Enhanced head phantom for wearable microwave tomography devices evaluation

In this article, an inhomogeneous multi-layer semi-solid human head phantom introduces to use in the validation of wearable microwave tomography (WMWT) devices. The intracranial tissues (gray matter [GM], white matter [WM], dura, cerebrospinal fluid [CSF], cerebellum, spinal cord), and skin were mimicked using semi-solid artificial tissue emulating (ATE) materials. The electrical properties of mimicked tissues are measured and compared with real human head tissues at 0.5-4.5 GHz spectrum. The novelty of the proposed phantom is the presence of the skin layer with a high dielectric constant and a realistic skull layer in terms of electrical and anatomical properties. These layers have a critical role in on-body antenna performance and make the proposed phantom a useful tool for the evaluation of WMWT devices, as well as microwave tomography ones. The phantom was simulated and fabricated as an eight-layer model. For evaluation, a comparison was made between the simulated and measured reflection coefficients of a reference on-body antenna located at the numerical model and fabricated phantom, respectively. The results suggest that the head proposed phantom can be considered an effective tool for WMWT instruments.