VF 73Manufacture and application of custom designed diamond knives realized by an innovative process based on semiconductor fabrication techniques
C. W. Spraul1, A. J. Knittel1, E. Kohn3, P. Gluche2, A. Flöter2, G. K. Lang1
Purpose: The application of diamond knives has dramatically increased the cutting performance in ophthalmic surgery including cutting tissue for both light microscopy and transmission electron microscopy in ophthalmic pathology. However, the lateral geometry of the blade, its thickness and the sharpness of the cutting edge are limited by the abrasive diamond polishing process, e.g. the crystalline morphology of the bulk material and the used grinding powder. Here, a new generation of diamond blades is presented, enabling free choice of the blade shape, the thickness and showing excellent sharpness as a result of a new polishing process.
Methods: The new fabrication method is based on a high quality CVD diamond film of some tens of microns in thickness, deposited on a silicon wafer as known from microchip-technology. The mechanical properties of this synthetic diamond film are almost equal to those of natural diamond and the surface of this film is mirror-like after deposition without the need for post-polishing. The shape of the blade can be laterally defined concerning the surgeons proposal and is transferred into the diamond film by a plasma polishing process adopted from Microsystems technology.
Results: The new production method results in highly reproducible, laterally free-formed diamond blades. Concave formed blades cutting at the inner as well as the outer edges and round forms can now be realized without the restrictions given by process-induced facets. The force-free fabrication method even allows the realization of miniaturized blades (e.g. width < 0.125mm, thickness < 50 µm) far beyond the possibilities of conventional diamond blade production. The plasma polishing by gas atoms leads to an extreme sharpness with the cutting edge radius in the range of approx. 20nm, investigated by scanning electron microscopy.
Conclusion: Diamond blades fabricated using an innovative new production process will be presented. The new process for the first time offers surgeons the possibility to design blades with a geometry close to their personal needs. Furthermore, the potential of facet-free ergonomically shaped diamond blades may stimulate further improvements towards novel surgical techniques.
1Department of Ophthalmology, University Eye Hospital and Clinic, University of Ulm, Prittwitzstrasse: 43, D-89075 Ulm; 2GFD mbH, Wilhelm-Runge-Str. 11, D-89081 Ulm; 3Dept. of electron devices and circuits, University of Ulm, Albert-Einstein-Allee, D-89069 Ulm