A biomimetic anthropomorphic leg phantom for wearable bioimpedance sensing in lymphedema monitoring

This study aims to develop a reproducible, biomimetic, anthropomorphic leg phantom as a controlled platform for the development and evaluation of wearable sensors for low-frequency bioimpedance monitoring of lymphedema. As a proof of concept, a 20-cm multilayer model was developed to establish and characterise the materials and fabrication approach required for future full-scale sensor validation. Electrical and mechanical characterisation of polyvinyl alcohol cryogel (PVA-C) and PVA-based fat and muscle phantoms was performed. The influence of freeze-thaw cycle number and duration on electrical properties and Shore hardness was investigated to support large-scale multilayer fabrication. Muscle anisotropy was reproduced via directional structuring. Reproducibility of electrical properties and long-term stability of PVA-C hydrogels were evaluated under refrigerated, vacuum-sealed storage. A practical methodology for assembling multilayer anthropomorphic leg phantoms was implemented. Electrical properties remained stable across the investigated freeze/thaw conditions, whereas Shore hardness increased with the number of cycles. Two 20-cm-high, three-layer anthropomorphic leg phantoms, representing healthy and stage 2 pathological condition, were fabricated using 3D-printed moulds integrating bone, muscle, and fat. Interfacial bonding between the layers provided mechanical cohesion and electrical continuity. Bioimpedance measurements showed consistent differences between the healthy and lymphedema-mimicking configurations. The methodology enables fabrication and assembly of multilayer anthropomorphic leg phantoms with electrical stability and mechanical cohesion. This proof-of-concept provides a basis for the development of a full-scale anthropomorphic model and its subsequent integration with wearable bioimpedance sensing technologies for lymphedema monitoring.