A wearable, ultrasonically-actuated magnetic-dipole rotating resonator for mobile communication in cross-medium environment
Zhi Cheng, Xiangyi Wang, Xiangmeng Lv, Jianming Sun, Zhaoqiang Chu, Jing Zhou, Shuxiang Dong
Abstract
Traditional MHz and GHz electromagnetic antennas face challenges of high attenuation rate in cross-medium communication; while mechanical antennas are hindered by their large size, high energy consumption and weak radiation capacity. Here, we report a centimeter-scale, wearable ultrasonically-actuated magnetic-dipole rotating resonator (UA-MDRR) for efficient extremely low frequency (ELF) electromagnetic wave transmission in extreme environments. The UA-MDRR employs a small multilayer piezoelectric ceramic (0.11 cm³) to rotate a disc-type NdFeB magnet, generating ELF radiation through an electro-mechanical-magnetic (EMM) coupling effect. This device achieves a high emission capacity of 24,000 nT/cm³@1 m, outperforming the state-of-the-art resonators/antennas by one to two orders of magnitude. It can emit a magnetic field strength of 2.64 pT in air and 2.12 pT underwater at 100 m, respectively, while consuming only 0.61 W of power. This innovation represents a groundbreaking advancement in cross-medium communication, offering a mobile wearable device for emergency communication in seawater for life saving. A wearable, ultrasonically-actuated magnetic-dipole rotating resonator (UA-MDRR) enables efficient ELF wave transmission in extreme environments. It outperforms traditional antennas with high emission capacity and low power consumption, ideal for emergency communication in seawater.