Liver is the largest gland in human body. It is also the largest (internal) organ in our body and can weigh up to 1.5-1.6 kg for a human adult. That is, about 1/50th of the body weight is because of liver. The liver carries out a multitude of functions in our body (as many as 500) and it is impossible to replicate these many functions in a single natural or artificial organ or machine. Some of the critical functions of liver include secretion of bile juices for decomposition of lipids & vitamins, preparation of proteins for blood plasma that enables blood clotting and also detoxification. Patients suffering from liver failure use liver dialysis equipment to mimic some of the features of liver.
Hope this helps.