Amorphous Alloys in Medical Technology

Preferred materials for personalized implants, orthopedic and medical devices are facing a multitude of high requirements at the same time. Besides biocompatibility standards, manufacturability and surface functionality, especially the adaption of complex individual geometries are current challenges that create the bottleneck between a material solution approach and the application reference. The promising approach of using amorphous metals in this context has already been shown to be viable in practical studies and implementations. The potential to overcome previous challenges in design, functionality, and biocompatibility for biomedical applications from amorphous alloys have already been confirmed in in-vivo results. The demanding applications in medical technology demonstrate the advantageous fields of action of amorphous alloys, which unfold their potential in these challenges and open up new possibilities for providing better care to patients in the future.

The advantage of near-net-shape manufacturing technologies combined with the exceptional properties of amorphous metals is able to overcome the acute dilemma between load and movement in the bone healing process. Due to their atomic structure, amorphous metals exhibit high elasticity combined with high strength. Biomechanical forces are thus cushioned and stabilized. With the help of amorphous 3D printing and amorphous injection molding, Heraeus AMLOY is able to realize individualized implants or complex geometries in the field of orthopedic surgery and traumatology within narrow tolerances. The same applies, of course, to flexible and at the same time stable standard implants. Porous surface structures that facilitate the ingrowth of bone structures can be produced, as can smooth surfaces that guide this growth in a targeted and functional manner. While conventional materials require many post-processing steps for this, the amorphous alloy AMLOY-ZR01 realizes surface qualities in the range of 1.0 μm without extensive post-processing. For even higher requirements, even values in the range of Ra 0.05 μm can be produced by glass bead irradiation. The powder particles are then cleaned by ultrasonic cleaning. Especially in complex orthopedic fractures, the potential for Heraeus AMLOY alloys is enormous. The improvement of the healing process, individualization and component optimization, as well as elasticity and strength under permanent load, are all achieved here in comparison to conventional approaches.

Common protective medical devices for injured cranial and craniomaxillofacial areas range from plate types to mesh-like constructions. The focus is not only on correcting cranial deformities, but also on restoring the aesthetics of the skull and increasingly on patient-specific adjustments. While conventional titanium alloys or the partial use of PEEK material offer satisfactory biocompatibility properties, the combination of high strength and high elasticity has not yet been achieved. 

This is precisely where Heraeus AMLOY comes in with the use of amorphous metals. Amorphous metals are characterized by the combination of high strength for stabilization and simultaneously high elasticity for efficient flexibility, which is described above as necessary. They are also highly adaptable via 3D printing or amorphous injection molding. Thus, simplified handling of implants can be rounded off with patient-specific adaptation and high mechanical property qualities of amorphous metals.

In particular, the use of mesh designs in combination with amorphous metals is an exciting starting point. Open structures can be designed to be thinner, wider and lighter and, thanks to the amorphous metallic material structure, allow greater flexibility combined with higher stability than conventional materials. The amorphous material's good elasticity could also prevent the risk of fractures in surgery.

Despite all the progress made in spinal surgery through constructive adaptions and outstanding successes in minimally invasive surgery, another field of optimization remains unrecognized. The improvement of the entire value chain, from the production of medical devices to the application on the patient, using adequate functional materials.

In particular, the field of amorphous metals represents a great potential in this context. While in the past, limits in terms of non-toxic purity and biocompatibility, as well as replicability in high quality, steadily prevailed the use of amorphous metals in medical technology, Heraeus AMLOY is now able to turn these levers in the desired direction.

With near-net shape manufacturing technologies like amorphous injection molding and amorphous 3D printing, we are able to produce state of the art components with certified biocompatibility and enhanced biomechanical properties that solve current challenges. In the critical area of the spine, reliable material properties are necessary. With an elasticity of up to 2% at a strength of up to 2,000 MPa, components made of amorphous metals support the spine in stability and flexibility at the same time. The Young's modulus of 85 GPa is even closer to the cortical bone than conventionally used alloys. This could finally solve problems of subsidence or stress-shielding with an also extended shock absorbing behavior. At the same time, the properties of the amorphous metals offer the possibility of dimensioning the components more ideally for spinal applications. Thus, Heraeus AMLOY is even able to produce the most complex structures and porosities by using 3D-printing to support a long-lasting fusion and product life cycle.

Especially in the field of dental implants, functional surfaces, patient-specific designs and the least invasive therapy possible are of importance. Many possibilities are used to sustainably improve the healing process and the implementation efficiency of the interventions. The options vary from component coating by using bone-like substances to the design of components with porous structures. In addition, the potential in this area also lies in the selection of materials that can address previously unsolved problems, particularly by using functional materials. 

In this context, amorphous metals show their beneficial properties and represent an improvement over previous solutions in terms of their mechanical properties. Considerations of the forces acting during a jaw movement, for example, illustrates the biomechanical stress to which implants are subjected during interacting continuous loading. Due to the necessary construction details, the design of dental applications is reaching its limits.

With the near-net-shape manufacturing technologies of amorphous 3D- printing and amorphous injection molding, as well as an intensive expertise in materials technology, Heraeus AMLOY is able to serve as a contract manufacturer for high-quality and efficiently designed amorphous components. Components made of amorphous metals exceed conventional materials in many medical applications due to their good durability, high elasticity and high strength. In the dental field, not only can the aforementioned design optimizations be extended and withstand the high biomechanical stresses, but also entire healing processes can be shortened and life cycles of implants can be extended due to less invasiveness and possibly even less maintenance.

Stability

• Under both static and fatigue load
• Good biomechanical performance

Durability

• Wear resistance
• Miniaturization by higher strength

Biocompatibility

• Bone-implant interaction
• High corrosion resistance

Whether large and open housing structures of medical instruments or functional minimally invasive tool components, amorphous metals have a variety of advantageous properties for the use in the field of medical technology tools. Heraeus AMLOY significantly realizes these advantages with efficient manufacturing technologies. Reproducible and high-quality component production within tight tolerances (± 10µm) is realized in the amorphous injection molding process due to our material-specific know-how.

Insert tools in minimally invasive surgery require high dimensional accuracy in production and, at the same time, high load-bearing capacity in use. Whether forceps, grippers or special hooks, amorphous metals can be manufactured in many dimensions and close tolerances in a scalable manner for long-lasting applications. Due to their very good biocompatibility combined with high strength, they have proven to be very abrasion resistant. In addition, very sharp edges can be realized in the form of scalpels and cutting tools due to the absence of grain and phase boundaries. These ones also surpass conventional materials in terms of wear resistance and cutting ability.

While functionality is based partly on mechanical properties, the surface quality of potential amorphous medical instruments is at least equally important. While conventional materials require many post-processing steps for this, amorphous alloys in particular have surface qualities in the range of 1.0 μm without post-processing. Even haptic properties can be cited, as amorphous metals signal a very high-quality surface due to their low thermal conductivity.

Tight Tolerances

• Complex shapes
• Reproducible manufacturing

Surface Quality

• High quality
• Functional surface

Wear resistance

• Durability
• Biocompatibility