Biological 3D printing technology, especially in vivo printing of cells, tissues and organs, has attracted extensive attention in medicine, biology and engineering. Biological 3D printing is a regenerative medical engineering technology based on the principle of “additive manufacturing”, which takes the special biological “printer” as the means, processes active materials including cells, growth factors and biomaterials as the main content, and aims at reconstructing human tissues and organs. It represents one of the highest levels of 3D printing technology. < / P > < p > it is understood that in biological 3D printing technology, researchers often use ink-jet printing technology, which can quickly and accurately print small ink drops to the corresponding position. The working principle of inkjet printer is: there is a heating element in the nozzle, which can quickly heat the water in the ink cartridge to 200 ℃, and the water can spray out the ink drops in the process of gasification. The researchers put the cell suspension into a special ink cartridge, and they could print the cell successfully. And the printing process only takes about 20 microseconds. Before the heat can be transferred to the ink droplets, the ink droplets have been ejected, so the high temperature does not kill the cells. < / P > < p > in addition, inkjet printers can print out different cells. For example, printing a structure similar to a blood vessel can print endothelial cells to the inner layer of the tube wall and smooth muscle cells to the outer layer of the tube wall. By printing layer by layer, a product similar to the normal structure can be obtained.