A Self-adaptive ultrasound patch for transcranial multimodal dynamic focusing

Ultrasound offers a valuable potential technology solution for continuous focused stimulation in brain science due to its non-invasive, deep penetration, and precise focusing ability. However, existing wearable focused ultrasound requires a trade-off between rigid devices that cannot conform to complex surfaces and flexible probes that have difficulty achieving dynamic focusing. This paper presents a curvature-adaptive and reconfigurable focusing (RF) flexible transducer (CR-FFT) capable of multi-scale beamforming. Laser processing of submillimeter-scale flexible stretchable substrate enables CR-FFT to fit various complex surfaces. This 64-element matrix probe has a row-column addressing (RCA) structure, high flexibility (sphere radius R ≥ 1.5 cm), lightweight (weight ≤ 1.58 g), and miniaturization (size ≤ 9 mm²) meet the needs of wearable devices. Its mechanical, electrical, and acoustic properties were systematically characterized, and RCA beamforming was validated under multiple activation modes. In addition, we achieved non-invasive phase compensation on a sheep skull complex surface, which verifies the potential of CR-FFT in wearable imaging and focused therapeutic applications such as non-invasive neuromodulation.