| The rapid development of biofabrication technology has brought good news to the regeneration of human organs and tissues.This technology uses biomaterials to create organs or tissues.Biofabrication is divided into extrusion printing and inkjet printing mainly.Limited by the structure and materials used in the extrusion printing equipments,the material is prone to wire breakage and cell damage,while piezoelectric inkjet printing can solve the above problems.Inkjet printing uses liquid materials mostly,which causes less damage to cells.The aim of this paper is to explore temperature sensitive materials suitable for inkjet printing and to analyze its rheological and temperature sensitive properties.Combined with the working principle of printed head,we analyzed the micro-jet process.We designed a temperature control platform suitable for inkjet printing,and analyzed the influence of its internal temperature field on the bonding process of inkjet printing based on the temperature sensitive characteristics.We used inkjet printing to complete the manufacture of human blood vessels containing vascular smooth muscle cells(Smooth Muscle Cell,SMC cells),and carried out biological evaluation.Firstly,for structures of ink-jet printing equipments,we choosed Gelatin and GelMA bio-materials,and explained its material preparation process.We selected SMC cells for culture and propagation,and dissolved them into GelMA sol for culture,and analyzed the biological characteristics of GelMA materials containing SMC cells.Whereafter we used rheometer equipments to analyze the distribution of viscosity and temperature.Based on the working principle of the piezoelectric ceramics inside the nozzle,we determined the variables influencing the injection effect of droplets.By means of simulation analysis and experimental research,we explored the basic law of micro-injection of printed head.Based on the experimental equipments,we established an ink-jet biological 3D printing micro-injection system.Secondly,based on the temperature sensitivity,we analyzed the gelation principle of the Gelatin & GelMA materials.By using the inverted tube method,syringe method and viscoelastic method,we analyzed the distribution relationship between the energy storage modulus and loss modulus of the material and the temperature,and determined the gel temperatures of the Gelatin & GelMA materials.Based on the temperature sensitive characteristics of the materials,we adopted simulation analysis and infrared optical imaging experimental methods.Based on the relationship between the internal air temperatures and the bottom cover temperatures,the temperature control room was designed and developed,which was suitable for Gelatin & GelMA to gel.Based on Gelatin & GelMA gel temperatures,we made the high temperature of liquid into the low temperature gel state,by controlling the internal temperature distribution,which realized the physical crosslinking of the spray droplets.Finally,based on the micro-injection principle,the applied voltage and pulse width were adjusted to change the working time and shape of the piezoelectric ceramics.Based on high-speed camera observation,we analyzed the effects of equipment parameters including voltage,pulse width,air pressure and temperature on droplet generation.We used Gelatin sol without cells to bio-3D printing test,and explored a suitable printing parameters.Using GelMA sol containing SMC cells,we successfully produced the human vascular structure containing the cells.By means of cell culture,cell staining and fluorescence microscope observation,we had realized the biological evaluation of human vascular structure.The average cell survival rate was 93.25%. |
PDF Full Text Request