<p>➀ Researchers at DGIST developed ultrasound-based wireless charging for medical implants using a dual-layer piezoelectric harvester; </p><p>➁ The technology achieves over 20% higher energy conversion efficiency and charges commercial batteries in 2 hours within the human body; </p><p>➂ Eliminates risky replacement surgeries and aims for sub-1-hour charging via semiconductor integration.</p>