MZT - Mikromedizintechnik
Injury to the anterior and posterior cruciate ligaments is not an uncommon occurrence. A rapid movement can already cause such an injury. Reconstruction of the anterior and posterior cruciate ligaments (ACL/PCL) in the knee joint is a complex orthopedic challenge. In this context, the development of a graft preparation system is gaining importance. Such a system will help surgeons prepare grafts accurately and efficiently to optimize reconstruction processes. This can increase the accuracy of graft placement, reduce surgical times, and decrease recovery time and postoperative risk for patients.
This paper focuses on the development of a graft preparation system for ACL/PCL reconstruction in collaboration with Getsch+Hiller Medizintechnik. The challenges and requirements in developing such a system were analyzed to ensure functionality and effectiveness. Existing approaches and technologies were examined to identify potential improvements and innovations. Development included extensive research on ACL/PCL reconstruction using grafts, including various surgical techniques. A detailed analysis of the graft preparation process was performed to identify critical issues. The design of the graft preparation system is based on research data and is performed using CAD. The needs of the target group, customer requirements and findings from research were considered.
In the course of researching a bellows to encapsulation the mechanical unit of a moving active implant, two photopolymer resins were calibrated for further investigation as part of this research. This has been done using a masked stereolithography (MSLA) printer, cleaning steps followed by curing. The resins were one biocompatible and the other with special flexibility. The evaluation of the printing was carried out using a validation matrix for SLA printing processes. The time required for the process steps had been observed as well. Both resins were calibrated with respect to their exposure time and the process chain was evaluated. The results are meaningful, but additional factors had been identified that need to be considered too.
In this work, the comparability of the cooling effect of two Peltier elements from different manufacturers is investigated for cooling the reagent module of a chemiluminescence analyzer. The temperature inside the reagent module is measured and evaluated at several positions. In this study, two different types of verification tests are performed under extreme climatic conditions. On the one hand, in a specific functional “cold start test”, the temperature in the reagent module is measured and evaluated to determine whether the measured temperatures are within the specified temperature range after the specified time. In addition, the performance of the Peltier elements is also evaluated. On the other hand, as an unspecific regression stress test, a “smoke test” is performed that is mainly designed to allow identifying unpredictable events. While processing a long and
complex work list, any deviant system behavior can be detected. Again, the temperature inside the reagent module should not exceed the specified temperature range.
Parylene-C is a multifunctional polymer coating in the coating industry. In medical technology, it is approved for implants due to its biocompatibility. For example, it is used as a coating for electronic components and parts. The problem is that Parylene-C alone is too permeable to body water and the ions that are dissolved in it. Application as a coating material for long-term implants is therefore not possible. The infiltrating water not only corrodes the electronic components, but also reduces the adhesion between the Parylene-C and the coated surface. Therefore, layer systems of metal oxides and polymers are used for encapsulation. The aim of this work is to find out how different layer systems behave in relation to their water vapour transmission. Thicker systems should allow less water vapour to pass through than thinner ones. The task is to find this out using the test method for water vapour transmission barriers and to determine the water vapour transmission rate. It has been proven that in some cases the thicker layers performed worse than the thinner layer systems by a factor of ten. It has been shown that there is a relationship between the base substrate thickness, the thickness of the layer system and their flexibility.
Parylene-C is used for various biomedical devices because of its high conformity and biocompatibility. However, delamination could occur because of low adhesion between Parylene-C and other materials. For this experiment 4-inch Si-wafers are used. Parylene is deposited by chemical vapour deposition (CVD). Silane A-174 as adhesion promoter is added between Parylene-Parylene layers. The samples are soaked at different duration 1 h, 24 h and 120 h in PBS solution at 37 °C. A peel test is further performed to investigate the adhesion properties of the samples.
This work gives the theoretical background which is needed to understand what self-assembling monolayers are, how they work, how and for what they can be used. A closer look is taken on the possibility to create an area selective atomic layer deposition process. In a practical experiment the foundation for this process is laid. Therefor a silicon wafer is coated with gold using a evaporation process. The gold samples are exposed to the SAMs solution to grow them. Contact angle measurements as well as Fourier transform Infrared spectroscopy are used to check the existence of SAMs on the gold samples. Also there is investigated if different exposure times make any differences.
Investigation on adhesion strength of Parylene-C coatings with different adhesion promotion methods
(2021)
Delamination of encapsulation materials (here the polymer Parylene-C) is one of the biggest failure mechanisms for active medical implants. This problem is addressed by the application of different pre-treatment and adhesion promotion methods. The methods applied in this research are oxygen and Silane A-174 solution pre-treatment and Silane A-174, titanium oxide and Trimethylsilane as adhesion promoters. The adhesion forces of these methods are quantified after different soaking times in phosphate buffered saline (PBS) solution to mimic environment of the human body.
ALD can be used in medical technology to produce thin and stable protective coatings. For example, such coatings can be used as tarnish and oxidation protection for silver electrodes used in high-frequency surgery. For the investigation of the pretreatment method, platelets of sterling silver were used instead of silver electrodes. Three methods were used to pretreat the silver substrates. The first pretreatment method is cleaning with acetone and isopropanol. In the other two, the samples are additionally cleaned with a phosphoric acid etching mixture or citric acid. The pretreated substrates were coated using the atomic layer deposition method. 45 nm of aluminum oxide was deposited on the silver samples, followed by another 45 nm of titanium oxide. Subsequently, the samples were autoclaved in order to check the clinical routine and the reusability. The results show a significantly improved adhesion in contrast to samples that were not cleaned. The layer no longer flakes off the silver substrate. Nevertheless, small blisters appear on the protective layer after autoclaving. These indicate that the layer is weakened by the stress.
Optogenetics and optogenetic systems cover a wide range of applications in the research of neurological pathways. In this overview, relevant aspects regarding the development of optogenetic systems should be shown. These are the optogenetic systems – opsins and optical switches – as well as optoprobes, materials, application areas and limitations of these applications. Additionally, a short outlook should be given. No detailed analysis for specific optogenetic systems or their partial aspects were carried out.
In the present work, polyetheretherketone (PEEK) was pretreated with oxygen plasma to investigate the influence on the contact angle and surface energy. For this purpose, PEEK samples were fabricated over several manufacturing steps, which were used as substrates for later investigations. A series of measurements was performed at a power of 300 W for different treatment durations and the contact angle of H2O on the PEEK surface was determined. The results show that plasma pretreatment significantly affects the surface modification of PEEK disks. The best hydrophilic properties of the PEEK surfaces were measured at a treatment time of 540 s and a power of 300 W. A much longer treatment time caused the correlated values of contact angle and surface energy to increase and in this case an excessive treatment time did not contribute to a further increase in hydrophilicity.