3D-printed thermoplastic polyurethane for wearable breast hyperthermia

Abstract

Microwave breast hyperthermia is a class of cancer treatment, where breast temperature is elevated by a focused electromagnetic (EM) radiation to impair cancer cells. While the current mainstream in microwave breast hyperthermia is centered on bulky and rigid systems, wearable antennas would offer considerable benefits such as superior conformity to individual patient anatomy and better comfort. In this proposition, this paper presents 3D-printed flexible antenna prototypes for wearable breast hyperthermia applications. Since the dielectric properties are expected to dominate the antenna gain but could be influenced by the solid volume percentage, this work first investigates the relationship between the dielectric properties and solid volume percentage of a 3D-printed flexible filament. From this, it is found that with decrease in the solid volume percentage, the dielectric constant decreases following the classic theory of dielectric mixture. Based on this observation, optimal antennas are designed for substrates in different infill levels by running a 3D full-wave EM simulator and fabricated by 3D printing a polyurethane filament. Temperature elevations in a synthetic breast tissue are measured by a thermometer and are ~ 5.5 °C and ~ 3.2 °C at the 5 mm- and 7 mm-deep locations, respectively. The infill percentage makes little difference in the heating efficacy. Based on these findings, this translational study sheds light on the possibility of wearable breast hyperthermia with the 3D-printed flexible and conformal antennas.