Biocompatibility and mechanical behaviour of three-dimensional scaffolds for biomedical devices: process–structure–property paradigm

Abstract

We elucidate here process-structure-property relationships in implantable biomaterials processed by rapid prototyping approaches that are based on the principle of additive manufacturing. The conventional methods of fabrication of biomedical devices including freeze casting and sintering are limited because of difficulties in adaptation at the host site and mismatch in micro/ macrostructure, mechanical and physical properties with the host tissue. Moreover, additive manufacturing has the advantage of fabricating patient-specific designs, which can be obtained from the computed tomography scan of the defect site. The discussion here comprises two partsthe first part briefly describes the evolution and underlying reasons that have led to 3D printing of scaffolds for tissue regeneration. The second part focuses on biocompatibility and mechanical properties of 3D scaffolds, fabricated by different approaches. The article concludes with a discussion on functionally graded scaffolds and vascularisation of 3D porous scaffolds that are envisaged to meet the requirements of the biomedical industry. In general, the mechanical properties of 3D printed scaffolds are governed by pore architecture, pore volume and percentage porosity. To ensure long-term endurance and the ability to withstand abrupt impact, it is important that the fabricated materials have a good combination of strength and energy absorption capability. While scaffolds with high interconnected porosity are preferred for tissue regeneration, such structures lack adequate mechanical strength and energy absorption capability. These mutually opposing requirements of high porosity and mechanical strength in conjunction with high energy absorption have hindered the application of 3D scaffolds as biomedical devices. In this regard, functionally graded 3D structures with high strength and energy absorption are potentially attractive for biomedical devices.

Mechanical Properties and In Vitro Behavior of Additively Manufactured and Functionally Graded Ti6Al4V Porous Scaffolds

“…The stiffness of the tested scaffolds varied in the range of 1.6 to 9.0 GPa, which aligns with the stiffness range of the trabecular (0.4 GPa [59,60]) and cortical bones (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)24]). The yield stress values of the scaffolds were in the range of 53 to 392 MPa, which lies in the range of cortical bones MPa [24,61]), but it is not suitable for a replacement of trabecular bone, 2-17 MPa [60].…”

Advancements in three-dimensional titanium alloy mesh scaffolds fabricated by electron beam melting for biomedical devices: mechanical and biological aspects

“…In additive manufacturing, the properties of the fabricated component are governed by the unit cell, while the design is dictated by the resolution offered by the additive manufacturing process/equipment [1]. For ARCAM A1 the resolution is ±0.4 mm based on the information in the user's manual.…”

“…Additive manufacturing is a rapid prototype (RP) technique involving layer-by-layer processing of three-dimensional (3D) complex structures as directed by the computer-aided design (CAD) [1,2]. Additive manufacturing can be utilized to fabricate complex structures of relevance to aerospace and patient-specific implants.…”

Discrete Optimization of Internal Part Structure via SLM Unit Structure-Performance Database

“…The results showed good consistency of the theories with the experiments when structural symmetry is maximized. Kumar et al [13] studied the effects of the foam structures with different pore units and porosity on the performance of the scaffolds used in human tissue regeneration. The mechanical properties were tested.…”