If you're ever considering printing a blackmail or ransom letter, then you should think twice. Many color laser printers made since the '90s print a special pattern of nearly-invisible yellow dots on every document. Authorities, such as the police, can use those dots to identify the printer that the document came from. The benefit for crime fighting is obvious. The technology was first implemented to help detect counterfeit currency, but it is useful for many other purposes. Thanks to the work of University at Buffalo researchers, your 3D printer is identifiable in a similar manner.
3D printers are not sinister and most people use them for completely innocent purposes. But 3D printers do have the potential for harm in the hands of ne'er-do-wells. 3D-printed firearms have made headlines many times. And authorities may need to track less directly dangerous 3D-printed objects in the future. 3D-printable models are identifiable if they incorporate unique features, but 3D printers themselves haven't been until now.
The University of Buffalo researchers found that FFF (Fused-Filament Fabrication) 3D printers impart a unique signature onto the objects they print. This isn't an intentional feature that the manufacturers implemented, but rather a natural result of the hardware. This is similar to the ballistic identification that law enforcement already performs. According to this research, all FFF 3D-printed objects have unique physical identifiers that they can match to specific 3D printers.
To continue the ballistic metaphor, imagine a 3D printer's hot end as the barrel of a gun and the extruded plastic as a bullet. The thermodynamic properties of a hot end are unique to that specifc hot end, even among hot ends of the same model. Those thermodynamic properties are evident as a signature in the extruded plastic. Lead researcher Zhanpeng Jin says that signature, dubbed a "ThermoTag," is as unique as a human fingerprint.
In testing, the research team examined objects printed by 45 different extruders (including hot end) of the same model. They were able to successfully identify the originating 3D printer with an accuracy of 92 percent. This does require that a database of hardware be available or that investigators have access to the originating 3D printer. But today's ballistic identification works the same way and is very useful. In the future, this research could help authorities locate or prosecute criminals who use 3D printing.