Georgia Tech and Rutgers University engineers have devised a three-layer security system to prevent Additive Manufacturing (AM) from being compromised.
3D printing has been replacing conventional fabrication processes in critical areas ranging from aerospace components to medical implants. But because the process still relies on software to control the 3D printer, AM could be easily hacked, or compromised by unscrupulous operators who want to cut corners.
Not anymore: The Georgia Tech, Rutgers system uses acoustic and other physical techniques to confirm that the printer is operating as expected, and nondestructive inspection techniques to verify the correct location of tiny gold nanorods buried in the parts.
The researchers assert that the validation technique is independent of printer firmware and software in the controlling computer.
The three components of the new system include:
- Acoustic measurement of the 3-D printer in operation. When compared to a reference recording of a correct print, this acoustic monitoring – done with an inexpensive microphone and filtering software – can detect changes in the printer’s sound that may indicate installation of malicious software.
- Physical tracking of printer components. To create the desired object, the printer’s extruder and other components should follow a consistent mechanical path that can be observed with inexpensive sensors. Variations from the expected path could indicate an attack.
- Detection of nanorods in finished components. Using Raman Spectroscopy and computed tomography (CT), the researchers were able to detect the location of gold nanorods that had been mixed with the filament material used in the 3-D printer. Variations from the expected location of those particles could indicate a quality problem with the component. The variations could result from malicious activity, or from efforts to conserve printer materials.
The researchers tested their technique on three different types of 3D printers and a computer numerical control (CNC) machine using a polyethylene tibial knee prosthesis as a test case. The gold contrast materials were tested to make sure they wouldn’t compromise the structural integrity of the printed components.
Apart from detecting malicious activity or quality problems, the technique could also be used to stop inadvertent production problems, and help reduce material waste.
Image and excerpts: Christopher Moore/Georgia Tech