Nondestructive Evaluation and Detection of Defects in 3D Printed Materials Using the Optical Properties of Gold Nanoparticles

Three-dimensional (3D) printing techniques are being rapidly adopted for prototyping and product development across fields as scientifically diverse as wind energy and regenerative medicine. Through materials processing advancements, the incorporation of nanomaterials within 3D printed parts and structures has begun to enable enhanced material functionalities. In this work, the optical properties of gold nanoparticles are harnessed via the development of functionalized printer filament to detect defects and missing print layers in 3D printed parts. Gold nanoparticles are incorporated within a poly(lactic acid) polymer host matrix, and filament compatible with stock 3D printers is fabricated. Consistent with Beer-Lambert's Law for nanoparticles in solution, a linear relationship between absorbance intensity and the total number of print layers is observed. By analyzing changes in absorbance intensity, the presence, location, and extent of material defects as small as 0.2 mm are identified through a nondestructive approach. The new findings presented here provide key insights and considerations for the development of future nanoparticle/nanomaterial-based, functionalized "smart" materials that can be realized through 3D printing.