Comparative Analysis of Exposure Assessment Using Realistic Human Models and Flat Phantoms for Wearable Device at mmWave Frequencies

In contemporary times, wearable devices have proliferated, and their adaptability spans diverse domains, from military to medical settings, with advancements now incorporating high frequencies up to mmWaves (30–300 GHz). This innovation affects human exposure assessment due to changes in penetration depth, resulting in power absorption primarily in superficial tissues, notably the skin. The skin, comprising the stratum corneum (SC) and viable epidermis and dermis layers, is often modeled in multi-layer tissue simulations to quantify exposure parameters. However, existing studies typically use simplified flat phantoms, overlooking anatomical variations typical of an actual human body. This study proposes a novel approach, employing realistic human phantoms from the Virtual Population and a common flat phantom, enriched with SC layer, to compare exposure levels with homogeneous and multi-layer skin models. Simulations using a wearable antenna emitting at 28 GHz reveal consistent underestimation of exposure levels in homogeneous models compared to multi-layer ones, across male, female, and phantom models. Results suggest the SC may act as a shield for inner layers, with discrepancies influenced by anatomical geometry. This study underscores the importance of considering skin structure and anatomical differences in exposure assessments, providing insights for future research, and emphasizing the limitations of simplified flat phantoms in accurately representing human body scenarios.