The specific domain of this content is Advanced Additive Manufacturing and Biomedical Visualization, utilizing medical imaging data (Micro-CT/DICOM) for high-fidelity, multi-material 3D printing.
Expert Persona Adopted: Senior Additive Manufacturing Engineer & Biomedical Modeler.
Abstract:
This presentation details the end-to-end workflow for creating a high-resolution, multi-material anatomical model using Stratasys PolyJet technology, specifically the J5 MediJet system. The project goal is to transform Micro-CT scan data of a mosquito head, initially in DICOM format, into a highly magnified, visually transparent physical model for exhibition purposes.
The process involves initial segmentation of anatomical structures (skull, brain, trunk) and subsequent preparation within the Cb-cut print slicer. Critical parameters include scaling the model to the size of a human skull, assigning specific colors (vivid hex codes for the brain) and material properties, most notably utilizing clear resin for the external shell to allow visualization of internal organs. The PolyJet printer, characterized by its spinning build plate, picoliter droplet deposition, and 16-micron layer height, required a significant 63-hour printing cycle due to the 100% infill required for optically clear parts. Material estimation highlighted the consumption of 2.5 kg of clear resin. Post-processing focuses on removing wax-like support material and subsequent polishing to achieve optimal surface clarity. The final output is a detailed, geometrically accurate exhibit demonstrating the capabilities of high-end additive manufacturing in scientific visualization.
Summarization of Transcript
0:01 Introduction to PolyJet Technology: The focus is on multi-material PolyJet 3D printing, a highly expensive technology generally inaccessible to hobbyists, demonstrated via an exhibition project.
0:42 Data Source and Goal: The model is derived from a Micro-CT scan of a mosquito head, comprising approximately 2,000 DICOM (Digital Imaging and Communication in Medicine) slices. The objective is to segment and print the structures (brain, trunk, head) with a transparent skull for internal visualization.
1:22 Data Processing: The raw DICOM data is processed using segmentation software to convert pixels into voxels (volumetric pixels), isolating the target anatomical structures.
2:28 Slicing and Scaling: The model is imported into the Cb-cut print slicer, native to the machine manufacturer. The mosquito head is scaled substantially to roughly the size of a human skull for maximum visibility during the exhibition.
2:55 Material Assignment: Colors and materials are applied: the outer shell is designated a "see-through" (clear) material, while the brain and trunk are assigned opaque, vivid colors (specific hex codes used for the brain).
3:39 Material Estimation: The slicing process estimates significant material consumption: 2.5 kg of clear material, 800 ml of white, 300 ml total of CMY pigments, and 1.1 kg of support material.
4:09 Operational Context: The printing is conducted at the Point-of-Care Manufacturing Lab at the University Hospital in Basel, which utilizes industrial 3D printing for patient care applications (founded by Prof. Dr. Florian Thieringer).
5:01 Hardware Specifications (J5 MediJet): The printer is identified as a Stratasys J5 MediJet, designed for medical applications. It features a unique rotating printing bed, eliminating linear movement of the component being printed.
5:35 Printing Mechanism Precision: Material is deposited via hundreds of tiny nozzles that dispense material in picoliter-sized droplets (very tiny amounts) using piezoelectric crystals to open and close individual valves.
6:07 Layer Resolution and Curing: The layer height is extremely fine, specified at 0.016 mm (16 microns). Deposition is immediately followed by a roller for flattening and a UV lamp for photopolymer curing.
7:22 Multi-Material Capability and Cost: The machine mixes five base materials on-the-fly to achieve diverse colors and mechanical properties (e.g., hard, soft, rubber-like). Material is expensive, costing 400β700 Swiss Francs per canister (~700 CHF per liter).
8:35 Print Time: The total print duration is estimated at 63 hours and 29 minutes. This long duration is attributed to the necessity of 100% infill required for the optically clear component.
9:09 Material Refill Requirement: Despite pre-filling, the machine software indicated that the clear material would deplete after two days, requiring an interruption for a material change during the print.
10:01 Post-Processing: After the 63-hour print, the part features smooth surfaces where no support was present, and a matte finish on areas contacted by the support material.
10:25 Support Removal: The support material (described as wax-like) is removed manually in large sections, followed by water blasting to clean the small residues.
11:38 Final Visualization: Applying water demonstrates the full transparency of the outer shell, clearly revealing the internal brain (triangular structure) and the blue trunk feeding through the head. Remaining layer lines are expected to be removed via polishing.
13:03 Teaser on Nano-Printing: The video concludes with a brief mention of specialized nano-printing technologies, specifically two-photon polymerization ("Nanostripe technology"), capable of printing fifty gears (3mm diameter) on a glass plate that are invisible to the naked eye.