Controlling the mechanical behavior of dual-material 3D printed meta-materials for patient-specific tissue-mimicking phantoms

Patient-specific tissue-mimicking phantoms are becoming available with the advent of additive manufacturing. Phantoms currently in use are focused on the geometrical accuracy and mechanical properties under small deformation. Mimicking the mechanical properties at large deformation is challenging because of the inherent difference between the mechanical behaviors of polymeric materials and that of human tissues. In this study, the mechanical behavior of soft tissues under a uniaxial tension is mimicked by dual-material 3D printed meta-materials with stiff micro-structured fibers embedded in a soft polymeric matrix. Although the two base materials are strain-softening polymers, some of the designed meta-materials demonstrate certain degree of strain-stiffening behavior. Further investigation shows how the stress-strain curve of the meta-materials can be controlled by the design parameters. Sensitivity analysis is used to study the effects of each parameter. General design guidelines are proposed based on the results of the experiments. Dual-material 3D printed meta-materials have great potential in fabricating patient-specific phantoms with accurate mechanical properties that are associated with the gender, age, ethnicity, and other physiological/pathological characteristics. Mechanically accurate phantoms can play an important role in a variety of biomedical applications, including validation of computational models, testing of medical devices, surgery planning, medical education and training, and doctor-patient interaction. Published by Elsevier Ltd.