Direct visualization and three-dimensional reconstruction of structures formed by electrophotographic toner

• We have imaged in three dimensions a particle sediment using Confocal Laser Scanning Microscopy.
• We can determine the three dimensional positions and the size for each particle.
• The microstructure we measured is consistent with what predicted for highly cohesive particles.
• The method may be used to determine parameters such as packing fractions and coordination numbers.

Materials or objects fabricated with solid particles, such as in additive manufacturing, can assume interior structures influenced by the arrangement of the particles. These structures will result in various porosities and directly impact the performance of the products constructed. It is difficult to image and visualize particle structures from dense powder samples.We have determined particle positions in three-dimensions within toner powders. With these particle positions, a visualization of the particle structure can be reconstructed. The determination of particle positions involves imaging with a confocal laser scanning microscope to capture a stack of cross-sectional images of florescent particles and analyzing the resulting images. The feasibility of imaging sedimented particulate samples by using micron-sized poly-dispersed electrophotographic printing particles has been demonstrated. The XYZ co-ordinates and radii for these particles (which are assumed to be spherical) have been calculated in several selected sampling volumes. Consequently, a size distribution for the particles has also been obtained. The three-dimensional reconstruction of these particles illustrates a highly porous structure. This methodology of three-dimensional particle mapping and visualization can potentially lead to much needed materials and structural analyses for fine particles.

The reconstruction of the three-dimensional microstructure formed by electrophotographic toner has been created by using positions determined from confocal laser scanning microscopy. The “suspended” particles are in actual contacts with and being supported by particles in neighboring cells. The openness of the structure reflects the low porosity and the highly cohesive nature of the toner.Figure optionsDownload as PowerPoint slide