Automation Of Batched Spatial Manipulation And Assembly Of Cells Through Dielectrophoresis

Tissue engineering(TE)is an interdisciplinary research aimed at repairing and regenerating tissues and organs by transplanting artificial tissues fabricated outside the human body.Tissue construction commonly involves harvesting stem cells from bone marrows of patients and their subsequent culturing on biomaterials as scaffolds to facilitate tissue development.However,many of proposed scaffolds exhibit relatively simple intrinsic designs with limited control of cell distribution.In this thesis,novel scaffolds are designed for automatic seeding of biological cells through dielectrophoresis(DEP)for TE.This thesis is performed based on the following three perspectives.First,a novel scaffold structure constituting multiple layers of biocompatible materials is proposed to incorporate DEP technique to manipulate and to pattern biological cells in 3D domains.Different processing parameters are examined to determine their influence on quality and viability of 3D cellular patterns.Experimental results show that the designed scaffold and its automated DEP-based patterning mechanism can be used to construct artificial tissues for TE applications.Second,scaffold with honeycomb-like pores is designed to mimic geometries of native bone tissues for tissue regeneration.Cells on scaffold are automatically patterned into multiple layers of honeycomb patterns.Three different types of mammalian cells are considered,and experiments are conducted to identify different factors affecting formation of honeycomb patterns.Viability tests are conducted to examine biocompatibility of material and cell death associated with DEP.Third,this thesis proposes a new method to integrate active cell seeding mechanism with 3D printed scaffolds through DEP.This scaffold adopts a concentric-ring design similar to that of native bone tissues.The scaffold can be fabricated with commercial 3D printers.Polylactic acid is selected as printer material,and fabricated scaffold is coated with gold to enhance conductivity for DEP manipulation.COMSOL-based simulation study confirms that non-uniform electric fields can be successfully generated under a voltage input.Properties of 3D-printed scaffold are characterized through a series of experiments.In summary,this study well demonstrates that the proposed scaffolds and their automated DEP-based patterning mechanism can be well utilized to construct artificial tissues for TE applications.Multilayer scaffold structure incorporates DEP for automatic manipulation of cells to form 3D patterns.Development of honeycomb-like scaffold enhances cell seeding for high-quality artificial bone tissues.Development of this new type of 3D-printed scaffold offers a new and rapid way of fabricating engineered scaffolds,which can arrange cells into different patterns.This thesis will help promote applications of DEP mechanism in development of artificial tissues.