‘Fingerprint’ for 3D printer could help protect intellectual property

3D printing is transforming everything from fashion and health care to transportation and toys. But this rapidly evolving technology, also known as additive manufacturing, can threaten national security and intellectual property rights.

To reduce the illicit use of 3D printers, Zhanpeng Jin, an associate professor in the Department of Computer Science and Engineering at the University at Buffalo, is developing a way to track the origin of 3D-printed items.

Jin’s concern was that, as long as people have the digital design for an item – which can be downloaded from the internet, sometimes as open-source material – they can print out anything they want, ranging from computer parts and toys to more dangerous objects such as fully functional handguns and assault rifles.

“So, what would be the best way to protect our intellectual property from someone else printing the same design using their own printer?” Jin asked. “We wanted to find something internal. What would be the inherent signatures printed by my own 3D printer instead of another 3D printer?”

3D printers build three-dimensional objects by adding successive layers of printing materials according to the digital design for a 3D model. Each 3D printer has an ‘extruder,’ which pushes the building material along. The extruder’s hot end then melts the material and places it on the print bed to build the model.

The researchers focused on this component as part of their study. This is because each extruder’s hot end has its own unique heating properties, which impact the precise construction of the 3D model. Such thermodynamic properties can identify the specific extruder and, thus, the model of a 3D printer, as unique as a human fingerprint, or what Jin has called a ‘ThermoTag’.

For the study, Jin compared the process to using a laptop to write a letter. Because software exists that can track keystrokes, an observer can see every step that went into the letter, including the writer’s unique writing style.

Similarly, because of the unique properties of each 3D printer’s extruder, a researcher can examine the specific manner in which a user has made a 3D-printed object, and compare that to a database of various extruders until they make a match. From there, once they identified the model printer, authorities could track down the purchaser of the said model if they had, for instance, used the printer to build an illegal assault rifle.

Jin and his team found that, by examining and comparing the ThermoTag features of 45 different extruders of the same model, they could identify the source printer with an accuracy rate of 92 per cent.

“This ThermoTag will behave like the fingerprint of the 3D printer. When you print out a new product, you can use watermarking,” Jin said, noting that they can use the watermark to invisibly embed such information as the printer’s manufacturer, label and serial number in the product. “So that would make this watermark of this product unique.”

According to Jin, it’s possible that someone could replace their extruder to try to avoid detection. “That’s why it’s important to create a database of these parts for comparison,” he said.