Technological progress is making its mark in almost every industry, generally succeeding in raising both quality and productivity to new levels. Additive manufacturing processes are among these technologies, which are finding their way into an increasing number of application areas. While such processes, commonly referred to as 3D printing, have been used in the manufacturing industry for some time, they hold particular potential in medical technology, especially since the individuality of the human body requires the highest degree of manufacturing precision. Even though the final potential of additive manufacturing is still up in the air, it is already being used successfully in numerous areas of medical technology.
How does additive manufacturing work?
Although additive manufacturing, i.e., the layered creation of workpieces, has been used for centuries, for example in ceramics processing, it is the digitalization of these processes that defines the essence of additive manufacturing, especially in medical technology. Fundamentally, all manufacturing processes used are based on the use of three-dimensional CAD models, which are either previously created manually in the appropriate modeling software or obtained from existing patient data from imaging procedures.
From the CAD data, the production systems then calculate the necessary geometry and position data, information about the layer thickness, and, if necessary, support structures during the slicing process. Once the data is available, the stored object is produced fully automatically and in open space, with computer-controlled lasers or extruder nozzles ensuring highly precise results that are difficult to achieve manually and are reproducible in large quantities.
Which processes are used in medical technology?
Since medical technology focuses on the development and creation of highly complex and resilient components and prototypes, the range of additive manufacturing processes used is somewhat limited compared to other application areas. The focus is primarily on laser-based processes such as stereolithography (SLA), selective laser sintering (SLS), and selective laser melting (SLM). These three manufacturing processes differ in terms of the materials used and the type of laser used.
While in the case of stereolithography the object to be manufactured is created in a bath of photosensitive liquid plastic and is then cured layer by layer by exposure to the high-power laser, selective laser sintering and selective laser melting are characterized by the layer-by-layer melting of a powdered starting material. http://www.vioproto.de/additive-fertigung-manufacturing The above-mentioned procedures are explained in detail based on their characteristics.
Which materials can be used with additive manufacturing processes?
In addition to plastics, which are primarily used in stereolithography, additive manufacturing in medical technology is primarily characterized by metallic materials that can withstand significant and sustained mechanical stress, especially when used in the body. Examples include biocompatible titanium and various magnesium alloys. Both materials are primarily used in SLS and SLM processes. However, material and process development is far from over, as both the development of ceramic materials and the development of techniques such as electron beam sintering, which also enables the processing of high-strength steels, are promising for medical technology.
Why is additive manufacturing revolutionizing medical technology?
The advantages that additive manufacturing offers for medical technology, and especially for prototype production, are obvious. Computer-aided manufacturing is not only highly precise but also significantly faster than manual production. This makes production via additive manufacturing significantly more cost-effective in the long run, enabling better and more comprehensive medical care, including medical implants and prostheses.
Furthermore, the generative layered construction also allows for the creation of complex hollow chamber structures that are difficult or even impossible to achieve using conventional methods. The individuality of the human organism, which represents the greatest challenge for medical technology, is the greatest advantage of additive manufacturing processes, as prototypes can be produced automatically based on MRI images or CT scans.
How is additive manufacturing currently used?
In medical technology, there are two major areas of application for additive manufacturing processes. On the one hand, there is the production of medical tools, where the honeycomb hollow chamber design allows for significant weight and thus material savings, while simultaneously producing completely enclosed objects that offer no points of attack for pathogens.
Such tools are currently being manufactured for surgical procedures, for example, and are equipped with integrated RFID chips in additional hollow chambers. These chips store, among other things, the information about which staff member last disinfected the instrument. Custom-fit drilling templates or surgical models that depict the initial preoperative situation are already in clinical use and enable efficient planning and execution of operations.
Additive manufacturing enables precisely fitting implants
The second major area of application concerns the production of customized implants that are tailored down to the last detail to a patient's anatomical features. Additive manufacturing processes are currently being successfully used, for example, in the production of precisely fitting titanium joint heads and sockets that are precisely adapted to the patient's body. Furthermore, partial bone implants are already a reality. These not only replace the original bone with a precise fit, but also reduce operating time and potential complications, as no additional surgical field is required for the removal of an autologous bone graft. Other areas of application for additive manufacturing processes:
– Production of dental implants
– Generative manufacturing of custom-fit hearing aids and cochlear implants
– Manufacturing of individual prostheses
– Cost-efficient production of complex surgical instruments in just a few steps
What does the future hold?
The current state of research is particularly interesting with regard to the development of complex implants, some of which are fully bioresorbable. At the Laser Center Hannover, for example, research is being conducted into hybrid implants for the reconstruction of craniofacial defects. These implants are based on a customized lattice structure made of magnesium and titanium, and are designed to promote and facilitate revitalization with tissue cells.
Using processing techniques such as laser micromelting, work is also being done on microimplants that can be integrated into implants, among other things, and used to deliver drugs to the target tissue. In particular, the combination with bioactive components and the production of customized microimplants that can be inserted inside blood vessels, for example, continue to hold significant development potential for the future. This demonstrates that the use of additive processes in medical technology is still in its infancy.