3D Printing Auxetic Architectures for Hypertrophic Scar Therapy

Fitting the human body for different purposes such as flexible electronics and functional garments can be a challenging task. Pressure garments are used to treat hypertrophic scars (HSs)pr. However, they have often failed to provide consistent pressure during joint movement. To increase the therapy efficacy, the application is proposed of 3D printed thermoplastic polyurethane (TPU) with an auxetic architecture insert for pressure therapy. Auxetic material can undergo an out-of-plane bending into a synclastic curvature, which can easily accommodate the contours of the human body. In this study, the synclastic effect of the auxetic structure under out-of-plane bending is illustrated through finite element analysis (FEA) first. Next, the formability, structural deformation, and auxetic response of re-entrant (RE) and double-arrowhead (DAH) auxetic structures when loading by a spherical surface in out-of-plane direction are unprecedentedly evaluated experimentally and numerically. It can be observed the internal angle of auxetic structure plays an important role regarding shape formability. Nevertheless, the result of wear trial reveals this design facilitates a stable level of pressure during the body motion which promotes the recovery of HS. It is believed the characterized result of auxetic architectures not only contribute to HS therapy, but also any type of biomedical devices.