Refine
Document type
- Contribution to a Periodical (3)
- Conference Proceeding (1)
- Report (1)
Is part of the Bibliography
- No (5) (remove)
Course of studies
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.
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.
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.