Microassembly fabrication of tissue engineering scaffolds with customized design

This paper presents a novel technique to fabricate scaffold/cell constructs for tissue engineering by robotic assembly of microscopic building blocks (of volume 0.5 x 0.5 x 0.2 mm(3) and 60 mu m thickness). In this way, it becomes possible to build scaffolds with freedom in the design of architecture, surface morphology, and chemistry. Biocompatible microparts with complex 3-D shapes were first designed and mass produced using MEMS techniques. Semi-automatic assembly was then realized using a robotic workstation with four degrees of freedom integrating a dedicated microgripper and two optical microscopes. Coarse movement of the gripper is determined by pattern matching in the microscopes images, while the operator controls fine positioning and accurate insertion of the microparts. Successful microassembly was demonstrated using SU-8 and acrylic resin microparts. Taking advantage of parts distortion and adhesion forces, which dominate at micro-level, the parts cleave together after assembly. In contrast to many current scaffold fabrication techniques, no heat, pressure, electrical effect, or toxic chemical reaction is involved, a critical condition for creating scaffolds with biological agents. Note to Practioners - Tissue engineering aims at generation of artificial tissues and organs using patient specific cells. Cells obtained from an individual are cultured and seeded onto a 3-D scaffold that will slowly degrade and resorb as the bone structures grow and assimilate in vivo. This paper develops a novel robotics technique to fabricate scaffolds with custom properties, which could provide optimal growth conditions. Our technique, consisting of assembling microscopic building blocks, can potentially provide physicians the freedom to design and modify the scaffold surface morphology and topology at the micron level in order to facilitate cellular colonization and organization.