SANE: Safe Charging with Wave Interference

With wireless power transfer becoming a popular technology for recharging devices in various fields, the accompanying potential threats of electromagnetic radiation (EMR) have attracted widespread attention from researchers. Although some state-of-the-art safe charging solutions have been developed to address EMR threats, they all ignore wave interference, resulting in a gap between their theoretical models and real-world applications. In this work, we focus on developing a safe charging scheme considering wave interference, termed Safe chArging with wave iNterferencE (SANE), aiming to maximize the overall charging utility while ensuring the EMR safety of critical locations. Specifically, we first build a charging model with wave interference to explore the impact of wave interference on the EMR intensity. Then, we devise a charger placement method that meets safe charging requirements while enabling devices to harvest maximum power from constructive interference. Finally, we conduct extensive simulations and field experiments to evaluate the effectiveness of SANE scheme. The results demonstrate that SANE not only ensures the EMR intensity at all critical locations remains below the safety threshold but also outperforms the comparison algorithms by an average of 89.65% in overall charging utility.