Hydrogel metapad with ultrasound transparency and broadband focusing for biomedical imaging. - Zhang, Jinhu; Yu, Deshuai; Zhang, Tianye; Gao, Chengtian; Dong, Erqian; Song, Zhongchang; Fan, Chaoyu; Han, Zhehao; Lemoult, Fabrice; Fink, Mathias (National Science Review, 2026)