• heart valve is critical to blood flow
• the efficiency is dictated by the shape, tissue, and biomechanics
• mechanical valves are good but high risk of clots
• tissue engineering looks a a viable replacement to invasive procedures and mechanical heart valves
• start with a type of biodegradable structural material made of fibrin and collagen 
• cells are than put on it to grow a valve
• inkjet, laser, and assisted bioprinting have made it possible to come up with more complex biomaterials
• 3D bioprinting has proven a good way to create 3D structures for things like blood vessels and liver
• hydrogel is in the relatively early stages of design
• it is has been studied in mainly simple structures 
• in hydrogelling a  gridded pattern of tissue is laid down for a support structure for the cells to sit upon
• the proper accuracy must be made of the grid pattern measuring overlap and gaps
• cells are placed on it to grow into the structure that it is laid out to be
• there is a multiple syringe method used to make complex structures
• the proper material is layered on to create the proper form for the tissue