Traditionally, barcodes encode data in a binary format by using groups of parallel lines with varying distance between them. Although a barcode is simple to fabricate, the complexity of the data that can be stored is limited. This research aims to design a method to encode more complex forms of data with higher information densities using 3-d printed magnetic structures. The work presented investigates the basic principles for 3-d magnetic patterning as a means of information storage, tagging, and/or part identification.
In this work, a structure is fabricated using proscribed patterns of magnetic and nonmagnetic regions. These structures are similar to present day barcodes, where the magnetic regions generate an external magnetic field, the stray field, that can be interrogated with a Hall effect or similar magnetic probe. The regions of magnetic and nonmagnetic field can be spaced apart at varying distance, or the thickness of each region can be varied, both of which affect the resolution of the magnetic signature of the stray field generated by the pattern. The patterns yield a magnetic equivalent to the binary optical nature of bar codes. However, unlike with the fabrication of barcodes, other processing variables influencing the stray field of the structure can be altered to add complexity to the data encoding. For example, by using hard magnetic powders such as barium hexaferrite, which consists of magnetically anisotropic plate-like particles, the magnetic regions can be oriented in arbitrary directions yielding more intricate stray fields, and consequently more complex magnetic signatures and higher information density.
This work first provides a proof of concept using neodymium magnetics inserted into a 3-d printed patterned structure to produce the stray field, which is characterized using a gaussmeter. The creation of this structure is the simplest proof of concept of a magnetic bar code. A second proof of concept 3-d prints both the nonmagnetic and magnetic parts of the structure using Protopasta magnetic filament (consisting of PLA with 45 wt.% iron particles) and standard ABS filament in a dual material FDM printer. Printing alternating regions of magnetic and nonmagnetic material form the now passive magnetic structure. A force gauge with a magnetic tip is used to determine the signature of the stray field resulting from the magnetic pattern. Finally, a computational model is developed to simulate stray field and resulting signature of the printed magnetic structures for comparison with experiments.
Future work includes using magnetic filament consisting of hard magnetic particles such as barium hexaferrite, whose magnetic anisotropy facilitates complex magnetic alignments within the magnetic regions of the printed structure. Complex alignments allow increasingly sophisticated magnetic signatures, permitting an increase in the complexity of stored data, as well as an increase in information density.