microvascular structure during an epileptic seizure with a frame rate of 0.8 Hz. (Image by SIAT)

Media Contact: LU Qun

Email: qun.lu@siat.ac.cn

Download the attachment：

Transparent ultrasonic transducers based on relaxor ferroelectric crystals for advanced photoacoustic imaging