Eco-Friendly Bioimpedance Muscle Phantom: PVA-Agar Hydrogel Mimicking Living Tissue at Low Frequencies

In this study, we present the development of a muscle phantom using a hydrogel composed of polyvinyl alcohol (PVA), agar, graphite, and NaCl, cross-linked through freeze/thaw cycling. We compared the properties of the PVA hydrogel with those of a PVA-agar hydrogel filled with graphite and NaCl. To characterize and optimize the mixtures, samples with varying graphite concentrations were prepared, and their electrical properties were measured using bioelectrical impedance spectroscopy (BIS) over a low-frequency range (1 kHz-1 MHz). Two types of studies were carried out: one using 2-electrode standard measuring cells for comparison with literature data, and another using 4-electrode measurement on an anthropomorphic phantom, developed using a 3D-printed mould in the shape of a leg. The mechanical properties of the hydrogel seemed to be very similar to those of living muscle. BIS measurements on the anthropomorphic leg displayed an expected Cole's behaviour, indicating its potential to mimic the electrical properties of living muscle.