Multi-material 3D printing advances personalized medicine

Imagine this: A pharmaceutical “factory” about the size of a quarter sits next to a hospital bed. Micrometer-size wires and channels mix various drugs—painkillers, blood thinners and antibiotics—in combinations that match a patient’s evolving condition. That doesn’t exist . . . yet. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden, Germany, are developing technologies that may, one day, make it a reality. First and foremost, they have introduced an additive manufacturing (aka 3D printing) process that can build medical devices from multiple materials—combinations of plastic, glass, ceramics and metal—simultaneously.

The researchers are focusing on suspension-based additive manufacturing methods in combination with other techniques to create not only micro reactors—the bedside drug dispenser is an aspirational example—but also bone implants, dentures and surgical tools. The technique would allow the fabrication of medical components with limitless design freedom, says team leader Dr. Tassilo Moritz of Fraunhofer IKTS’s Materials and Processes business division. “We have no limitations in terms of type or color of material for the target components. This allows us to process ceramics, glass, plastic or even metal using thermoplastic 3D printing. One more advantage is that several different materials can be processed at the same time,” adds Moritz. The scientists have successfully made components out of high-performance ceramics and hard metals in the lab, and they are now looking for partners to develop real-world applications.

A press release on the IKTS website describes the process and explains the key role of optimizing the ceramic or metallic suspensions. The mixtures rely on a thermoplastic binder that becomes liquid at temperatures of around 80° C. This is a crucial step in additive manufacturing, explain the researchers, because it means the suspensions can quickly cool down, allowing one layer after another to be deposited in sequence. Powder particles of metal, glass or ceramics are dispersed in the binder. 

After deposition, the droplets immediately harden as a result of the quick cooling process. The workpiece is then built up point by point on a flat platform, allowing different materials to be deposited at the same time via multiple application units.

“Another challenge is adjusting the behavior of the different suspensions during the subsequent sintering of the components, to prevent any defects,” says Moritz. “To this end, we modify the initial powder through special grinding processes.” In sintering, finely grained ceramic or metallic substances are heated under pressure. The temperatures of the substances remain so low that the structure of the workpiece does not change.

Until now, the methods of production have prevented a breakthrough in miniature chemical plants, which have been limited to use in research labs, say IKTS. That could change: “We can now build ceramic components that fit the application instead of the production process,” says Moritz. ”To date, ceramic microreactors have mostly been milled out of plates. Internal and external sealing have always been a technological challenge for this. And there has been the problem of making connections that fit. Now we can just print them onto the ceramic component during manufacturing in whatever form.” This benefits not only doctors, but also pharmacists and chemists. In most cases, they are processing very expensive or hazardous substances. ”It is more affordable and safer to first work with minimal quantities in a microreactor,” says Moritz.