Reverse 3D printing to make tiny medical implants
Researchers at RMIT University in Australia have developed a new 3D printing technique that allows them to create incredibly small and complex biomedical implants. The approach is to print glue molds which can then be filled with biomaterial filler. Once the mold dissolves, the structure of the biomaterial remains. Interestingly, the technique uses standard 3D printers, such as those now commonly found in high schools, and PVA glue as the printing material.
Printing tissue replacements is a large area of research, but teams around the world have struggled to create very complex structures that could help improve the viability of printed implants. Tissues are naturally complex, but so far 3D printed biomaterials are somewhat rudimentary in resolution and complexity. These researchers realized that printing an inverted shape might be a better approach to creating more complex structures.
“The shapes you can create with a standard 3D printer are limited by the size of the printing nozzle – the opening has to be large enough to let the material through and ultimately this influences the size you can print,” said Cathal O’Connell, a researcher involved in the study, in an RMIT press release. “But the spaces between printed documents can be much smaller and much more complex. By reversing our thinking, we are essentially drawing the structure we want in the empty space inside our 3D printed mold. This allows us to create tiny and complex microstructures where cells will flourish. ”
The researchers called their printing technique NEST3D (Negative Embodied Sacrificial Template 3D). The printing ink is PVA glue, commonly used by children in craft projects, and the 3D printer used by researchers is of low specification, which they refer to as “ high school. ”
“Above all, our technique is versatile enough to use commercially available medical grade materials,” said O’Connell. “It’s amazing to create such complex shapes using a basic high school 3D printer. It really lowers the bar for entry into the field and brings us significantly closer to transforming tissue engineering into medical reality.
Printed PVA structures can be dissolved away from the core of the biomaterial simply by placing them in water. “The advantage of our advanced injection molding technique is its versatility,” said Stephanie Doyle, another researcher involved in the study. “We can produce dozens of test bioscaffolds in a range of materials – from biodegradable polymers to hydrogels, silicones and ceramics – without the need for rigorous optimization or specialized equipment. We are able to produce 3D structures that can only measure 200 microns in diameter, the width of 4 human hairs, and with a complexity that rivals light-based manufacturing techniques. This could be a massive accelerator for research in biofabrication and tissue engineering. ”
Watch a time-lapse video of the technique:
Study in Advanced materials technologies: Printing between the lines: Complex biomaterial structures fabricated by printing 3D negative embedded sacrificial models (NEST3D)
Going through: RMIT