Our Info-Letters

Calcium phosphate ceramics are well established materials for bone regeneration and orthopedic implant coatings. Yet, navigating their regulatory requirements remains a challenge. In particular, the selection of pre-clinical tests is complex and varies depending on the target market of the product.

Our new milling test setup enables us to quantify the wear resistance of side-cutting tools. The test is important, not only for manufacturing technology, but also for analyzing the wear and cutting properties of surgical instruments. It allows the performance of milling tools designs to be compared and optimized.

Our latest electrodynamic test-ing machines enable fatigue tests with calibrated loads starting at 4 N. In combination with the DIC method (Digital Image Correlation), this opens up the world of optical deformation tracking of specific locations, even during dynamic tests.

Positive Material Identification (PMI) determines whether a material or a component has the required chemical composition. The focus is not on the exact chemical composition, but rather on proving that the material is the correct one. The analyses can be carried out either in the laboratory or in the field using a mobile device.

Yttria-stabilized zirconia polycrystal (Y-TZP) is an exceptionally hard and tough ceramic material. Under mechanical stress and in humid environments it tends to transform to a mechanically weak monoclinic phase. To guarantee long-lasting integrity, the monoclinic phase content on the surface of Y-TZP implants must be monitored. RMS Foundation now offers ISO 17025-accredited quantification of the monoclinic phase according to ISO 13356:2015.

Leachable and extractable chemicals may undermine the safety of a wide range of products, particularly in the field of plastics, metals and alloys. The use of such additives cannot always be avoided as they are often responsible for the specific properties needed in a product. 
The RMS Foundation has a wide range of analytical tools at its disposal to determine the chemical nature and content of such leachable and extractable compounds down to the lowest concentration ranges.

Medical products, food and other products are often sealed for air-tight packaging. There are various standardized tests available to verify the quality and leak tightness of the seals or the whole packaging.

Calcium phosphate ceramics are widely used for the repair of bone defects and as coatings for orthopaedic implants. In order to match the growth rate of new bone, the resorption properties of these materials must be carefully controlled. In particular, the resorption rate may be affected by foreign crystalline or amorphous phases or chemical contamination. In vitro testing of the dissolution kinetics as well as the (equilibrium) solubility of calcium phosphates provides an indication of the stability of the material in the human body. Therefore, dissolution testing is required in ASTM F1926 and the determination of the solubility product is recommended in ISO 13779-6.

RMS Foundation has been active in the research of calcium phosphate bioceramics for more than 35 years. During this time, our experts have developed materials with outstanding physical and chemical properties. As a testing, research, and consulting institute, we offer our expertise to partners from academia and industry. Our services include transfer and implementation of specialized manufacturing processes to the clients’ facilities, consulting to improve existing processes, and supply of raw materials and samples for research projects.

Do you know the behaviour of your products under impact loading? How does the individual component, the assembly or the hardened material behave? What is the failure mode after what number of impacts? 
If you want to clarify such ques-tions, RMS with its know-how offers an ideal possibility to measure these properties.

The cleanliness of medical devices (MD) is a critical factor and is addressed in ISO 19227, for example. Due to the manufacturing process, packaging and sterilization, substances hazardous to health may remain on the end product. The same applies to MDs that are reprocessed after use. In both cases, the products go through a validated cleaning process which must also be checked and verified. With the TOC/TIC/TN analyzer, RMS now has the possibility to offer its customers, in addition to existing methods, a further accredited service in the field of cleanliness analysis. The possibility to collectively quantify organic contaminants and proteins via their C and N content, makes this method simple, fast and therefore cost-effective.

Do you know the behavior of your products or individual components under torsion? How does the component, the connection or the material behave under torsion? Is there torsional backlash when the load direction is reversed? If you want to clarify such questions, RMS offers with its torsion testing machine an ideal possibility to measure such characteristics.

Many medical devices consist of several components and are exposed to cyclic loads during their use. This can result in micro-movements between the individual parts, which can produce wear particles. If the medical device is implanted in a patient, particles are released into the body over the period of use.
In order to prove the safety of a product, many medical device manufacturers determine the type, quantity and size of the abrasion particles, which are formed in a simulated mechanical stress situation. Such tests are also increasingly required by the regulatory authorities.

Do you know the cutting proper-ties of your drill bits?
Do you want to compare the wear behavior of different cut-ting edge geometries?
With the test rig from the RMS, such properties can be measured quantitatively. This will help you to qualify your drill bits on the basis of objective measurement data and statistical evaluations.

The quality and safety requirements for medical devices are becoming increasingly stringent. For this reason, the cleanliness of medical devices is being examined more closely. With its many years of experience in analytical chemistry and certification of medical devices, RMS offers its customers the planning, execution, and documentation of cleanliness determination. If possible, the analyses are carried out in our own laboratories, otherwise we rely on competent laboratories, to which we can forward analyses in agreement with the customer.

Calcium phosphate ceramics (CaP) such as β tricalcium phosphate (β-TCP) and hydroxyapatite (HA) are among the best-known synthetic materials used surgically for filling of large bone defects. In order to ensure patient safety and provide optimum support for bone healing, the products must meet high requirements in terms of chemical purity, phase composition, microstructure and mechanical properties.  Synthetic CaP bone graft substitutes are therefore tested for conformity with ISO 13175-3 to get market approval in Europe.

In recent years, additive manufacturing (AM) has developed into a promising manufacturing technology with revolutionary possibilities such as «complexity for free». In contrast, the physical properties of these inhomogeneous or layered components are often neither known nor assessable. This entails new risks and challenges with regard to the quality and reliability of such products, especially for applications in medical technology. The RMS Foundation (RMS) has been pursuing this technology for years in its own projects with a focus on product safety. As a result, a number of AM-specific analyses have been established in the RMS, from investigations of the raw material to the component, supporting the step from the laboratory to series production.

When testing technical cleanliness, function-relevant components are specifically examined for particle contamination resulting from the manufacturing process. Even the smallest particles can cause nozzles or filters to clog, valves to jam or bearings to block. On printed circuit boards, a chip can unintentionally connect conductor paths. Components and systems can fail as a consequence.

Inorganic chemical analysis plays an important role in guaranteeing the safety and performance of countless materials and products. In particular, medical devices in contact with the human body must comply with strict maximum limits of potentially harmful elements such as heavy metals. ICP-MS is an extremely sensitive technique that allows simultaneous quantification of 70 elements down to trace levels in the µg/L or sub-µg/L range, and can therefore handle a large variety of analytical challenges.

This test method is used to determine the mechanical seal strength when separating the entire cover (lid / membrane) from a rigid or semi-rigid container (blister) according to ASTM F2824 or ASTM F88.
The continuous forces required to separate the lid will be evaluated as well as the maximum seal strength and the work. Furthermore, the mean value can be determined over the entire graph or e.g. from the «valley to valley» area. The lid is separated at a constant angle of 45° over the entire test period. This is implemented with an additional horizontal movement of the blister.

By means of CGHE analysis, carbon, sulfur, hydrogen, nitrogen, oxygen and argon can be quantitatively determined in metallic and non-metallic materials. The samples are melted under a gas atmosphere suitable for each element (carrier gas). For example, helium is used as a carrier gas for O, N and Ar analysis. For the H measurement, however, nitrogen is used as the carrier gas. In the C and S determination, carbon burns with oxygen to CO₂ and sulfur to SO₂. The analysis is then carried out by means of selective infrared detection (O, C, S), via the change in the thermal conductivity (H, N) or by means of a mass spectrometer (Ar).

The crystal structure of ceramics, metals, and polymers drastically affects their physical, chemical, and biological properties. Even materials with the same chemical composition but different structures can be substantially different in many aspects. A common example of such polymorphs is diamond and graphite. Both are made of carbon, but while diamond is exceptionally hard, transparent, and precious, graphite is soft, black, and of no particular value. Similar examples exist in the fields of biomaterials (e.g. calcium phosphate bone void fillers, yttrium-stabilized zirconia dental implants) and metals (e.g. allotropes of steel), in which polymorphs with different physico-chemical or biological properties may occur.

Failure analysis is used to determine the cause of a failure and to prevent future failures. The knowledge gained can be used for the overall risk assessment as part of the technical documentation. In addition to clarifying the cause and identifying risks and hazards, failure analysis thus provides useful information for designers, product developers and users (surgeons). In the area of post-market surveillance, failure analysis provides continuous feedback on implants on the market and can help to document high quality and high product standards. 

Infrared radiation lies in an energy range that is absorbed by molecular bonds through vibrational excitation. The absorption bands and spectra are characteristic of the examined organic material, providing a molecular fingerprint. The RMS Foundation has an FTIR microscope for the characterization and identification of organic materials. It enables the study of small particles and fibers (down to 30 microns), and their identification based on a spectral library with more than 25,000 reference spectra.

The surface structure and its roughness are decisive for many applications. Thus a quick and accurate measurement of these properties is essential.

In component or material testing, displacement and acceleration sensors are often employed to gain detailed information on specific points. With the aid of a dynamic optical measurement system, such data can be obtained in a contactless manner with relative ease.

Previously, separate circuit boards were installed in electronic devices. Today, the trend is in the direction of the three-dimensional, injection molded interconnect devices (MID). These devices not only replace the conventional circuit boards, but at the same time provide many additional features. For developers and manufacturers of MIDs and electronic components, the RMS Foundation offers a number of useful laboratory services.

Particles play an important role in many applications. Therefore, in-formation about their size, number and shape are of major concern. For example, wear particles of artificial joints are considered the main cause of bone resorption and prosthesis loosening. Similarly, strong ceramics rely on a good control of the particle size distribution of the raw material. Laser diffraction has become the leading technique in particle analysis during the last years. Benefits are short analysis times, good reproducibility and ease of calibration.

About ten years ago, contaminated hip shells required several hundred revision surgeries and the products had to be recalled from the market. This event was an alarm call for the medical device industry. Companies realized that neither the best biomaterial nor the best engineering solution are successful if the process chain and the cleaning of the implants were not very well-controlled and understood.

Materials that deform plastically at low loading rate and hereby absorb much deformation energy may become brittle at high loading rate, especially under impact or notched conditions. Products and materials with low impact toughness will break brittle and after low plastic deformation. The Charpy notched impact test is an ideal tool to assess the effect of loading under striking conditions on the failure mode of materials.

The RMS Foundation was commissioned to analyze forceps, which discoloured to dark grey in the daily use during cleaning and conditioning with the thermodesinfector. 
The goal of the study was to figure out the reason of the colour change and how it can be avoided  in the future.

A surface can be quickly ­ch­aracterised by measuring the contact angle: is it hydrophilic or hydrophobic? Is a sample contaminated? Did a coating process work?

A prior newsletter dealt with both function and use of the scanning electron microscopy. Now this issue provides further examples for the successful use of the scanning electron microscope (SEM) in material research and testing.

In the material research and testing, the SEM is a multipurpose and indispensable instrument for the analysis and depiction of surfaces and structures. The field of application of the electron microscope begins where the classic light microscope reaches the limits of the resolution or of the depth of focus. In the RMS Foundation a modern SEM with an EDX analysis unit (Energy Dispersive spectroscopy by X-rays) is available for customer mandates. It is specifically used for material as well as surface examinations.

Would you like to reduce the failure risk of your products, components or parts? – Do you need materials that have to comply with specific mechanical requirements? – Would you like to examine whether your raw material meets your specifications? 
If your answer to such questions is «Yes», a mechanical test with a load that is in step with actual practice is required. Static and quasi-static investigations are optimally suited to test and evaluate raw materials and/or the structural characteristics of components even at a very early stage of development and of production.

What are those stains on the product? How clean is the surface? Why does the coating come off again and again? Was the plasma treatment effective? 
X-ray photoelectron spectroscopy helps to answer such questions. This analytical method allows for the determination of the chemical composition in the top 5-10 nm of the surface.

The components, component parts and products are developed and produced for very specific uses. It is frequently the fatigue strength that is decisive for the operational reliability, on which the design, the choice of materials, but also the surface design have quite a substantial influence. The static strength can be assessed by simpler means. A confirmation of the operating safety by assessing the fatigue strength is much more elaborate and generally calls for a dynamic functional test.