KNN-based frequency-adjustable ferroelectric heterojunction and biomedical applications
Tao Zhang, Haoyuan Hu, Hong Jiang, Zhen Wang, Jinfeng Lin, Ye Cheng, Guo Wei, Di Ke, Hang Hai, Mengshu Ta, Jun Ouyang, Jiwei Zhai, Xiaofei Yang, Songyun Wang, Benpeng Zhu
Abstract
Abstract High-performance lead-free K 0.5 Na 0.5 NbO 3 piezoelectric ceramics present a practical alternative to lead-containing counterparts by effectively reducing potential environmental hazards. This advancement is particularly relevant to the development of ferroelectric heterojunction devices for biomedical applications. Here, we design and fabricate a frequency-adjustable ferroelectric heterojunction based on the developed K 0.5 Na 0.5 NbO 3 piezoelectric ceramics with a high piezoelectric coefficient ( d 33 = 680 pC/N). By leveraging flexible encapsulation, the heterojunction achieves miniaturization ( φ = 13.3 mm, h = 2.28 mm) and suitability for implantation. After penetrating the rat skull, the ultrasound generated by the heterojunction at a frequency of 3 MHz reaches a focal depth of about 7.9 mm, a focal width of approximately 480 μm at −6 dB, and millimeter-scale continuous focal tuning (1.5 mm) within a narrow frequency range (2.7–3.3 MHz). Additionally, the implanted heterojunction enables long-term and high-precision transcranial neuromodulation, and consequently yields therapeutic effects in a myocardial infarction animal model. Collectively, this study highlights a viable strategy for developing and applying lead-free ferroelectric heterojunctions, expanding their potential in brain modulation, and providing new insights into clinical treatments of myocardial infarction.