Tissue phantoms to mimic the dielectric properties of human forearm section for multi-frequency bioimpedance analysis at low frequencies.

Phantoms, or physical simulants of biological specimens are useful for research and development due to the unavailability of real tissues. One such example is human blood, which is a precious resource in healthcare and is not normally available for research purposes, unless it is no longer fit for human use. This work focusses on the considerations for developing a human forearm phantom specifically to exhibit the dielectric properties of fat, muscle and blood tissue domains, for bioimpedance analysis. The behavior for the tissue simulants were identified based on the conductivity and permittivity values within the β dispersion frequency range (1 kHz-2 MHz). A mixture of 80% propylene glycol and 20% 4 M saline solution was found to replicate the properties of blood within acceptable tolerances in the β dispersion frequency range. A 5% agar with 0.05% saline mixture was found to mimic the properties of fat, whereas the muscle properties were mimicked through a suspension of agar, gelatine, saline and propylene glycol. This was followed by construction of the forearm phantom with three geometries to simulate the three arterial diameter instances due to blood flow. The measurements were performed using the Quadra® Impedance Spectroscopy device within 1 kHz-349 kHz which were fitted to a Cole model to estimate the entire frequency spectrum within 1 kHz-2 MHz and compared with a previously performed simulation study. This methodology can provide a very economical, reproducible and robust means for investigating the dielectric response of tissues across several research and training platforms, and more importantly bioimpedance applications.