More than 500,000 people paid $24 each to jostle with each other for unbelievable views of anatomical bodies and parts at a show called BodyWorlds2 at the Boston Museum of Science. Human cadavers were displayed in various poses with sinews, bones and organs all fully shown. The figures, called Plastinates, have been on tour in the USA for two years at science centers in Chicago, Cleveland, Los Angeles and Denver, Boston, St. Paul and Houston. I only saw about 60% of the exhibit in Bostonâ€”I didnâ€™t have the patience or the stamina to wait in all the lines, or fend off all the elbows.
Not surprisingly, there is a fabulous materials story behind the plastinates. A German anatomist named Gunther von Hagens invented a technology to preserve specimens for medical observation using solvents and reactive polymers. The process goes like this: 1) Body parts (sometimes an entire body) are placed in a bath of ice-cold acetone. The solvent replaces body fluids in a process called freeze substitution, 2) The specimen is dehydrated, 3) The part goes into another solvent bath for defatting 4) The part then placed into a polymer solution, which is brought to a boil in a vacuum. Solvent is continuously extracted from the specimen. As the solvent leaves the specimen, polymer is drawn into the tissue as a replacement. 5) After the â€œforced impregnationâ€� is completed, the specimen is cured with light, gas or heat, depending on the type of polymer.
Picking the right polymer is one of tricks of the process. The polymers must be reactive, have low viscosity, resist yellowing, and must be compatible with human tissue. Commonly used are silicones, epoxies, and polyester copolymers. Many auxiliary materials are also listed for sale at http://www.biodur.de/.
It should also come as no surprise that there are plenty of ethical issues surrounding these exhibits. Where did all of the bodies and parts come from? An investigation by National Public Radio was less than satisfied with claims that all specimens came from people who donated them for that purpose. A competing exhibition uses body parts from unclaimed Chinese. There was significant opposition to the exhibition when it first opened in Germany because of laws requiring the burial of all corpses.