Echo‐vision: A Dual‐Function Ultrasonic Platform for Acoustic Energy Harvesting and Varifocal Echo Imaging. - Lin, Zi‐Bin; Liu, Ji‐Zhen; Hu, Yu; Li, Zong‐Lin; Li, Peng‐Qi; Peng, Yu‐Gui; Li, Bin; Zhu, Xue‐Feng (Advanced Energy Materials, 2026)